We manufacture a pump in China. The reason we have it done in China is to provide an actual profit margin. We started manufacturing it in the US, but it reached the point where it just cost too much, it was either fold up the company or outsource to China.
We opted for outsourcing the pumps to China.
We’ve been having the strangest problem concerning the lip seal we use to seal our pump motor shaft. It is a standard 1/8 inch cross section x ¼ inch ID x ½ inch OD lip seal. After we started manufacturing the pumps in china we began having substantially more warranty returns due to leaky pumps.
It took a long time, but we finally realized that occasionally the seal would spin inside the plastic gland it is contained within. It turned out that for 10 years we had been using the wrong cross-section type of seal, which was symmetrical. Now the factory is telling us we shouldn’t use that type of seal for a rotary shaft application. It would have been nice if they had mentioned it 10 years ago when they helped us choose a seal.
And it worked so well for 10 years! Thinking back on it, we now know why we had some mysterious leaks even back then. There were a whole host of changes we made when we switched to the Chinese manufacturing, but we still used the same motor shaft sealing technique and seal.
To solve the spinning problem the Chinese manufacturer had some custom seals molded, but when he did the life-testing, the seals were only lasting from a couple of minutes to an hour or so. Wee need a 500 hour life or better.
We spent weeks trying to figure out why the seals only seemed to last for a few minutes to a few hours when the Chinese manufacturer did life testing on them. Our life testing of the US seals we had been using was getting life expectancies of about 500 hours, unless they spun of course.
We could not figure out why the Chinese tests were so poor… let’s say catastrophic, Same motor and pump, same stainless steel shaft, same plastic pump housing, same water pressure and temperature. We decided it had to be the material the Chinese were using.
We found a compounder here in the US who would custom make us the rubber material, Nitrile, with the properties we needed for our pump. The minimum order cost us about $1,000 but we got enough material to make about 80,000 pumps. The seals are pretty small after all.
It took about a month to get the compounder to furnish us the batch of nitrile and we shipped a small portion off to China for them to mold into lip seals.
Again the Chinese life testing resulted in seals only lasting minutes. We investigated the curing times and molding method the Chinese factory was using and tried changing those parameters. Same result.
I was getting quite frustrated. The Chinese were blaming “abrasion” for the problem. I told them to send me some samples of the new seal including one of the “failed” seals. When the seals arrived and I found the “failed” seal I was a bit puzzled. I could not tell the difference between the new seals and the failed seal. It looked brand new.
I installed the failed seal in a new pump and began life testing the pump. After about 200 hours of running I took the pump apart and checked the seal. It showed significant wear as would be expected, but inner lip still had more than half the original thickness. There were no leaks.
To be continued…
Thursday, December 31, 2009
Wednesday, December 30, 2009
Tankless Waterheaters – Comparison with Tank Type Water Heaters
Tankless waterheaters can provide you with reduced energy usage and a limitless supply of hot water. There are a few significant differences in the way tankless water heaters work and how standard storage water heaters work.
A gas water heater may need a new thermocouple because the pilot light won’t stay lit, or the high limit switch may need replacement in an electric water heater, other than that and similar minor problems they are pretty darned reliable appliances. You set the temperature dial to warm hot or hottest and forget about it (or the upper thermostat on electric units).
With tankless waterheaters there are some important differences you should be aware of. Tankless units have both a minimum flow rate and a maximum flow rate to be able to maintain a constant outlet temperature. If the water flows too slowly through the heater, the heat exchanger can overheat and become damaged.
Tankless water heaters use a flow sensor to turn on the water heater only if the minimum flow rate is reached. Tankless heaters require ½ to ¾ gallons of water per minute to initiate operation depending on the brand and model. This means you can’t use “just a trickle” of hot water, you need to run at least a half to three quarter gallons per minute to keep the waterheater operating.
Since you will need to mix hot and cold water at the fixture to get a usable water temperature from the faucet, and you must maintain the hot water part to at least ½ gallon per minute or ¾ gallons per minute for larger models, then you could end up needing to use at least a gallon per minute for the right temperature water.
Tankless water heaters also have a maximum flow rate for which they can heat water to the temperature that has been set for the output. Higher flow rates will cause the outlet water temperature to drop.
Some tankless models require periodic maintenance like de-scaling the heat exchanger in hard water areas. Scale buildup from hard water can be a serious problem. The owner’s manual will describe how to clean the scale out if it is needed.
The installation of a tankless waterheater should not be done by someone not trained in installing the brand that is purchased. Improper installation can lead to things like carbon monoxide poisoning, a fire hazard, or unstable water heater operation.
Tankless water heaters take time to heat water to full temperature, so they take a little longer to deliver hot water to the fixtures, typically 10 to 20 seconds longer. That means more water being run down the drain while you wait for hot water.
If you have a need for large volumes of hot water tankless waterheaters are the way to go. Just make sure you size it correctly and have it installed correctly. And if applicable add a hot water demand system as well.
Derived from my article: Tankless Waterheaters
A gas water heater may need a new thermocouple because the pilot light won’t stay lit, or the high limit switch may need replacement in an electric water heater, other than that and similar minor problems they are pretty darned reliable appliances. You set the temperature dial to warm hot or hottest and forget about it (or the upper thermostat on electric units).
With tankless waterheaters there are some important differences you should be aware of. Tankless units have both a minimum flow rate and a maximum flow rate to be able to maintain a constant outlet temperature. If the water flows too slowly through the heater, the heat exchanger can overheat and become damaged.
Tankless water heaters use a flow sensor to turn on the water heater only if the minimum flow rate is reached. Tankless heaters require ½ to ¾ gallons of water per minute to initiate operation depending on the brand and model. This means you can’t use “just a trickle” of hot water, you need to run at least a half to three quarter gallons per minute to keep the waterheater operating.
Since you will need to mix hot and cold water at the fixture to get a usable water temperature from the faucet, and you must maintain the hot water part to at least ½ gallon per minute or ¾ gallons per minute for larger models, then you could end up needing to use at least a gallon per minute for the right temperature water.
Tankless water heaters also have a maximum flow rate for which they can heat water to the temperature that has been set for the output. Higher flow rates will cause the outlet water temperature to drop.
Some tankless models require periodic maintenance like de-scaling the heat exchanger in hard water areas. Scale buildup from hard water can be a serious problem. The owner’s manual will describe how to clean the scale out if it is needed.
The installation of a tankless waterheater should not be done by someone not trained in installing the brand that is purchased. Improper installation can lead to things like carbon monoxide poisoning, a fire hazard, or unstable water heater operation.
Tankless water heaters take time to heat water to full temperature, so they take a little longer to deliver hot water to the fixtures, typically 10 to 20 seconds longer. That means more water being run down the drain while you wait for hot water.
If you have a need for large volumes of hot water tankless waterheaters are the way to go. Just make sure you size it correctly and have it installed correctly. And if applicable add a hot water demand system as well.
Derived from my article: Tankless Waterheaters
Monday, December 28, 2009
Getting a New Patent - A New Hot Water Demand System Patent – In Real Time.
We recently filed a provisional patent application for our new hot water demand system. A year prior to that we had done what our patent attorney called a “document dump”. As I understand it, that gave us a year’s worth of protections in so far as establishing a date of invention. Once the year expired we decided to pursue a provisional patent.
Provisional Patent
A provisional patent allows you to establish a filing date for your patent, but you can still modify the patent later. However, making later modifications does not extend the protection period… which lasts 20 years.
We filed the new patent application a couple of weeks ago. I just received a letter from our patent attorney.
The letter informs us that our patent has been filed and the USPTO has assigned us a U.S. patent application with our application number and further tells us our official filing date is November 18, 2009.
She also enclosed a copy of a “Notice To File Missing Parts of Application” received from the USPTO. She enclosed a copy of the missing document, the “inventor’s declaration, which she asked me to sign and return. It has to be received by the patent office on or before Feb. 4th.
Another interesting item in the letter is this quote:
“We want to remind you that there is a strict and continuing duty to disclose to the USPTO prior art and other information that is material to the patentability of your invention. There is no obligation to perform a prior art search, but if you already know or become aware of any material information while the application is pending, it must be submitted to the USPTO. We will file an Information Disclosure Statement with the USPTO for the search that was done prior to filing of this application.
If you or anyone associated with the prosecution of this application knows or becomes aware of any information that may be material to the patentability of the invention, please contact me so that I may arrange to have the information submitted to the USPTO. If I do not hear from you, I will assume that there is no additional information to submit at this time. “
So in other words, if I surf the internet tomorrow, and I stumble across something that might impact my patent application, I am obligated to inform the patent office.
The letter also states that the USPTO typically publishes an application at about 18 months from the original priority date.
One more quote that could interest some viewers:
“The American Inventors Protection Act of 1999 makes available to patent applicants extensions of the patent term where the USPTO causes delays during examination. The USPTO defines the types of delays giving rise to such extensions of time. However, any potential term extensions caused by USPTO delay are offset or reduced by any delays caused by an applicants' "failure to engage in reasonable efforts to conclude prosecution." Consequently, filing any papers (Information Disclosure Statements, Responses to USPTO Office Actions, etc.) is best done promptly
The next step, if my memory serves me, is that we will receive something from the patent examiner telling disallowing some of or all of our claims. I’ve never had a patent application that was just simply accepted by the patent examiner. It’s like they have to put up some kind of objection. So I expect that to happen this time as well.
We will argue and usually we will loose a claim or two but keep most of the claims intact or only slightly modified. At least that is my hope.
When I get a reply from the patent office or something from my patent attorney I will be publishing it. Patent reporting in real time... still a snails pace though.
Provisional Patent
A provisional patent allows you to establish a filing date for your patent, but you can still modify the patent later. However, making later modifications does not extend the protection period… which lasts 20 years.
We filed the new patent application a couple of weeks ago. I just received a letter from our patent attorney.
The letter informs us that our patent has been filed and the USPTO has assigned us a U.S. patent application with our application number and further tells us our official filing date is November 18, 2009.
She also enclosed a copy of a “Notice To File Missing Parts of Application” received from the USPTO. She enclosed a copy of the missing document, the “inventor’s declaration, which she asked me to sign and return. It has to be received by the patent office on or before Feb. 4th.
Another interesting item in the letter is this quote:
“We want to remind you that there is a strict and continuing duty to disclose to the USPTO prior art and other information that is material to the patentability of your invention. There is no obligation to perform a prior art search, but if you already know or become aware of any material information while the application is pending, it must be submitted to the USPTO. We will file an Information Disclosure Statement with the USPTO for the search that was done prior to filing of this application.
If you or anyone associated with the prosecution of this application knows or becomes aware of any information that may be material to the patentability of the invention, please contact me so that I may arrange to have the information submitted to the USPTO. If I do not hear from you, I will assume that there is no additional information to submit at this time. “
So in other words, if I surf the internet tomorrow, and I stumble across something that might impact my patent application, I am obligated to inform the patent office.
The letter also states that the USPTO typically publishes an application at about 18 months from the original priority date.
One more quote that could interest some viewers:
“The American Inventors Protection Act of 1999 makes available to patent applicants extensions of the patent term where the USPTO causes delays during examination. The USPTO defines the types of delays giving rise to such extensions of time. However, any potential term extensions caused by USPTO delay are offset or reduced by any delays caused by an applicants' "failure to engage in reasonable efforts to conclude prosecution." Consequently, filing any papers (Information Disclosure Statements, Responses to USPTO Office Actions, etc.) is best done promptly
The next step, if my memory serves me, is that we will receive something from the patent examiner telling disallowing some of or all of our claims. I’ve never had a patent application that was just simply accepted by the patent examiner. It’s like they have to put up some kind of objection. So I expect that to happen this time as well.
We will argue and usually we will loose a claim or two but keep most of the claims intact or only slightly modified. At least that is my hope.
When I get a reply from the patent office or something from my patent attorney I will be publishing it. Patent reporting in real time... still a snails pace though.
Friday, December 18, 2009
Inventions and Inventors – More Asparagus Harvester Problems
Inventions and Inventors – More Asparagus Harvester Problems
Continuing my asparagus harvester invention story…
One of the significant problems we had while trying to develop our prototype asparagus harvester was gaining access to asparagus fields for testing.
There is really no substitute for an asparagus field to test our prototypes on. We’ve devised a number of substitutes over the years, but all suffer from problems. We at times have used blocks of clay with all sorts of stuff stuck into the clay to substitute for spears… plastic tubing, sticks, rubber hose, tulles, and even asparagus spears from the grocery store. We rigged up conveyor belts under the machine with rubber studs sticking up. We even dragged it out to my farm and put tulles into the ground to simulate spears.
But in the end, is just extremely difficult to simulate simultaneously the delicate nature of the spears, the clumping and randomness of the spears, the leaning, the loads presented to the blades by the soil consistency, penetrability of the soil, the ability of blades to cut through spears, variations in bed height etc.
So for about six to eight weeks a year we have the opportunity to run the prototype asparagus harvester on a real asparagus field… if we could find one. It seems that asparagus growers have a couple of problems with testing machines on their fields. First, they earn their money from the asparagus crop, so if your machine doesn’t work well the farmer looses money, and second, it used to upset the crews that picked the asparagus.
There were a few years that worked out, when we would find a farmer that would allow us to cut a couple of rows on the edge of his field. One year a farmer told us we could have an acre well in advance of the season. One week after we got the harvester into his field he changed his mind and tossed us out. Not much testing done that year.
Another time the president of the asparagus growers association told us he would provide us with several acres the next season. When the season arrived he kept putting us off and finally told us he couldn’t find us any acreage. Great.
Part of the problem was that the asparagus growers did not really want to see mechanization come to the asparagus industry. I remember one grower who told me that he hoped that it would be a very expensive machine. The growers were making great money and were afraid mechanization would attract more growers and the increase volume would lower prices.
Now days it’s different. The much lower production costs of our foreign competitors has nearly wiped out the asparagus industry, and if mechanization doesn’t come along soon there will be nothing left. We will get all of our asparagus from Peru and Mexico.
After we hooked up with Washington State University things were different. The University paid farmers for the seasons crop, and any crop we harvested we turned over to the farmer every day anyway. The grower made out like a bandit.
The farmers are also much more interested in mechanical harvesting. The need to find a way to compete with the cheap imports and mechanization is really their only hope. So now they are rooting for us… and if we pay them enough they will let us experiment with our selective mechanical asparagus harvester on their farm.
To be continued…
Continuing my asparagus harvester invention story…
One of the significant problems we had while trying to develop our prototype asparagus harvester was gaining access to asparagus fields for testing.
There is really no substitute for an asparagus field to test our prototypes on. We’ve devised a number of substitutes over the years, but all suffer from problems. We at times have used blocks of clay with all sorts of stuff stuck into the clay to substitute for spears… plastic tubing, sticks, rubber hose, tulles, and even asparagus spears from the grocery store. We rigged up conveyor belts under the machine with rubber studs sticking up. We even dragged it out to my farm and put tulles into the ground to simulate spears.
But in the end, is just extremely difficult to simulate simultaneously the delicate nature of the spears, the clumping and randomness of the spears, the leaning, the loads presented to the blades by the soil consistency, penetrability of the soil, the ability of blades to cut through spears, variations in bed height etc.
So for about six to eight weeks a year we have the opportunity to run the prototype asparagus harvester on a real asparagus field… if we could find one. It seems that asparagus growers have a couple of problems with testing machines on their fields. First, they earn their money from the asparagus crop, so if your machine doesn’t work well the farmer looses money, and second, it used to upset the crews that picked the asparagus.
There were a few years that worked out, when we would find a farmer that would allow us to cut a couple of rows on the edge of his field. One year a farmer told us we could have an acre well in advance of the season. One week after we got the harvester into his field he changed his mind and tossed us out. Not much testing done that year.
Another time the president of the asparagus growers association told us he would provide us with several acres the next season. When the season arrived he kept putting us off and finally told us he couldn’t find us any acreage. Great.
Part of the problem was that the asparagus growers did not really want to see mechanization come to the asparagus industry. I remember one grower who told me that he hoped that it would be a very expensive machine. The growers were making great money and were afraid mechanization would attract more growers and the increase volume would lower prices.
Now days it’s different. The much lower production costs of our foreign competitors has nearly wiped out the asparagus industry, and if mechanization doesn’t come along soon there will be nothing left. We will get all of our asparagus from Peru and Mexico.
After we hooked up with Washington State University things were different. The University paid farmers for the seasons crop, and any crop we harvested we turned over to the farmer every day anyway. The grower made out like a bandit.
The farmers are also much more interested in mechanical harvesting. The need to find a way to compete with the cheap imports and mechanization is really their only hope. So now they are rooting for us… and if we pay them enough they will let us experiment with our selective mechanical asparagus harvester on their farm.
To be continued…
Thursday, December 17, 2009
The Asparagus Harvester Invention – Trouble with cutting.
The Asparagus Harvester Invention – Trouble with cutting.
The harvester invention has been quite a challenge, and here are some more of the difficulties we had to overcome in the development of the machine.
Now that I’ve described some of the problems with sensing the spears and locating their positions on the bed, I’ll move on to the problems we had with actually cutting the spears.
For those of you who are unfamiliar with how asparagus grows, here is a little background. Asparagus is a fern, and the spears we eat are shoots that come up out of the ground and each of the little triangular shaped “brachs” at the tip of the spear will eventually become fern branches, unless you eat the spear first.
Once planted, the asparagus plant will stay in the ground and produce spears for about 15 years or so. Each spring you harvest the spears, and then let the plant become a fern. In the next spring you chop down all the fern, and once the weather gets warm enough the plants start sending up the shoots or spears.
If you cut the spears down before they can become a fern, the root mass or “crown” as it is called, which is about 6 inches below the top of the soil sends up more shoots. As long as you keep cutting the spears, the crown will continue to send up new ones. However, the root mass uses stored carbohydrates to supply the spears with food, and so you don’t want to cut the spears for too long or the crown will run out of food and become damaged.
A bed of asparagus ready for harvest looks like a forest of spears coming up randomly over the bed. The spears are all different heights and can grow more than 6 inches a day which requires you to harvest the field every day when its warm and growth is high.
Often spears are quite close together, and at substantially different heights.
The asparagus harvester can not stop to cut a spear, it must cut the spears as it travels through the field. Speed is critical because unlike most crops that you harvest once and move on to the next field, with asparagus you have to harvest the same field every day.
To avoid damaging spears that are not yet tall enough to harvest and close to a harvestable spear the blades must move very rapidly. Our harvester has blades mounted on the end of the piston rod of an air cylinder with a stroke of about 20 inches. Our cylinders can do the entire 20 inch stroke out and all the way back in less than 2 tenths of a second. It takes less than a tenth of a second to complete the extension part of the stroke.
Even so, since the asparagus harvester will be moving forward at 20 or 30 inches per second, in a tenth of a second the machine will have moved forward 3 inches. The faster the cylinder the less likely it will be to damage a spear that isn’t tall enough to harvest.
Making an air cylinder travel very fast is easy enough in theory, but just try getting an air cylinder manufacturer to build you one. The speed of the cylinders is determined by two main factors, the mass that has to be accelerated, and the maximum flow through the air piping, valve orifices, and cylinder ports.
To accelerate a piston rod assembly you simply need a lot of force. The more force the higher the acceleration. Since acceleration is force divided by mass, ideally we want a light weight piston and rod assembly with a large piston area. The large piston area converts the air pressure into a large force.
It turns out accelerating the piston rod assembly occurs in the first inch or so of stroke, and then you’ve reached terminal velocity. The terminal velocity is limited by the flow rate of the air. We used high CV (flow factor) valves with ½ inch ports, ½” air hoses, to make sure we had the highest flow rate we could achieve. The limiting factor was the size of the ports in the air cylinders.
The first problem we encountered was the inability to find air cylinders with large enough ports. Trying to build our own cylinders was prohibitively expensive due to the low quantity involved and not having the specialized equipment that would help lower the cost. For a long time we used 1-1/2 inch bore cylinders with ¼” cylinder ports. Now we have found a company that will build us our custom designed cylinder for a reasonable price. The latest cylinder is a 1 inch bore cylinder with ½” ports.
Since the spears need to be cut at or below ground level the blade must inter the ground to a depth of several inches to be sure and cut through the spear. But since the machine is traveling forward at 20 to 30 inches per second it’s not difficult to put the piston rod into a bind, and then the cylinder does not retract. This drags the blade through the bed damaging spears and after a few feet bends the piston rod.
At first we tried folding blades on clevis mounts, and spring mounted blades, but those ideas did not work out. We finally put the air cylinders on pivot mounts so if they did not retract quickly enough they would not bind which solved that particular problem.
Another huge problem was keeping the air cylinder from self-destructing. We could reverse the air valve to stop the extend stroke before it bottomed out against the front head, but on the return stroke the piston would hit the rear cylinder head at about 250 inches per second. The result was stretched or broken tie rods. We tried all kinds of springs on the rear of the cylinder and on the front of the cylinder under the blade mount. Springs don’t hold up. Less than a days harvesting would break any spring, metal or rubber that we tried.
We tried hydraulic shock absorbers but they don’t respond quickly enough to handle a cylinder that can fire 5 times in one second. They are way too slow.
We finally found success by mounting an air cylinder in the rear head of the main cylinder to act as a gas spring. Even then the cylinders would still disassemble
The harvester invention has been quite a challenge, and here are some more of the difficulties we had to overcome in the development of the machine.
Now that I’ve described some of the problems with sensing the spears and locating their positions on the bed, I’ll move on to the problems we had with actually cutting the spears.
For those of you who are unfamiliar with how asparagus grows, here is a little background. Asparagus is a fern, and the spears we eat are shoots that come up out of the ground and each of the little triangular shaped “brachs” at the tip of the spear will eventually become fern branches, unless you eat the spear first.
Once planted, the asparagus plant will stay in the ground and produce spears for about 15 years or so. Each spring you harvest the spears, and then let the plant become a fern. In the next spring you chop down all the fern, and once the weather gets warm enough the plants start sending up the shoots or spears.
If you cut the spears down before they can become a fern, the root mass or “crown” as it is called, which is about 6 inches below the top of the soil sends up more shoots. As long as you keep cutting the spears, the crown will continue to send up new ones. However, the root mass uses stored carbohydrates to supply the spears with food, and so you don’t want to cut the spears for too long or the crown will run out of food and become damaged.
A bed of asparagus ready for harvest looks like a forest of spears coming up randomly over the bed. The spears are all different heights and can grow more than 6 inches a day which requires you to harvest the field every day when its warm and growth is high.
Often spears are quite close together, and at substantially different heights.
The asparagus harvester can not stop to cut a spear, it must cut the spears as it travels through the field. Speed is critical because unlike most crops that you harvest once and move on to the next field, with asparagus you have to harvest the same field every day.
To avoid damaging spears that are not yet tall enough to harvest and close to a harvestable spear the blades must move very rapidly. Our harvester has blades mounted on the end of the piston rod of an air cylinder with a stroke of about 20 inches. Our cylinders can do the entire 20 inch stroke out and all the way back in less than 2 tenths of a second. It takes less than a tenth of a second to complete the extension part of the stroke.
Even so, since the asparagus harvester will be moving forward at 20 or 30 inches per second, in a tenth of a second the machine will have moved forward 3 inches. The faster the cylinder the less likely it will be to damage a spear that isn’t tall enough to harvest.
Making an air cylinder travel very fast is easy enough in theory, but just try getting an air cylinder manufacturer to build you one. The speed of the cylinders is determined by two main factors, the mass that has to be accelerated, and the maximum flow through the air piping, valve orifices, and cylinder ports.
To accelerate a piston rod assembly you simply need a lot of force. The more force the higher the acceleration. Since acceleration is force divided by mass, ideally we want a light weight piston and rod assembly with a large piston area. The large piston area converts the air pressure into a large force.
It turns out accelerating the piston rod assembly occurs in the first inch or so of stroke, and then you’ve reached terminal velocity. The terminal velocity is limited by the flow rate of the air. We used high CV (flow factor) valves with ½ inch ports, ½” air hoses, to make sure we had the highest flow rate we could achieve. The limiting factor was the size of the ports in the air cylinders.
The first problem we encountered was the inability to find air cylinders with large enough ports. Trying to build our own cylinders was prohibitively expensive due to the low quantity involved and not having the specialized equipment that would help lower the cost. For a long time we used 1-1/2 inch bore cylinders with ¼” cylinder ports. Now we have found a company that will build us our custom designed cylinder for a reasonable price. The latest cylinder is a 1 inch bore cylinder with ½” ports.
Since the spears need to be cut at or below ground level the blade must inter the ground to a depth of several inches to be sure and cut through the spear. But since the machine is traveling forward at 20 to 30 inches per second it’s not difficult to put the piston rod into a bind, and then the cylinder does not retract. This drags the blade through the bed damaging spears and after a few feet bends the piston rod.
At first we tried folding blades on clevis mounts, and spring mounted blades, but those ideas did not work out. We finally put the air cylinders on pivot mounts so if they did not retract quickly enough they would not bind which solved that particular problem.
Another huge problem was keeping the air cylinder from self-destructing. We could reverse the air valve to stop the extend stroke before it bottomed out against the front head, but on the return stroke the piston would hit the rear cylinder head at about 250 inches per second. The result was stretched or broken tie rods. We tried all kinds of springs on the rear of the cylinder and on the front of the cylinder under the blade mount. Springs don’t hold up. Less than a days harvesting would break any spring, metal or rubber that we tried.
We tried hydraulic shock absorbers but they don’t respond quickly enough to handle a cylinder that can fire 5 times in one second. They are way too slow.
We finally found success by mounting an air cylinder in the rear head of the main cylinder to act as a gas spring. Even then the cylinders would still disassemble
Inventing an Asparagus Harvester – 30 Years of Prototypes
I first decided to invent a selective asparagus harvester in about 1972. I asked my dad one day if he knew of something that needed inventing… I was bored. He was a farmer and an asparagus grower. He told me they needed a mechanical asparagus harvester that would just harvest the ripe spears; a selective asparagus harvester.
Not knowing any better I decided I would build one. At the time I was about 21 years old, fresh out of the army, and pretty good with electronics. I had a ham radio license when I was about 13 years old, built my own transmitters and receivers, and could fix anything from a car radio to a color TV.
I had read about a new kind of imaging device, I think it was one of the first CCD chips. I don’t remember all of the details, but the camera had basically 16 rows and 16 columns of light sensitive elements, and I decided to use that to detect the height and location of the spears on the bed, and I would use blades attached to air cylinders aimed toward the ground at about a 45 degree angle. I used eight cylinders arranged in a row across the bed, and when the camera spotted a spear tall enough to cut, it would activate the valve and fire the air cylinder that was lined up with the same column as the spear.
A friend of mine and I built a little demonstration prototype that had a little gas powered air compressor built out of channel and angle iron and 4 motorcycle tires that we pushed by hand. It had the camera, air compressor, 4 cutting cylinders and a crude pickup device that would grip the spears as they were cut.
That first prototype was enough to interest a local machine shop that decided to take risk of developing a selective asparagus harvester. They hired me for $2000 a month to oversee the development and took a 50 percent share of the rights to the machine. We spent the next ten years working on it, coming up with a new prototype each year.
The camera turned out to be unsuitable for the task, and during those years I tried just about everything you could think of to detect those stubborn spears of asparagus. I tried little wire bales that hung down from above, beam-breaking photo electric sensors, retro-reflective optical sensors, magnetic switches with plastic paddles, and even a Reticon line scan CCD camera, but all had serious drawbacks.
I really wanted to try a laser for illuminating the spears due to the precise position information I could get by using a laser shooting across the bed. It would be able to give me much more accurate information about where the spear was located on the bed and it’s height. But at the time lasers were several thousand dollars, and not nearly rugged enough to mount on an asparagus harvester.
Asparagus spears can be very delicate, and on cold mornings it is very easy to break a spear by just nudging it a bit. So you really don’t want to use something that has to contact the spear to detect it. Using through-beam sensors required mounting the emitter and receiver at the height of the spear you wanted to harvest. If you wanted to cut nine inch spears you mounted the beams nine inches above the bed. Harvestable spears would range from nine inches to about 16 inches on hot days. The longer spears fortunately are harder to break.
We used extremely thin sensors to avoid touching the spears, but you could still see the occasional spear break as it made contact with the sensor itself.
Another problem with sensing the spears was the fact that asparagus spears can lean in any direction, and significantly throw off the targeting of the spear. At the point where the spear reaches the nine inches off of the bed, it can be several inches to one side or to the front or back of where the spear actually emerges from the ground. That makes it a whole lot harder to cut the spear. Especially if the blades are narrow.
In 1984 we gave up the project due to lack of interest on the part of the asparagus growers. The machine was a self-propelled 3 row selective asparagus harvester. It wasn’t perfect yet but it did harvest asparagus.
At that time we used beam-breaking for sensing the spears; I think they were 4-1/2 inch wide channels the spears had to pass through.
The sensing of the spears and locating them were not the only problems we had in developing a selective asparagus harvester.
My next blog entry will discuss the difficulties we had with the air cylinders. And some of the inventive ways we found to address the problems… and why most of them did not work.
The Old Inventor Guy
Not knowing any better I decided I would build one. At the time I was about 21 years old, fresh out of the army, and pretty good with electronics. I had a ham radio license when I was about 13 years old, built my own transmitters and receivers, and could fix anything from a car radio to a color TV.
I had read about a new kind of imaging device, I think it was one of the first CCD chips. I don’t remember all of the details, but the camera had basically 16 rows and 16 columns of light sensitive elements, and I decided to use that to detect the height and location of the spears on the bed, and I would use blades attached to air cylinders aimed toward the ground at about a 45 degree angle. I used eight cylinders arranged in a row across the bed, and when the camera spotted a spear tall enough to cut, it would activate the valve and fire the air cylinder that was lined up with the same column as the spear.
A friend of mine and I built a little demonstration prototype that had a little gas powered air compressor built out of channel and angle iron and 4 motorcycle tires that we pushed by hand. It had the camera, air compressor, 4 cutting cylinders and a crude pickup device that would grip the spears as they were cut.
That first prototype was enough to interest a local machine shop that decided to take risk of developing a selective asparagus harvester. They hired me for $2000 a month to oversee the development and took a 50 percent share of the rights to the machine. We spent the next ten years working on it, coming up with a new prototype each year.
The camera turned out to be unsuitable for the task, and during those years I tried just about everything you could think of to detect those stubborn spears of asparagus. I tried little wire bales that hung down from above, beam-breaking photo electric sensors, retro-reflective optical sensors, magnetic switches with plastic paddles, and even a Reticon line scan CCD camera, but all had serious drawbacks.
I really wanted to try a laser for illuminating the spears due to the precise position information I could get by using a laser shooting across the bed. It would be able to give me much more accurate information about where the spear was located on the bed and it’s height. But at the time lasers were several thousand dollars, and not nearly rugged enough to mount on an asparagus harvester.
Asparagus spears can be very delicate, and on cold mornings it is very easy to break a spear by just nudging it a bit. So you really don’t want to use something that has to contact the spear to detect it. Using through-beam sensors required mounting the emitter and receiver at the height of the spear you wanted to harvest. If you wanted to cut nine inch spears you mounted the beams nine inches above the bed. Harvestable spears would range from nine inches to about 16 inches on hot days. The longer spears fortunately are harder to break.
We used extremely thin sensors to avoid touching the spears, but you could still see the occasional spear break as it made contact with the sensor itself.
Another problem with sensing the spears was the fact that asparagus spears can lean in any direction, and significantly throw off the targeting of the spear. At the point where the spear reaches the nine inches off of the bed, it can be several inches to one side or to the front or back of where the spear actually emerges from the ground. That makes it a whole lot harder to cut the spear. Especially if the blades are narrow.
In 1984 we gave up the project due to lack of interest on the part of the asparagus growers. The machine was a self-propelled 3 row selective asparagus harvester. It wasn’t perfect yet but it did harvest asparagus.
At that time we used beam-breaking for sensing the spears; I think they were 4-1/2 inch wide channels the spears had to pass through.
The sensing of the spears and locating them were not the only problems we had in developing a selective asparagus harvester.
My next blog entry will discuss the difficulties we had with the air cylinders. And some of the inventive ways we found to address the problems… and why most of them did not work.
The Old Inventor Guy
Friday, December 4, 2009
A New Patent - How to get a Patent or Patent Protection
Getting a patent for a new hot water system
I filed for a new patent a few days ago. The patent is for an improved hot water delivery system for residential and commercial buildings.
The new hot water delivery system is capable of providing faster than normal hot water delivery to any fixture in a home or building, and only to that fixture where the hot water is needed.
The basic idea is to place a pump at the water heater which when running will create a pressure difference between the hot and cold water lines with the hot water lines having the larger pressure.
At each fixture a cross-over valve connects the hot and cold water lines. The valve has a controller which has a temperature sensor in contact with the water in the valve. Each valve controller also has a communications link with the pump.
When you want hot water at any particular fixture you activate the valve by pressing a button that is either hard wired to the valve or uses a radio frequency transmitter to activate the valve. The valves can get their power from either the house current or batteries. Batteries would be great for retro-fit installations. We estimate the battery life to be a minimum of two years using four AA cells per valve.
When you press the button activating the valve, it checks the temperature of the water at the fixture, and if the water is not already hot, the valve controller sends a signal to the pump to begin pumping. The valve controller also at the same time opens the valve between the hot and cold water lines. Thus hot water begins flowing from the water heater with the cooled off hot water in the hot water piping being sent back towards the water heater through the cold water line which hooks to the inlet of the water heater somewhere.
So basically that is the new invention. Let’s examine the steps I’ve taken for protection so far. In a future blog I will cover how the patent attorney and I worked out the details of the patent, especially the patent claims.
After my partner and I decided we had a good idea for a new product we knew we needed to get patent protection. My partner found a patent attorney through a relative, a lawyer working for a very large and expensive firm. But what the heck, hopefully we would be able to obtain a good solid patent that could be enforced in the market place.
Foreign patent protection is complex and expensive. Very expensive. We decided to stick to just he US and Canada. Canada adds about $1,500 to the cost of filing.
I don’ remember all of the costs at this point, I did not sign the checks, the company did. I will be looking them up and reporting on all the details as far as expenditures go in the near future.
Our patent lawyer explained to us that the least expensive way to get some form of patent protection on our new idea was to do what she called a “document dump”. We gave her documents that explained the invention in detail, and she did the “document dump” which serves as proof in a court of law of when we first thought of the idea. Of course we could have thought of it 10 years before that, but this is absolute proof that you had thought of if by at least the day of the dump.
The reason we went with that was we had no money to pursue a patent, and this was the least expensive way to obtain some protection.
More about patenting the new hot water system in a future blog.
Bill the old inventor guy.
I filed for a new patent a few days ago. The patent is for an improved hot water delivery system for residential and commercial buildings.
The new hot water delivery system is capable of providing faster than normal hot water delivery to any fixture in a home or building, and only to that fixture where the hot water is needed.
The basic idea is to place a pump at the water heater which when running will create a pressure difference between the hot and cold water lines with the hot water lines having the larger pressure.
At each fixture a cross-over valve connects the hot and cold water lines. The valve has a controller which has a temperature sensor in contact with the water in the valve. Each valve controller also has a communications link with the pump.
When you want hot water at any particular fixture you activate the valve by pressing a button that is either hard wired to the valve or uses a radio frequency transmitter to activate the valve. The valves can get their power from either the house current or batteries. Batteries would be great for retro-fit installations. We estimate the battery life to be a minimum of two years using four AA cells per valve.
When you press the button activating the valve, it checks the temperature of the water at the fixture, and if the water is not already hot, the valve controller sends a signal to the pump to begin pumping. The valve controller also at the same time opens the valve between the hot and cold water lines. Thus hot water begins flowing from the water heater with the cooled off hot water in the hot water piping being sent back towards the water heater through the cold water line which hooks to the inlet of the water heater somewhere.
So basically that is the new invention. Let’s examine the steps I’ve taken for protection so far. In a future blog I will cover how the patent attorney and I worked out the details of the patent, especially the patent claims.
After my partner and I decided we had a good idea for a new product we knew we needed to get patent protection. My partner found a patent attorney through a relative, a lawyer working for a very large and expensive firm. But what the heck, hopefully we would be able to obtain a good solid patent that could be enforced in the market place.
Foreign patent protection is complex and expensive. Very expensive. We decided to stick to just he US and Canada. Canada adds about $1,500 to the cost of filing.
I don’ remember all of the costs at this point, I did not sign the checks, the company did. I will be looking them up and reporting on all the details as far as expenditures go in the near future.
Our patent lawyer explained to us that the least expensive way to get some form of patent protection on our new idea was to do what she called a “document dump”. We gave her documents that explained the invention in detail, and she did the “document dump” which serves as proof in a court of law of when we first thought of the idea. Of course we could have thought of it 10 years before that, but this is absolute proof that you had thought of if by at least the day of the dump.
The reason we went with that was we had no money to pursue a patent, and this was the least expensive way to obtain some protection.
More about patenting the new hot water system in a future blog.
Bill the old inventor guy.
Wednesday, December 2, 2009
First Invention Blog - Testing the Waters
Ok all you wantabe inventors, I'm starting this blog to help you out. I have been inventing my whole life, beginning in the early 70s. I have over a dozen patents and I just filed for another patents a few days ago.
In this blog I plan to discuss all kinds of things relating to inventions. I'll relate things I've learned over the years, and new insights when I get them. Many of my patents are related to water heaters and hot water circulating systems with some other gadgets and gizmos thrown in.
Online marketing is another subject I will be delving into. I've done pretty well with SEO for some of my web sites, and we are selling one of my inventons online successfully.
One of my inventions is being made in China, and that will also provide fertile ground for blog posts. Lot's of nifty headache stories... LOL
I'll begin all of this with my next blog. For the time being I need to go finish setting up all the details for this new blog. Ugh!
In this blog I plan to discuss all kinds of things relating to inventions. I'll relate things I've learned over the years, and new insights when I get them. Many of my patents are related to water heaters and hot water circulating systems with some other gadgets and gizmos thrown in.
Online marketing is another subject I will be delving into. I've done pretty well with SEO for some of my web sites, and we are selling one of my inventons online successfully.
One of my inventions is being made in China, and that will also provide fertile ground for blog posts. Lot's of nifty headache stories... LOL
I'll begin all of this with my next blog. For the time being I need to go finish setting up all the details for this new blog. Ugh!
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