GB Patent: GB-181,503,922
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| High pressure steam engine
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Patentee:
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| Richard Trevithick (exact or similar names) - Camborne, county Cornwall, England |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Granted: |
Jun. 05, 1815 |
Espacenet patent
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Joel Havens
Wikipedia biography of Richard Trevithick
Grace's Guide page on Richard Trevithick
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Description: |
| This is the patent for Trevithick's plunger pole engine, which is now almost forgotten but was an important advance at the time."Instead of a piston working in the main cylinder of the steam engine, I do use a plunger pole, similar to those employed in pumps for lifting water; and I do make the said plunger pole of nearly the same diameter as the working cylinder, leaving only space enough between the pole and the cylinder to prevent friction; or in case the steam is admitted near the stuffing box, I leave sufficient room for the steam to pass to the bottom of the cylinder."And I do make at the upper end of the cylinder, for the plunger pole to pass through, a stuffing box, of much greater depth than usual; into which stuffing box I do introduce enough of the usual packing to fill it one-third high. Upon this packing I place a ring of metal, occupying about another third of the depth of the stuffing box; this ring having a circular groove at the inside, and a hole or holes through it, communicating with the outside, and with a hole through the side of the stuffing box; or instead of one ring, containing a groove, I sometimes place two thinner rings, kept asunder by a number of pillars to about the distance of one-third of the depth of the stuffing box; and I pack the remaining space above the ring or rings, and secure the whole down in the usual manner. The intention of this arrangement is to produce the effect of two stuffing boxes, allowing a space between the two stuffings for water to pass freely in from the boiler or forcing pump through a pipe, and through the hole in the side of the stuffing box, so as to surround the plunger pole, and form the ring of water, for the purpose of preventing the escape of steam, by keeping up an equilibrium between the water above the lower stuffing and the steam in the cylinder. By this part of my said invention I obviate the necessity of that tight packing which is requisite when steam of a high pressure is used, and consequently I avoid a greater proportion of the usual friction, because a very moderate degree of tightness in the packing is quite sufficient to prevent the passage of any injurious quantity of so dense a fluid as water."According to William Pole's "A Treatise on the Cornish Pumping Engine", the first such engine was built at Herland in 1815, with a plunger pole 33 inches in diameter.The plunger pole engine worked well enough when new but the pole was prone to wear from the high-pressure steam leaking around it, which caused a downward spiral of performance. In addition, the large surface area of the plunger pole absorbed quite a bit of energy from the steam, reducing efficiency.In 1816 Trevithick went to South America for an extended visit related to mining interests. Before he left he sold the patents rights to William Sims, a Cornwall engineer. |
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