US3713367A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluid pressure operated motors
Assignee: Butterworth Hydraulic Developments Ltd
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Filing: 1971-08-27
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Granted: 1973-01-30
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Expires: 1991-08-27
Abstract
Abstract A fluid operated motor having a reciprocating piston with two opposed different effective areas of which the smaller effective area is open to continuous fluid pressure in a constant pressure chamber to pressure bias the piston in one axial direction, the larger effective area communicates with an alternating pressure chamber and in which reciprocation of the piston is achieved by alternately fluid pressurizing and exhausting the alternating pressure chamber by control of valve means which valve means further acts to open communication between the constant pressure and alternating pressure chambers when the piston is moving against its axial biasing so that fluid displaced from the constant pressure chamber enters the alternating pressure chamber. The motor also including a variable volume chamber which is open to exhaust and expands as the piston moves in its bias direction and contracts as the piston moves against its bias direction and the valve means still further acts to open communication between the variable volume chamber and alternating pressure chamber when the variable volume chamber is expanding and to close such communication when the variable volume chamber is contracting so that fluid from the contracting variable volume chamber is delivered to exhaust to alleviate intermittent exhaust back pressure in the motor. An embodiment of the invention includes the motor in a percussive device.
Inventors
- 👤 P Butterworth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:06
CPC Classifications
F; F01; F01B; F01B11/00; F01B11/04; Y; Y10; Y10S; Y10S173/00; Y10S173/04
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
315 words
A fluid pressure operated reciprocating motor which includes; a pressure biased piston axially slidable in a piston cylinder, the piston having different effective areas of which the larger effective area defines with one part of the piston cylinder an alternating pressure piston chamber and the smaller effective area defines with another part of the piston cylinder a constant pressure piston chamber which constant pressure piston chamber is in permanent communication with a fluid pressure inlet so that when the inlet is connected to a source of fluid under pressure the piston is biased for movement in one sense of axial direction; valve means adapted to connect alternately the alternating pressure piston chamber with fluid pressure inlet and exhaust to reciprocate the piston when the inlet is connected to a source of fluid under pressure, said valve means further being adapted to open communication between the constant pressure piston chamber and the alternating pressure piston chamber when the piston is moving in the direction against its bias so that fluid displaced from the constant pressure piston chamber is fed back into the alternating pressure piston chamber; a variable volume chamber which is in substantially continual communication with exhaust and is controlled by the piston so as to expand or contract as the case may be when the piston moves in the direction of or against its bias respectively; and wherein the said valve means acts to close and open communication alternately between the alternating pressure chamber and the said variable volume chamber so that exhaust fluid from the alternating pressure piston chamber can enter the expanding said variable volume chamber when the piston is moving in the direction of its bias and that, when the piston is moving in the direction against its bias, fluid from the contracting said variable volume chamber is delivered directly to exhaust to alleviate intermittent exhaust back pressure in the motor.
Claim 2
Dependent Claim
315 words
A fluid pressure operated reciprocating motor which includes; a pressure biased piston axially slidable in a piston cylinder, the piston having different effective areas of which the larger effective area defines with one part of the piston cylinder an alternating pressure piston chamber and the smaller effective area defines with another part of the piston cylinder a constant pressure piston chamber which constant pressure piston chamber is in permanent communication with a fluid pressure inlet so that when the inlet is connected to a source of fluid under pressure the piston is biased for movement in one sense of axial direction; valve means adapted to connect alternately the alternating pressure piston chamber with fluid pressure inlet and exhaust to reciprocate the piston when the inlet is connected to a source of fluid under pressure, said valve means further being adapted to open communication between the constant pressure piston chamber and the alternating pressure piston chamber when the piston is moving in the direction against its bias so that fluid displaced from the constant pressure piston chamber is fed back into the alternating pressure piston chamber; a variable volume chamber which is in substantially continual communication with exhaust and is controlled by the piston so as to expand or contract as the case may be when the piston moves in the direction of or against its bias respectively; and wherein the said valve means acts to close and open communication alternately between the alternating pressure chamber and the said variable volume chamber so that exhaust fluid from the alternating pressure piston chamber can enter the expanding said variable volume chamber when the piston is moving in the direction of its bias and that, when the piston is moving in the direction against its bias, fluid from the contracting said variable volume chamber is delivered directly to exhaust to alleviate intermittent exhaust back pressure in the motor.
Claim 3
Dependent Claim
315 words
A fluid pressure operated reciprocating motor which includes; a pressure biased piston axially slidable in a piston cylinder, the piston having different effective areas of which the larger effective area defines with one part of the piston cylinder an alternating pressure piston chamber and the smaller effective area defines with another part of the piston cylinder a constant pressure piston chamber which constant pressure piston chamber is in permanent communication with a fluid pressure inlet so that when the inlet is connected to a source of fluid under pressure the piston is biased for movement in one sense of axial direction; valve means adapted to connect alternately the alternating pressure piston chamber with fluid pressure inlet and exhaust to reciprocate the piston when the inlet is connected to a source of fluid under pressure, said valve means further being adapted to open communication between the constant pressure piston chamber and the alternating pressure piston chamber when the piston is moving in the direction against its bias so that fluid displaced from the constant pressure piston chamber is fed back into the alternating pressure piston chamber; a variable volume chamber which is in substantially continual communication with exhaust and is controlled by the piston so as to expand or contract as the case may be when the piston moves in the direction of or against its bias respectively; and wherein the said valve means acts to close and open communication alternately between the alternating pressure chamber and the said variable volume chamber so that exhaust fluid from the alternating pressure piston chamber can enter the expanding said variable volume chamber when the piston is moving in the direction of its bias and that, when the piston is moving in the direction against its bias, fluid from the contracting said variable volume chamber is delivered directly to exhaust to alleviate intermittent exhaust back pressure in the motor.
Claim 4
Dependent Claim
315 words
A fluid pressure operated reciprocating motor which includes; a pressure biased piston axially slidable in a piston cylinder, the piston having different effective areas of which the larger effective area defines with one part of the piston cylinder an alternating pressure piston chamber and the smaller effective area defines with another part of the piston cylinder a constant pressure piston chamber which constant pressure piston chamber is in permanent communication with a fluid pressure inlet so that when the inlet is connected to a source of fluid under pressure the piston is biased for movement in one sense of axial direction; valve means adapted to connect alternately the alternating pressure piston chamber with fluid pressure inlet and exhaust to reciprocate the piston when the inlet is connected to a source of fluid under pressure, said valve means further being adapted to open communication between the constant pressure piston chamber and the alternating pressure piston chamber when the piston is moving in the direction against its bias so that fluid displaced from the constant pressure piston chamber is fed back into the alternating pressure piston chamber; a variable volume chamber which is in substantially continual communication with exhaust and is controlled by the piston so as to expand or contract as the case may be when the piston moves in the direction of or against its bias respectively; and wherein the said valve means acts to close and open communication alternately between the alternating pressure chamber and the said variable volume chamber so that exhaust fluid from the alternating pressure piston chamber can enter the expanding said variable volume chamber when the piston is moving in the direction of its bias and that, when the piston is moving in the direction against its bias, fluid from the contracting said variable volume chamber is delivered directly to exhaust to alleviate intermittent exhaust back pressure in the motor.
Claim 5
Dependent Claim
137 words
A motor as claimed in claim 1 wherein the variable capacities of the constant pressure piston chamber, the alternating pressure piston chamber and the said variable volume chamber are so related that when the alternating pressure piston chamber is expanding, the volume of fluid displaced from the constant pressure piston chamber in a given time is substantially equal to the volume of fluid entering the alternating pressure piston chamber less the volume of fluid displaced from the said variable volume chamber in that time; and that when the alternating pressure piston chamber is contracting the volume of fluid entering the constant pressure piston chamber in a given time is substantially equal to the volume of fluid displaced from the alternating pressure piston chamber less the volume of fluid entering the said variable volume chamber in that time.
Claim 6
Dependent Claim
78 words
A motor as claimed in claim 1 wherein the said variable volume chamber is defined by a secondary piston and cylinder device which device is operatively connected to the main piston and cylInder device which defines the constant and alternating pressure piston chambers to provide required sequential expansion and contraction of the said variable volume chamber in accordance with expansion and contraction of the constant pressure piston chamber during axial movement of the main piston in its cylinder.
Claim 7
Dependent Claim
19 words
A motor as claimed in claim 1 wherein the piston defines with its cylinder the said variable volume chamber.
Claim 8
Dependent Claim
164 words
A motor as claimed in claim 4 wherein the piston cylinder has a stepped bore and the piston carries two piston lands, the first, which is located in the larger bore of the piston cylinder, has differential effective end areas and effectively constitutes a part of the pressure biased piston proper, and the second, which is located in the smaller bore of the piston cylinder, effectively constitutes part of a pumping piston; and wherein the alternating pressure piston chamber is formed between the end of the larger piston cylinder bore and the outwardly facing end of the first piston land, the said variable volume chamber is formed between the end of the smaller piston cylinder bore and the outwardly facing end of the second piston land, and the continuous pressure piston chamber is constituted by the annulus defined by the wall of the stepped bore between the inwardly facing end of the first piston land and the opposed face of the second piston land.
Claim 9
Dependent Claim
68 words
A motor as claimed in claim 1 wherein the said valve means is provided by a single valve which is operatively controlled by movement of the piston and is adapted to alternately open and close communication between the alternating pressure piston chamber and the constant pressure piston chamber and concurrently to respectively close and open communication between the said variable volume chamber and the alternating pressure piston chamber.
Claim 10
Dependent Claim
38 words
A motor as claimed in claim 1 wherein the said valve means comprises a spool which reciprocates in a spool cylinder and in which the spool and piston mutually control reciprocation of each other in their respective cylinders.
Claim 11
Dependent Claim
144 words
A motor as claimed in claim 7 wherein a land of the spool controls the opening and closing of a port in the spool cylinder which is in permanent communication by way of a piston signalling passage with the alternating pressure piston chamber and movement of the spool is operatively associated with movement of the piston so that when the spool is located at one end of its stroke the piston signalling passage communicates by way of the spool cylinder with fluid pressure inlet whereby the piston is caused to move in the direction against its bias and when the spool is located at the other end of its stroke the piston signalling passage communicates by way of the spool cylinder both with exhaust and with the said variable volume chamber whereby the piston is caused to move in the direction of its bias.
Claim 12
Dependent Claim
165 words
A motor as claimed in claim 7 wherein the said valve means comprises a pressure biased spool axially slidable in the spool cylinder, the spool having different effective areas of which the larger effective area defines with one part of the spool cylinder an alternating pressure spool chamber and the smaller effective area defines with another part of the spool cylinder a constant pressure spool chamber which constant pressure spool chamber is in permanent communication with fluid pressure inlet so that when the inlet is connected to a source of fluid under pressure the spool is biased for movement in one sense of direction; and wherein the alternating pressure spool chamber is adapted to communicate by way of spool signalling passage means with port means controlled by movement of the piston which port means is, during reciprocation of the piston, controlled to communicate alternately with fluid inlet and exhaust so that the alternating pressure spool chamber is alternately pressurized and exhausted to reciprocate the spool.
Claim 13
Dependent Claim
65 words
A motor as claimed in claim 9 wherein the port means of the spool signalling passage means is controlled by a land of the piston so that at one end of the stroke of the piston said port means communicates with fluid inlet and at the other end of the stroke said port means communicates with exhaust by way of the said variable volume chamber.
Claim 14
Dependent Claim
37 words
A motor as claimed in claim 9 wherein at one end of stroke of the piston, the port means of the spool signalling passage means communicate with fluid inlet by way of the constant pressure piston chamber.
Claim 15
Dependent Claim
104 words
A motor as claimed in claim 1 wherein the said variable volume chamber is in substantially continual communication with exhaust by way of a port which is capable of being closed by a pumping piston which partly defines said variable volume chamber when the said pumping piston is at its end of stroke in a sense to contract said variable volume chamber, so that, when said port in the variable volume chamber is closed by said pumping piston, fluid is trapped in the said variable volume chamber and said trapped fluid acts to arrest the said pumping piston at its said end of stroke.
Claim 16
Dependent Claim
92 words
A motor as claimed in claim 7 wherein the spool when moving in at least one sense of axial direction is adapted to displace fluid from an arresting chamber by way of a port which is capable of being closed by the spool at its end of stroke in said one sense of axial direction so that, when said port in the arresting chamber is closed by the spool, fluid is trapped in the said arresting chamber and said trapped fluid acts to arrest the spool at its said end of stroke.
Claim 17
Dependent Claim
142 words
A motor as claimed in claim 13 in which the spool has two spool rods, one at each end thereof, each spool rod being axially slidable in a blind bore, and wherein two arresting chambers are provided, one at each end of the spool, the arresting chambers being formed between the ends of the spool rods and the closed end part lengths of the blind bores in which the spool rods are respectively slidable, the arresting chambers each having a port which communicates with exhaust and is controlled by the respective spool rod to be closed to trap fluid in that arresting chamber immediately prior to the spool reaching its end of stroke in a sense to contract that arresting chamber so that the spool is arrested at both ends of its stroke by the fluid trapped in the respective arresting chambers.
Claim 18
Dependent Claim
154 words
A motor as claimed in claim 1 wherein fluid pressure flow into, and fluid displaced from, the alternating pressure piston chamber is by way of two ports in the piston cylinder, one of said two ports being restricted and located to be in permanent communication with the alternating pressure piston chamber and the other of said two ports being located to be closed by the piston at its end of stroke in a sense to contract the alternating pressure piston chamber so that when the said other of said two ports is closed by the piston as the alternating pressure piston chamber is contracted, fluid is displaced from the alternating pressure piston chamber solely by way of the said restricted port which imparts a throttling action on said displaced fluid and provides a degree of arresting on the piston at its end of stroke in said sense to contract the alternating pressure piston chamber.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |