US3593621A

US3593621A - Hydraulic motor

Info

Publication number: US3593621A
Application number: US797595A
Authority: US
Inventors: Pierre A Praddaude
Original assignee: Poclain SA
Current assignee: Poclain SA
Priority date: 1968-02-07
Filing date: 1969-02-07
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20
Also published as: DE1905455B2; FR1563866A; ES363251A1; DE1905455C3; DE1905455A1; GB1261044A

Abstract

In a fluid motor comprising a rotary cylinder block, a plurality of pistons mounted in cylinders in the block and a distributor mounted in the cylinder block for controlling the flow of pressure fluid for operating the pistons, the distributor has at least three groups of fluid distributing ports, one group being connected permanently to either the main fluid supply conduit or the main fluid discharge conduit, and means are provided for connecting at least one of the other two groups selectively to one or the other of the said main fluid conduits so that all the pistons in the cylinder block operate continually at all speeds of the motor.

Description

United States Patent lnventor Pierre A. Praddaude Crepy-en-Valois, France Appl. No. 797,595 Filed Feb. 7, 1969 Patented July 20, 1971 Assignee Societe Anonyme Poclain Le Plessis-Belleville Oise, France Priority Feb. 7, 1968 France 139,018

HYDRAULIC MOTOR 10 Claims, 3 Drawing Figs.

US. Cl 91/498, 91/492, 91/448 lnt.Cl FOlb 1/06, F01 b 13/06 Field (Search 91/204, 205, 498, 492

[56] References Cited UNITED STATES PATENTS 2,160,612 5/1939 Alpern 91/204 3,296,937 1/1967 Guinot 91/205 Primary Examiner- Paul E. Maslousky Attorney-Mason, Fenwick and Lawrence ABSTRACT: In a fluid motor comprising a rotary cylinder block, a plurality of pistons mounted in cylinders in the block and a distributor mounted in the cylinder block for controlling the flow of pressure fluid for operating the pistons, the distributor has at least three groups of fluid distributing ports, one group being connected permanently to either the main fluid supply conduit or the main fluid discharge conduit, and means are provided for connecting at least one of the other two groups selectively to one or the other of the said main fluid conduits so that all the pistons in the cylinder block operate continually at all speeds of the motor.

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,QC 9 I/ b Invenlor PmnAubE Aflorneys This invention relates to an fluid motor of the ltind comprising a rotary cylinder block, a plurality of pistons mounted in cylinders in said block and a distributor mounted in said cylinder bloclt for controlling the flow of pressure fluid for operating said pistons, the distributor having a series of ports by means of which said cylinders can be selectively connected with a main fluid supply conduit and a main fluid discharge conduit. The distributor is normally disposed in said cylinder block coaxially with the shaft of the motor and may be of the so-called flat type or cylindrical type, the ports in the distributor being spaced circumferentially about the periphery of a cylinder depending upon the type of distributor.

Fluid motors provided with a cylindrical distributor adapted to permit the motor to be driven at different speeds with a given delivery of pressure fluid from a pump are already known, for example from our prior French Pat. No. 1,460,752. With such known motors certain pistons do not operate when the motor runs at maximum speed and whilst in such cases provisions are made to prevent overheating of the pistons a certain imbalance producing vibrations may result.

The main object of the present invention is to overcome this disadvantage and with this object in view the fluid motor according to the invention comprises a rotary cylinder block a plurality of pistons mounted in cylinders in said block and a distributor mounted in said cylinder bloclt coaxial with the shaft of the motor for controlling the flow of pressure fluid for operating said pistons, wherein said distributor is provided with at least three groups of ports arranged to be put into communication successively with the cylinders of said plurality of pistons, one of said groups of ports being permanently connected with a fluid supply or a fluid discharge conduit, whilst at least one of the other groups of ports can be connected selectively to one or other of said fluid supply or discharge conduits.

In order that the invention may be more clearly understood one particular embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. ii is an axial section of a motor according to the inventlon;

FIG. 2 is a sectional view on the line ll-Il of lFlG. l; and

F IG. 3 is a sectional view on the line III-Ill of FIG. 2.

Referring to these drawings the fluid motor comprises a rotary cylinder block ll having a plurality of radial cylinders 3 in which operate pistons 2. The pistons 2 are held in engagement with a system of rollers 41 which permanently engage undulat' ing cam surfaces 5 formed on the inner wall of the motor casing. Each of the cylinders 3 has a port in which, during rotation of the cylinder block 1, moves successively in front of channels 7 formed in the outer surface of a cylindrical distributor d mounted in the cylinder block i coaxial with the shaft of the motor. The channels 7 are distributed regularly around the periphery of the distributor 8 and certain of them are of greater width than others for the reason which will be apparent from the following description.

Slidably mounted in a cylindrical bore 9 within the distributor d is a slide valve it) having an annular channel ltlln formed therein intermediate its ends. The valve ill has a head portion 1% which forms a piston upon which pressure fluid, delivered through a conduit ll, acts to control movement of the valve against the action of a compression spring M housed in an axial bore in said valve.

In the cylindrical wall of the bore 9 three annular channels Il a, 9b, and 9c are formed. The first channel ha is in permanent communication with a main supply conduit 13 for pressure fluid and the last channel 90 is in communication with a main fluid discharge conduit 14 Port 115a connects conduit 13 with channel 9a and ports il5b and ll5c open into channels 9b and 90 respectively which communicate with channels 7a, 7b and 70 respectively.

Referring now to FIG. 3 there are twelve channels 7, six alternate channels 7a of which are connected with channel 9a whilst the other six are distributed in two axially spaced groups each including three channels 712 or 7c connected respectively with channels Elb or 90. it must be understood that the total number of channels 7 correspond to the number of undulating cam surfaces 5. Furthermore if, as is preferred, one of the main fluid conduits l3, lid is permanently connected with half of the channels 7, each of the groups may comprise any number of ports preferably distributed in a regular pattern within each group. Finally in addition to the channel 9a there may be provided more than two other channels each corresponding to a group of channels 7.

In the operation of the embodiment of the invention illustrated in the drawings, when the valve 10 is in the position as illustrated in FIG. l, fluid under pressure supplied to passageway llfil, will flow through annular channelQa of valve ill, passageways 15a and channels 70 in the distributor 8, into the cylinders 33 to urge the pistons 2 outwardly and cause the cylinder bloclt to rotate about its axis. As the ports 6 of the cylinders Ii pass out of communication with the channels 7a and into communication with channels 7b and 7c, the cam surface of the motor causes the pistons 2 to move inwardly and thus force the fluid within the cylinders to flow through channels 7b and 7c, passageways 115k and 150, and channels 9b and 90, into the discharge passageway lid. It will be noted that with the valve in the position as illustrated in FIG. 1, the annular channel We of the valve permits communication of the annular channels 9b and 9c of the distributor with the discharge passageway lid. Under such conditions the motor will operate at a reduced speed.

When it is desired to operate the motor at a higher speed, fluid under pressure is applied to the passageway 111 of the distributor to move the valve llll against the action of the spring l2, thus causing the annular channel We of the valve to intercommunicate the annular channels 9a and 9b of the distributor. Under such circumstances, fluid under pressure supplied to passageway 113 will be caused to flow through annular channels 9a and 9b, passageways 15a and 115b, and channels 7a and 712 into the cylinders 3 through the ports 6. As the port 6 of each cylinder 3 passes out of communication with a. channel 7a following a channel 7b, it communicates with a channel 7c to permit fluid within the cylinder to flow through channel 70, a passageway R50 and annular passageway 90, into discharge passageway lid. By communicating both of the groups of ports 7a and 7b with the supply of fluid under pressure, an increased amount of pressure is applied on the pistons 2, thus causing the cylinder block to rotate at an increased speed.

Whenever it is desired to operate the motor at the reduced speed again, the fluid under pressure applied to the passageway ill of the distributor, is removed thus causing the valve to move to the right under the influence of the spring 112 so that the annular channel 9b is isolated from the annular channel 9a and communicated with the channel 9c as illus trated in FIG. l. The above operation takes place as if the cylinder capacity of the motor had been so reduced that for a given supply of pressure fluid the rotational speed of the motor increased relative to the preceding operation. In the example illustrated the speed of the motor will have doubled since for each revolution of the motor each piston will have been effective once in two revolutions.

By reason of the arrangement according to the invention all pistons operate during each revolution of the motor and at the slowest speeds all the pistons operate at each of the undulating cam surfaces whereas at high speeds they operate at only certain of said undulating cam surfaces.

Preferably, and particularly when a reversing valve is provided in the main pressure fluid conduits for reversing and stopping the motor, two groups of ports in the distributor will be permanently connected with said main conduits, the other groups being connected selectively to each of said conduits as described above.

It must be understood that although the hydraulic motor described above comprises a cylindrical distributor housed within the cylinder block of the motor and arranged coaxially of its shaft, the invention can be applied equally well to a motor provided with a so-called flat distributor.

It must also be understood that the invention is not limited to the particular embodiment herein described but modification may be made without departing from the scope of the invention as defined in the appended claims. For example, a modified form of distributor may be provided, as explained above, and the number of groups of ports and the relationship between the number of ports in each group may be varied.

What I claim is:

l. A fluid motor comprising a housing, a distributor mounted on said housing, a cylinder block rotatably mounted on said distributor, said cylinder block having a plurality of cylinders, each provided with a piston operatively cooperable with a cam surface mounted on said housing, said distributor having at least three groups of passageways, communicable successively with each of said cylinders as said cylinder block rotates on said distributor, a first of said groups of passageways being communicable with a fluid supply passageway, a second of said groups of passageways being communicable with a fluid discharge passageway, and a valve operable to selectively communicate the third of said groups of passageways with said fluid supply or fluid discharge passageways.

2. A fluid motor according to claim 1 wherein the ports of said first group of passageways communicable with said cylinders, are spaced circumferentially, and alternatively relative to the ports of said second and third groups of passageways communicable with said cylinders.

3. A fluid motor according to claim 2 wherein the number of ports of said first group of passageways is equal to the total number of ports of said second and third groups of passageways.

4. A fluid motor according to claim 1 wherein said distributor is provided with first and second cylindrical surfaces, said cylinder block is rotatably mounted on said first cylinder surface, said valve is mounted on said second cylindrical surface, and the terminal ports of said groups of passageways in said distributor are provided on said surfaces.

5. A fluid motor according to claim 4 wherein said second cylindrical surface of said distributor is provided with three annular channels, each communicable with one of said groups of passageways in said distributor, and said valve has a cylindrical surface engageable with and movable along said second cylindrical surface of said distributor, having an annular channel communicable with one of said annular channels and selectively with one of the other two of said annular channels when said valve is moved axially.

6. A fluid motor comprising a rotary cylinder block, a plurality of pistons mounted in cylinders in said block and a distn'butor coaxially mounted in said cylinder block for controlling the flow of fluid under pressure supplied to said pistons, wherein said distributor is provided with a fluid supply passageway, a fluid discharge passageway and at least three groups of ports arranged to be placed into communication successively with each of the cylinders of said plurality of pistons, one of said groups of ports permanently communicating with one of said fluid supply and fluid discharge passageways, and at least one of the other of said groups of ports being selectively communicable with one of said fluid supply and fluid discharge passageways.

7. A fluid motor according to claim 6 wherein the ports of a first of said groups of ports permanently communicate with said fluid supply passageway and the ports of a second group of ports permanently communicate with said fluid discharge passageway, one of said first and second groups having a number of ports corresponding to the total number of ports of the other two groups of ports.

8. A fluid motor according to claim 6 wherein the ports of each group communicate with a se arate annular channel forme in an Inner wall of said dtstrl utor, and the selective communication of said channels is effected by a slide valve.

9. A fluid motor according to claim 6 wherein said one of said groups of ports includes a plurality of ports spaced circumferentially and alternatively between ports of the other groups of ports.

10. A fluid motor according to claim 8 wherein said slide valve normally is biased into a first position to communicate a second of said groups of ports with said fluid discharge passageway, and movable into a second position to communicate said second of said groups of ports with said fluid supply passageway.

Claims

1. A fluid motor comprising a housing, a distributor mounted on said housing, a cylinder block rotatably mounted on said distributor, said cylinder block having a plurality of cylinders, each provided with a piston operatively cooperable with a cam surface mounted on said housing, said distributor having at least three groups of passageways, communicable successively with each of said cylinders as said cylinder block rotates on said distributor, a first of said groups of passageways being communicable with a fluid supply passageway, a second of said groups of passageways being communicable with a fluid discharge passageway, and a valve operable to selectively communicate the third of said groups of passageways with said fluid supply or fluid discharge passageways.

6. A fluid motor comprising a rotary cylinder block, a plurality of pistons mounted in cylinders in said block and a distributor coaxially mounted in said cylinder block for controlling the flow of fluid under pressure supplied to said pistons, wherein said distributor is provided with a fluid supply passageway, a fluid discharge passageway and at least three groups of ports arranged to be placed into communication successively with each of the cylinders of said plurality of pistons, one of said groups of ports permanently communicating with one of said fluid supply and fluid discharge passageways, and at least one of the other of said groups of ports being selectively communicable with one of said fluid supply and fluid discharge passageways.

8. A fluid motor according to claim 6 wherein the ports of each group communicate with a separate annular channel formed in an inner wall of said distributor, and the selective communication of said channels is effected by a slide valve.