US3910162A

US3910162A - Force compensating arrangement for a radial piston machine

Info

Publication number: US3910162A
Application number: US353625A
Authority: US
Inventors: Gerhard Nonnenmacher
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1972-04-22
Filing date: 1973-04-23
Publication date: 1975-10-07
Anticipated expiration: 1992-10-07
Also published as: CH549727A; DE2219881A1; FR2182480A5; JPS4921701A; GB1398485A

Abstract

The rotor of a radial piston pump has cylinders, and pistons cooperating with an eccentric actuating ring so that the resultant of the inward directed forces passes through the axis of the actuator ring at an angle less than 90* to a plane through the axes of the rotor and of the actuator ring. The high pressure and low pressure control ports on the control pintle supporting the rotor, are angularly displaced relative to this plane so that the resultant of outward directed pressure forces, which passes through the rotor axis, is parallel to the resultant of the inwardly directed forces, and compensates the same.

Description

United States Patent [191 Nonnenmacher Oct. 7, 1975 FORCE COMPENSATING ARRANGEMENT FOR A RADIAL PISTON MACHINE [75] Inventor: Gerhard Nonnenmacher,Korntal,

211 App]. No.: 353,625

[30] Foreign Application Priority Data Apr. 22, 1972 Germany 2219881 3,188,918 6/1965 Bjorklund 91/497 3,192,867 7/1965 Bjorklund et a]. 3,408,948 11/1968 Boyd 91/498 FOREIGN PATENTS OR APPLICATIONS 775,853 5/1957 United Kingdom 91/498 Primary Examiner-William L. Freeh Attorney, Agent, or FirmMichael S. Striker [57] ABSTRACT The rotor of a radial piston pump has cylinders, and pistons cooperating with an eccentric actuating ring so that the resultant of the inward directed forces passes through the axis of the actuator ring at an angle less than 90 to a plane through the axes of the rotor and of the actuator ring. The high pressure and low pressure control ports on the control pintle supporting the rotor, are angularly displaced! relative to this plane so that the resultant of outward directed pressure forces, which passes through the rotor axis, is parallel to the resultant of the inwardly directed forces, and compensates the same.

1 Claim, 5 Drawing Figures US. Patent Oct. 7,1975 Sheet1of3 3,910,162

U.S. Patent Oct 7,1975

Sheet 2 of 3 TI s US. Patent 0a. 7,1975 Sheet 3 of3 3,910,162

FORCE COMPENSATING ANGENIENT FOR A RADIAL PISTON MACHINE BACKGROUND OF THE INVENTION The US. Pat. No. 3,064,583 discloses a radial piston i Chine, which may operate as a pump,

machine, pump or hydraulic motor with a rotor mounted on a control pintle having partcircular high pressure and low pressure control ports cooperating during rotation with cylinder ports provided at the inner ends of passages which are connected with the cylinders, respectively. In machines of this type, forces pressing the rotor on the high pressure side against the control pintle are compensated by corresponding pressure areas, but it has been found that substantial forces occur in the direction of the eccentricity of the actuator ring, which are not compensated. This has the result that due to the one sided forces, increased wear of the parts occurs, so that the span of life of the machine is reduced.

SUMMARY OF THE INVENTION It is an object of the invention to provide the radial piston machine in which all occurring forces are compensated so that the operation and span of life of the machine are improved.

With this object in view, the present invention provides a radial piston machine in which the cylinder ports on the inner surface of the rotor are circumferentially displaced to lead the cylinders during rotation while the machine operates asa pump, for example, while the high pressure and low pressure control ports on the pintle are angularly displaced relative to a plane passing through the axes of the rotor and of the actuator ring so that the high pressure control port is moved toward the inner dead center position of the rotor in which the rotor is closest spaced from the actuator ring.

In such an arrangement, the inner relieving pressure area on the control pintle is turned so that its direction conforms to the resultant of the forces acting on the bearings of the rotor.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The inventionitself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic cross-sectional view illustrating a first embodiment of the invention;

FIG. 2 is a schematic cross sectional view illustrating a second embodiment of the invention;

FIG. 3 is partially a cross-sectional view corresponding to FIG. I, and partially a diagram illustrating the inwardly directed forces produced by the eccentric actuator ring;

FIG. 4 is a cross-sectional view illustrating a radial piston machine according to the prior art; and

FIG. 5 is a cross-sectional view of the embodiment of FIG. I, and including a diagrammatic illustration of the compensation of the resultant of the inwardly directed mechanical forces by the resultant of outwardly di rected pressure forces in accordance with the invention.

DESCRIPTION OF THEPREFERRED EMBODIMENTS As shown in FIGS. 1, 3 and 5, a radial piston ma has a control pintle 10 surrounded by the inner cylindrical surface 11a of a rotor 11, and supporting rotor 11 for rotation about an axis A,. A stationary actuator ring 14 has an inner cylindrical surface 14a having an axis A parallel with rotor axis A and spaced therefrom the distance e representing the eccentricity of the actuator ring 14 in relation to the rotor 11.

Rotor 11 has six cylinders 15 with radial axes, not

shown, in which spherical pistons 16 are mounted for" radial movement, and abut the. inner surface 14a of the actuator ring 14. During rotation in the direction of the i arrow 0, each piston 16 passes successively through i the inner dead center point Ti and the outer dead center point Ta of plane B. Rotor 11 is closer to the actuator ring 14 at the inner dead center point Ti than at the outer dead center point Ta.

The cylinders 15 do not directly communicate with the

control ports

12 and 13, but are connected with the same by cylinder passages 18 which have inner ports 18a sweeping the

control ports

12 and 13.

In the embodiment of FIGS. 1, 3 and 5, the passages 18 are parallel to the radial axes of the respective cylinders which intersect the rotor axis A Assuming that the machine operates as a pump in the direction of the arrow 0, the axes of the cylinder passages 18 lead the axes of the respective cylinders 17.

In the embodiment illustrated in FIG. 2, the rotor passages 18' which open in ports on the inner surface llla' of rotor 11', are slanted to the radial axes of the respective cylinders 15 so that the outer end of each rotor passage 18 is concentric with the bottom face 17 while the cylinder port 18' leads the radial axis of the respective cylinder 15 in the same position as the cylinder ports 18a in the embodiment of FIG. 1.

When the machine is operated as a pump,

rotor

11 or 11 is driven in the direction of the arrow 0. After passing through the inner dead center point Ti, the pistons 16 suck pressure medium through the low pressure control portll3 and the cylinder passages 18 into the radial cylinders 15, and displace the pressure medium, after passing through the outer dead center point Ta, into the high pressure control port 112. Between the

rotor

11, 11 and the control pintle 10, pressure areas develop due to pressure medium leaking out of the control ports18a. The outwardly directed forces of the pressure areas, compensate the inwardly directed forces acting on the rotor 11 due to the fact that in accordance with the invention, the axial plane of symmetry E of the

control ports

12 and 13 is angularly displaced from the plane B, particularly when the

cylinder ports

18a and 18a are displaced relative to the radial axes of the cylinders 15, as will now be explained with reference to FIGS. 3 to 5.

FIG. 3 illustrates the embodiment of FIG. 1, but it will be understood that the diagram shown in FIG. 3 is also applicable to the embodiment of FIG. 2.

Referring now to FIG. 3, in the angular regions a, and a which are bounded by the plane 13 and by a plane C perpendicular to plane B and intersecting the same in the rotor axis A at any time the same number of pistons 16 is located due to the equal angular spacing of the axes of cylinders 15. In the regions ,8, and B which are bounded by plane B and by plane D passing through the axis A; perpendicular to plane B, on the average, more pistons I6 are located in the region B; than in the region 3 Since the inwardly acting mechanical forces P act always perpendicularly to the inner cylin drical surface 14a of the actuator ring 14, the inwardly directed forces in the region 8 exceed on the average the inwardly directed forces B in the region [3,. Accordingly the resultant P of the inwardly directed mechanical forces P in the pressure region is not perpendicular to the plane B, but defines therewith an angle less than 90 in the region of the inner dead center point Ti.

FIG. 4 shows a radial piston pump according to the prior art with a rotor 11' and high pressure and low pressure pressure ports 12' and 13' in the control pintle 10 which are arranged symmetrically to the plane B which passes through the axes A and A In the machine of FIG. 4, the outwardly directed forces of control pindle I acting on rotor 11" have a resultant P perpendicular to the plane B and passing through axis A,. Consequently, the outwardly directly resultant P of the arrangement of the prior art, cannot fully compensate the resultant P of the inwardly directed mechanical forces, described with reference to FIG. 3.

In the arrangement of the present invention as shown in FIG. 5, the

control ports

12 and 13 are displaced in circumferential direction so-that the resultant vector P which passes through the axis A,, is substantially parallel to the resultant P of the inwardly directed mechanical forces. Consequently, the two opposite resultant forces P and P fully compensate each other.

In order to prevent influencing of the timing of the flow into and out of the cylinder ports 180, the ports 18a are displaced relative to the cylinders 15. The

control ports

12 and 13 are geometrically arranged on opposite sides of a second plane E which passes through the rotor axis A at an angle to the plane B. The control ports 18a may be displaced relative to the axis of the respective cylinders 15, the same angular distance. The angle between the planes E and B may be the same as the angle between the plane D and the resultant force As compared with the prior art construction shown in FIG. 4, the high pressure control port 12 is angularly displaced toward the inner dead center point Ti, which is determined by the position of the actuator ring 14.

During operation as a pump, the rotor 11 rotates in the direction of the arrow 0 shown in FIG. 1. When the machine is to be used as a hydraulic motor, fluid under high pressure is supplied through the control pintle to the high pressure port 12 which causes rotation of the rotor 11 in the opposite counterclockwise direction.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of piston pumps and hydraulic motors differing from the types described above.

While the invention has been illustrated and described as embodied in a force compensating arrangement for a radial piston machine in which control ports and cylinder ports are angularly displaced as compared with the conventional arrangement, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspexts of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. Force compensating arrangement for a radial piston machine, comprising a control pintle having an outer cylindrical surface formed with diametrically disposed circumferentially extending high pressure and low pressure control ports; a rotor having an inner cylindrical surface mounted on said outer cylindrical surface for rotation about a first axis, said rotor including equally angularly spaced cylinders having radial cylinder axes intersecting said first axis and cylinder ports on said inner cylindrical surface communicating with said control ports, and pistons in said cylinders; and an actuator ring surrounding said rotor and having an inner cylindrical actuator surface in sliding contact with said pistons and having a second axis, said first and said second axes being parallel and located in a first axial plane so that said rotor has in said first plane inner and outer dead centerpoints closest to, and farthest from, respectively, said actuator surface whereby a resultant of inwardly directed forces passes through said second axis defining a predetermined angle less than with said first plane in the region of said inner dead center point, said high pressure and low pressure control ports being symmetrical to a second plane passing through said first axis and defining such an angle with said first plane so that the resultant of the outward directed pressure forces passing through said first axis is substantially parallel and equal to said resultant of said inward directed pressure forces for compensating the same, said cylinder ports being circumferentially displaced relative to said radial cylinder axes, respectively, an angle which is substantially equal to said angle between said first and second planes.

Claims

1. Force compensating arrangement for a radial piston machine, comprising a control pintle having an outer cylindrical surface formed with diametrically disposed circumferentially extending high pressure and low pressure control ports; a rotor having an inner cylindrical surface mounted on said outer cylindrical surface for rotation about a first axis, said rotor including equally angularly spaced cylinders having radial cylinder axes intersecting said first axis and cylinder ports on said inner cylindrical surface communicating with said control ports, and pistons in said cylinders; and an actuator ring surrounding said rotor and having an inner cylindrical actuator surface in sliding contact with said pistons and having a second axis, said first and said second axes being parallel and located in a first axial plane so that said rotor has in said first plane inner and outer dead center points closest to, and farthest from, respectively, said actuator surface whereby a resultant of inwardly directed forces passes through said second axis defining a predetermined angle less than 90* with said first plane in the region of said inner dead center point, said high pressure and low pressure control ports being symmetrical to a second plane passing through said first axis and defining such an angle with said first plane so that the resultant of the outward directed pressure forces passing through said first axis is substantially parallel and equal to said resultant of said inward directed pressure forces for compensating the same, said cylinder ports being circumferentially displaced relative to said radial cylinder axes, respectively, an angle which is substantially equal to said angle between said first and second planes.