GB2043162A

GB2043162A - A radial piston machine

Info

Publication number: GB2043162A
Application number: GB8000013A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1979-02-02
Filing date: 1980-01-02
Publication date: 1980-10-01
Also published as: FR2448051B1; DK44880A; JPS55104581A; DK148637C; DK148637B; FR2448051A1; DE7902865U1; GB2043162B

Abstract

The invention relates to a radial piston machine (pump or motor) comprising a cylinder block (5) which is arranged for rotation on a fixed control journal (4). Recesses (20, 21) are arranged in the control journal serving as control ports which are connected to longitudinal bores (22, 23) formed in the control journal for the supply or discharge of a pressure medium. On both sides of the recesses (20, 21) narrow relief grooves (24, 25) extend which are interrupted in the region of the inner dead centre. Due to the sealing webs formed between the recesses and the relief grooves hydraulic pressure fields are built up in the region of the inner dead centre which compensate for the forces prevailing on the high pressure side due to the pump setting. <IMAGE>

Description

SPECIFICATION A radial piston machine State of the art The invention originates from a radial piston machine according to the type set forth in the main claim. With one such known machine the relief grooves in the region of both webs -that is to say in regions lying diametrally opposite one another-are interrupted. That has the disadvantage that the relief of forces in the adjustment direction, which are dependent on the set eccentricity, act in the wrong direction and can thus be very disadvantageous. Since, in the known machine, the opposite relief grooves must also be connected to one another through a bore, the machining work is also greater.

Advantages of the invention As opposed to this, the radial piston machine in accordance with the invention comprising the characterising features of the main claim has the advantage that manufacture is more simple and that the "wandering" pressure fields proceeding from the high pressure port can achieve a greater expansion in that region than over the remainder of the periphery. Thus, the above-mentioned forces are better compensated.

Advantageous further developments and improvements of the machine set forth in the main claim are made possible by the measures set forth in the sub-claims.

Drawing An embodiment of the invention is reproduced in the drawing and is described in detail in the following specification. Figure 1 shows a longitudinal section through a radial piston machine, Figure 2 is a section along the line ll-ll in Fig. 1 and Figure 3 is a modification.

Description of the embodiment The radial piston machine has a housing 1 which is closed by a housing cover 2. A control journal 4 is fixedly arranged in a bore 3 in the housing cover 2. A blind bore 6 is formed in a cylinder block 5 by means of which the block is guided on the control - journal 4. Moreover, at its end projecting out of the housing, it is mounted in a slide bearing 7.

Radially extending cylinder bores 8 are arranged in the cylinder block 5 in which bores pistons 9 are slidingly guided which are supported on the bearing surface 11 of a stroke ring 1 2 by slide shoes 10 to which they are pivotally connected. An adjusting nut 1 3 is fixed to the stroke ring 1 2 and in which an adjusting spindle 14 engages which is mounted in a bracket 1 5 fixed to the housing and is actuated by a hand wheel 16. A compression spring 1 7 exerts a return force on the stroke ring 1 2.

Figs. 2 and 3 show details of the construction of the control journal. Two recesses 20, 21 separated by webs 18, 19 and cooperat ing with the cylinder bores are formed diametrally opposite one another in the control journal 4, each recess being connected to a blind bore 22 or 23 extending longitudinally in the control journal 4 for the supply or discharge of pressure medium through transverse bores 22', 23'. Narrow relief grooves 24, 25 which are interrupted in the region of the inner dead centre IT, extend in a peripheral direction on both sides of the recesses 20, 21. A sealing web 30, 31, 32, 33 is located between a recess 20, 21 and an adjacent relief groove 24, 25.

On rotation of the cylinder block 5, the slide shoes 10 slide on the bearing surface 11 of the stroke ring 1 2 and urge the pistons 9 to perform stroke movements during which they withdraw pressure medium from a recess, for example 20, and discharge it into the other recess, for example 21. The length of the stroke of the pistons can be varied by displacing the stroke ring 1 2 which is effected by actuation of the hand wheel 1 6.

Through the gap between the control journal 4 and the bore 6 in the cylinder block 5, pressure medium flows from the recesses 20, 21 along the control journal and arrives mainly in the relief grooves 24, 25. The main hydraulic forces acting on the cylinder block in the direction of the piston axes and which are effective on the high pressure side, are substantially balanced by hydrostatic fields in the region of the recesses 20, 21 and of the sealing webs 30 to 33. However, forces still occur in the adjustment direction of the stroke ring and which are dependent on the set eccentricity thereof.In accordance with the invention, due to the fact that the relief grooves in the region of the inner dead centre IT-in which the above-mentioned forces oc curare interrupted the "wandering" pressure fields proceeding from the high pressure side can experience a greater expansion in the said region than over the remainder of the periphery of the control journal and balance the said forces.

As Fig. 2 shows, the relief grooves 24, 25 have the same depth overall; they can be produced for example by profile turning. At the inner dead centre, the relief grooves are interrupted reaching substantially up to the end of the recesses 20, 21.

As Fig. 3 shows, the relief grooves-now referenced 24', 25'can also be made eccentric in such a manner that likewise at the inner dead centre they are not connected to one another.

1. A radial piston machine comprising a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A radial piston machine State of the art The invention originates from a radial piston machine according to the type set forth in the main claim. With one such known machine the relief grooves in the region of both webs -that is to say in regions lying diametrally opposite one another-are interrupted. That has the disadvantage that the relief of forces in the adjustment direction, which are dependent on the set eccentricity, act in the wrong direction and can thus be very disadvantageous. Since, in the known machine, the opposite relief grooves must also be connected to one another through a bore, the machining work is also greater. Advantages of the invention As opposed to this, the radial piston machine in accordance with the invention comprising the characterising features of the main claim has the advantage that manufacture is more simple and that the "wandering" pressure fields proceeding from the high pressure port can achieve a greater expansion in that region than over the remainder of the periphery. Thus, the above-mentioned forces are better compensated. Advantageous further developments and improvements of the machine set forth in the main claim are made possible by the measures set forth in the sub-claims. Drawing An embodiment of the invention is reproduced in the drawing and is described in detail in the following specification. Figure 1 shows a longitudinal section through a radial piston machine, Figure 2 is a section along the line ll-ll in Fig. 1 and Figure 3 is a modification. Description of the embodiment The radial piston machine has a housing 1 which is closed by a housing cover 2. A control journal 4 is fixedly arranged in a bore 3 in the housing cover 2. A blind bore 6 is formed in a cylinder block 5 by means of which the block is guided on the control - journal 4. Moreover, at its end projecting out of the housing, it is mounted in a slide bearing 7. Radially extending cylinder bores 8 are arranged in the cylinder block 5 in which bores pistons 9 are slidingly guided which are supported on the bearing surface 11 of a stroke ring 1 2 by slide shoes 10 to which they are pivotally connected. An adjusting nut 1 3 is fixed to the stroke ring 1 2 and in which an adjusting spindle 14 engages which is mounted in a bracket 1 5 fixed to the housing and is actuated by a hand wheel 16. A compression spring 1 7 exerts a return force on the stroke ring 1 2. Figs. 2 and 3 show details of the construction of the control journal. Two recesses 20, 21 separated by webs 18, 19 and cooperat ing with the cylinder bores are formed diametrally opposite one another in the control journal 4, each recess being connected to a blind bore 22 or 23 extending longitudinally in the control journal 4 for the supply or discharge of pressure medium through transverse bores 22', 23'. Narrow relief grooves 24, 25 which are interrupted in the region of the inner dead centre IT, extend in a peripheral direction on both sides of the recesses 20, 21. A sealing web 30, 31, 32, 33 is located between a recess 20, 21 and an adjacent relief groove 24, 25. On rotation of the cylinder block 5, the slide shoes 10 slide on the bearing surface 11 of the stroke ring 1 2 and urge the pistons 9 to perform stroke movements during which they withdraw pressure medium from a recess, for example 20, and discharge it into the other recess, for example 21. The length of the stroke of the pistons can be varied by displacing the stroke ring 1 2 which is effected by actuation of the hand wheel 1 6. Through the gap between the control journal 4 and the bore 6 in the cylinder block 5, pressure medium flows from the recesses 20, 21 along the control journal and arrives mainly in the relief grooves 24, 25. The main hydraulic forces acting on the cylinder block in the direction of the piston axes and which are effective on the high pressure side, are substantially balanced by hydrostatic fields in the region of the recesses 20, 21 and of the sealing webs 30 to 33. However, forces still occur in the adjustment direction of the stroke ring and which are dependent on the set eccentricity thereof.In accordance with the invention, due to the fact that the relief grooves in the region of the inner dead centre IT-in which the above-mentioned forces oc curare interrupted the "wandering" pressure fields proceeding from the high pressure side can experience a greater expansion in the said region than over the remainder of the periphery of the control journal and balance the said forces. As Fig. 2 shows, the relief grooves 24, 25 have the same depth overall; they can be produced for example by profile turning. At the inner dead centre, the relief grooves are interrupted reaching substantially up to the end of the recesses 20, 21. As Fig. 3 shows, the relief grooves-now referenced 24', 25'can also be made eccentric in such a manner that likewise at the inner dead centre they are not connected to one another. CLAIMS

1. A radial piston machine comprising a rotary cylinder block which accommodates pistons supported on a stroke cam and slidingly guided in bores and which is mounted on a rigid control journal which has two recesses separated by webs and forming high and low pressure sides, to which recesses bores extending in the control journal lead for the supply and discharge of pressure medium and in which relief grooves are formed laterally of the recesses and extending in a peripheral direction, characterised in that, the relief grooves are interrupted only in the region of the inner dead centre lying at one of the webs.

2. A machine according to claim 1 characterised in that the relief grooves extend eccentrically with respect to the periphery of the control journal.

3. A machine according to claim 1 characterised in that the relief grooves have the same depth overall.

4. A radial piston machine substantially as herein described with reference to the accompanying drawings.

4. A machine according to one of claims 1 to 3 characterised in that the relief grooves are of relatively small width.