GB2032010A

GB2032010A - A slide shoe for hydrostatic piston machines

Info

Publication number: GB2032010A
Application number: GB7927575A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-09-21
Filing date: 1979-08-08
Publication date: 1980-04-30
Also published as: JPS5543296A; FR2436919A1; DE2841008A1; GB2032010B

Abstract

A slide shoe 10 for a hydrostatic piston machine is pivotally connected to a delivery piston 12 of the machine. In use, hydrostatic pressure fields are built up on the slide sole 14 at groove- like recesses 21, 22, by pressure medium from the high pressure side of the machine with a throttling effect through a bore 16 extending in the piston. The recesses consist of at least two grooves lying behind one another on both sides of the centre and extending transversely with respect to the direction of movement of the slide shoe, which grooves are in communication with the bore and do not touch the edge of the slide shoe. <IMAGE>

Description

SPECIFICATION A slide shoe for hydrostatic piston machines STATE OF THE ART The invention originates from a slide shoe according to the type set forth in the main claim.

Such a slide shoe has already been proposed in which, however, the groove-like recesses for the most part extend in the longitudinal direction of the slide shoe or are continuous. However, only average results having regard to the hydraulic support (= unloading) are achieved therewith.

ADVANTAGES OF THE INVENTION As opposed to this, the slide shoe in accordance with the invention comprising the characterising features of the main claim has the advantage that especially good results are achieved in respect of the production of hydrostatic and hydrodynamic pressure fields and also the unloading of the slide shoes.

Advantageous further developments and improvements of the slide shoe set forth in the main claim, are made possible by the measures set forth in the sub-claims. It has proved to be of special advantage when the groove-like recesses are made H-shaped, lie symmetrically in the slide shoe sole and the two parallely extending grooves extend in the direction of travel of the slide shoe.

DRAWING An embodiment of the invention is illustrated in the drawing and is described in more detail in the following specification. Figure 1 shows a longitudinal section through a slide shoe together with a piston, Figures 2 to 7 are modifications of the embodiment according to Figure 1, Figures 8 to 12 show a second embodiment.

DESCRIPTION OF THE EMBODIMENTS A piston 12 which is sealingly slidingly arranged in a piston bore 13, is supported on the spherical head 11 of the slide shoe 10 of Figure 1.

The slide sole 14 of the slide shoe slides on the track 1 5 of a stroke generating member. A longitudinal bore 1 6 passes through the slide shoe and is in communication with the bore 1 7 in the piston 12. The bore 1 6 or 1 7 includes a throttle 16', 1 7'. A small amount of pressure medium flows through the bores 1 6, 17 out of the piston bore to the slide sole and at that location builds up an hydrostatic pressure field. Figure 2 shows the slide sole of the above-described slide shoe and close by an arrow which indicates the direction of travel of the slide shoe. In the centre of the slide sole a longitudinal groove 20 is formed in the direction of movement which extends substantially over one-third of the length of the entire slide sole.The bore 1 6 in the slide shoe issues into the centre of the said longitudinal groove. A respective transverse groove 21, 22 which does not, however, extend up to the edge of the slide shoe sole, is formed at each end of the longitudinal groove. As the name already implies, these transverse grooves extend at right angles to the direction of movement of the slide shoe.

Moreover, at the two narrow ends of the slide shoe sole, somewhat rectangular or square shallow recesses 23, 24 are also formed the depth of which is only slight which also applies to the grooves 20 to 22.

Through the pressure medium flowing through the bore 16, an hydrostatic pressure field is built up in the grooves 20 to 22, even at low speeds.

However, with increasing relative speed between the slide shoe and the stroke generating track 15, an increasing hydrodynamic bearing pressure is also built up at the slide shoe sole. At high relative speeds the dynamic bearing pressure clearly predominates over the hydrostatic pressure. The hydrodynamic bearing pressure exists predominantly on the smooth areas of the slide sole. The recesses 23, 24 limit the hydrostatic bearing pressure.

The embodiments according to Figures 3 to 5 differ from that according to the embodiment of Figure 2 simply by the fact that at the ends of the transverse grooves 21,22 short longitudinal grooves 25 to 27 are formed extending in the direction of movement which either extend towards one another or extend away from one another, or both. The hydrostatic pressure field is somewhat increased thereby.

The embodiments according to Figures 6 and 7 differ from that according to Figure 2 simply by the fact that instead of the rectangular shallow recesses 23, 24, transverse grooves 28, 29 are provided which extend over the entire width of the slide sole and lie in the vicinity of the transverse grooves 21, 22. In the embodiment according to Figure 7 the transverse grooves - now referenced 30 and 31 - do not extend over the entire width and moreover are in communication with longitudinal grooves 32, 33 which extend up to the end of the slide sole.

Moreover, in the embodiment according to Figure 8, two transverse grooves 34, 35 are provided as in the embodiment according to Figure 2, which are now not connected to one another. A bore 36, 37 which proceeds from the piston bore 1 6 - see Figure 1 2 - issues into each one of the said transverse grooves.

Moreover, the shallow recesses 23, 24 are formed at the ends. The embodiments according to Figures 9 to 11 differ from that according to Figure 8 by the fact that short grooves 38, 39, 40 extending in a longitudinal direction are provided at the ends of the transverse grooves 34, 35 and indeed just as in the embodiments according to Figures 3 to 5.

The arrangement according to Figures 8 to 11 has the advantage that action against a tilting movement of the slide shoe in the direction of travel is effected by the two independent hydrostatic fields.

1. A slide shoe for hydrostatic piston machines on the slide sole of which hydrodynamic and hydrostatic pressure fields are active, wherein the

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A slide shoe for hydrostatic piston machines STATE OF THE ART The invention originates from a slide shoe according to the type set forth in the main claim. Such a slide shoe has already been proposed in which, however, the groove-like recesses for the most part extend in the longitudinal direction of the slide shoe or are continuous. However, only average results having regard to the hydraulic support (= unloading) are achieved therewith. ADVANTAGES OF THE INVENTION As opposed to this, the slide shoe in accordance with the invention comprising the characterising features of the main claim has the advantage that especially good results are achieved in respect of the production of hydrostatic and hydrodynamic pressure fields and also the unloading of the slide shoes. Advantageous further developments and improvements of the slide shoe set forth in the main claim, are made possible by the measures set forth in the sub-claims. It has proved to be of special advantage when the groove-like recesses are made H-shaped, lie symmetrically in the slide shoe sole and the two parallely extending grooves extend in the direction of travel of the slide shoe. DRAWING An embodiment of the invention is illustrated in the drawing and is described in more detail in the following specification. Figure 1 shows a longitudinal section through a slide shoe together with a piston, Figures 2 to 7 are modifications of the embodiment according to Figure 1, Figures 8 to 12 show a second embodiment. DESCRIPTION OF THE EMBODIMENTS A piston 12 which is sealingly slidingly arranged in a piston bore 13, is supported on the spherical head 11 of the slide shoe 10 of Figure 1. The slide sole 14 of the slide shoe slides on the track 1 5 of a stroke generating member. A longitudinal bore 1 6 passes through the slide shoe and is in communication with the bore 1 7 in the piston 12. The bore 1 6 or 1 7 includes a throttle 16', 1 7'. A small amount of pressure medium flows through the bores 1 6, 17 out of the piston bore to the slide sole and at that location builds up an hydrostatic pressure field. Figure 2 shows the slide sole of the above-described slide shoe and close by an arrow which indicates the direction of travel of the slide shoe. In the centre of the slide sole a longitudinal groove 20 is formed in the direction of movement which extends substantially over one-third of the length of the entire slide sole.The bore 1 6 in the slide shoe issues into the centre of the said longitudinal groove. A respective transverse groove 21, 22 which does not, however, extend up to the edge of the slide shoe sole, is formed at each end of the longitudinal groove. As the name already implies, these transverse grooves extend at right angles to the direction of movement of the slide shoe. Moreover, at the two narrow ends of the slide shoe sole, somewhat rectangular or square shallow recesses 23, 24 are also formed the depth of which is only slight which also applies to the grooves 20 to 22. Through the pressure medium flowing through the bore 16, an hydrostatic pressure field is built up in the grooves 20 to 22, even at low speeds. However, with increasing relative speed between the slide shoe and the stroke generating track 15, an increasing hydrodynamic bearing pressure is also built up at the slide shoe sole. At high relative speeds the dynamic bearing pressure clearly predominates over the hydrostatic pressure. The hydrodynamic bearing pressure exists predominantly on the smooth areas of the slide sole. The recesses 23, 24 limit the hydrostatic bearing pressure. The embodiments according to Figures 3 to 5 differ from that according to the embodiment of Figure 2 simply by the fact that at the ends of the transverse grooves 21,22 short longitudinal grooves 25 to 27 are formed extending in the direction of movement which either extend towards one another or extend away from one another, or both. The hydrostatic pressure field is somewhat increased thereby. The embodiments according to Figures 6 and 7 differ from that according to Figure 2 simply by the fact that instead of the rectangular shallow recesses 23, 24, transverse grooves 28, 29 are provided which extend over the entire width of the slide sole and lie in the vicinity of the transverse grooves 21, 22. In the embodiment according to Figure 7 the transverse grooves - now referenced 30 and 31 - do not extend over the entire width and moreover are in communication with longitudinal grooves 32, 33 which extend up to the end of the slide sole. Moreover, in the embodiment according to Figure 8, two transverse grooves 34, 35 are provided as in the embodiment according to Figure 2, which are now not connected to one another. A bore 36, 37 which proceeds from the piston bore 1 6 - see Figure 1 2 - issues into each one of the said transverse grooves. Moreover, the shallow recesses 23, 24 are formed at the ends. The embodiments according to Figures 9 to 11 differ from that according to Figure 8 by the fact that short grooves 38, 39, 40 extending in a longitudinal direction are provided at the ends of the transverse grooves 34, 35 and indeed just as in the embodiments according to Figures 3 to 5. The arrangement according to Figures 8 to 11 has the advantage that action against a tilting movement of the slide shoe in the direction of travel is effected by the two independent hydrostatic fields. CLAIMS

1. A slide shoe for hydrostatic piston machines on the slide sole of which hydrodynamic and hydrostatic pressure fields are active, wherein the hydrostatic pressure field formed substantially at only groovelike recesses is provided with pressure medium from the cylinder space through at least one bore characterised in that the recesses consist of at least two grooves lying behind one another on both sides of the centre and extending transversely with respect to the direction of movement of the slide shoe, which grooves are in communication with the bore and do not touch the edge of the slide shoe.

2. A slide shoe according to claim 1 characterised in that the two transversely extending grooves are connected by a longitudinal groove extending in the direction of movement of the slide sole, in such a manner that an H-shaped groove outline exists which lies symmetrically in the slide sole.

3. A slide shoe according to claim 1 andlor 2 characterised in that the bore issues into the longitudinal groove.

4. A slide shoe according to one of claims 1 to 3 characterised in that short grooves extending in a longitudinal direction and which are adjacent one another or remote from one another are formed at the ends of the transverse grooves.

5. A slide shoe according to one of claims 1 to 4 characterised in that substantially rectangular or square recesses of slight depth are formed at the two ends of the slide sole and indeed viewed in the direction of travel.

6. A slide shoe according to one of claims 1 to 5 characterised in that between the ends located in the direction of travel of the slide shoe and the transversely extending grooves a respective other transversely extending groove is formed which extends either over the entire width of the slide sole or only over a portion thereof wherein, in the latter case, a longitudinal groove extends to each of the ends of the slide sole.

7. A slide shoe according to one of claims 1 to 5 characterised in that the bores issuing into the transverse grooves proceed from the bore in the slide shoe.

8. A slide shoe substantially as herein described with reference to Figures 1 and 2, Figure 1 modified in accordance with any one of Figures 3 to 7, Figures 8 and 12 or Figure 12 modified in accordance with any one of Figures 9 to 11, of the accompanying drawings.