GB2091811A

GB2091811A - Rotary positive-displacement fluid machines

Info

Publication number: GB2091811A
Application number: GB8138811A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1981-01-27
Filing date: 1981-12-23
Publication date: 1982-08-04
Also published as: GB2091811B; DE3102535A1

Abstract

In a pump or motor of the externally- meshing gear type having two pairs of gears (17,18;28,29) with common shafts (34,35) mounted in bearings (21,32) on the outer sides of the gears, the centres of the shafts are supported by bearings (38,39) and pressure- loaded pistons (41,42), Figure 2 (not shown), abutting the radially outer surfaces of these bearings. The pistons are orientated so as to counter-balance the radial forces acting on the central portions of the shafts due the pressure of the working fluid on the gears. Pressure may be applied to the pistons from the high-pressure side of either of the pairs of gears by way of a non-return valve (47 or 48). <IMAGE>

Description

SPECIFICATION A gear machine (pump or motor) State of the art The invention originates from a gear machine according to the preamble to the main claim. Known double-circuit machines of that kind are normally composed of two individual gear machines, that is to say each pair of gear wheels is independently mounted whereby four bearings are required. This represents a very high outlay which not only leads to a large constructional size but also to relatively high costs.

Advantages ofthe invention As opposed to this, the gear machine in accordance with the invention comprising the characterising features of the main claim has the advantage that, with an identical function, the number of bearings can be reduced by one per pair of gears whereby constructional size and costs are reduced.

Advantageous further developments and improvements of the features 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 illustrated in the drawing and is described in detail in the following specification.

Figure 1 shows a longitudinal section through a gear machine and Figure2 is a section along II - II in Figure 1.

Description ofthe embodiment The gear machine consists of two housing portions 11, 12 between which is located an intermediate plate 13 and which are closed by housing covers 14, 15 at the ends remote from the intermediate plate.

The housing portion 11 has a recess 16 passing through it in which two gear wheels 17,18 mesh with one another in external engagement and their shaft journals 19, 20 remote from the intermediate plate are likewise mounted in a bearing member 21 arranged in the recess 16. The shaft journal 20 has an extension 23 which passes outwardly through a bore 24 in the housing cover 15 and serves for driving the machine when it is used as a pump and as a driving shaft when the machine is used as a motor. A sealing member 25 is located in a widened portion of the bore 24.

The housing portion 12 is formed just the same as the housing portion 11. It has a recess 27 passing through it in which two gear wheels 28, 29 mesh in external engagement, the shaftjournals 30,31 of which remote from the intermediate plate are mounted in a bearing member 32 engaging the housing cover 14.

The gear wheels 17, 28 are connected to one another by an integral shaft journal 34 and the gear wheels 18, 19 are connected to one another by an integral shaft journal 35. These shaft journals pass through bores 36, 37 in the intermediate plate 13. There they are mounted in bearing bushes 38,39. The bearing bushes 38,39 have considerable radial play in the bores 36,37. An hydraulic force Pacts on each of the gear wheels from the high pressure side - see Figure 2. In known manner, a high pressure bore 40,40' is provided for each pair of gear wheels - the high pressure bore 40 is shown in dotted lines in Figure 2 - as well as a low pressure bore extending coaxially opposite to the high pressure bore, which is not illustrated since it is well known.

Triple bearings for the shafts are statically unbalanced. This disadvantage is overcome in accordance with the invention by the fact that in the first place the bearing bushes 38, 39 are radially movable and moreover each bearing bush is supported by an hydraulically influenced piston 41,42. The pistons 41,42 are sealingly slidingly arranged in bores 43,44 formed in the intermediate plate 13 wherein the axial direction of these bores extends exactly in the direction of the resulting hydraulic forces P, however, the force acting from the pistons 41,42 is in the opposite direction thereto.The pressure influencing of the pistons 41, takes place through a bore 45 formed in the intermediate plate and extending partially between the bores 43, 44, the bore 45 being in communication with a transverse bore 46 likewise extending in the intermdiate plate 13 and penetrating into the high pressure bores 40,40'. A non return valve 47,48 which can open in a direction from the gear wheels towards the bore 45, is arranged on each side of the junction between the bore 45 and the bore 46. The bore 46 issues into the two high pressure bores 40, 41 whereby there is guaranteed that the respective higher pressure from one of the two machines is conveyed through the bore 45 into the bores 43,44. In this manner, there is a guarantee that a static balance of the triple bearing for the gear wheel journals is provided.

CLAIMS 1. A gear machine (pump or motor) comprising at least two pairs of gear wheels arranged at a distance from one another, with which is associated a common hydraulic circuit or a respective independent hydraulic circuit and the outermost shaft journals of which are mounted in fixed bearings and a bearing for each shaft is likewise provided between each pair of gear wheels, characterised in that, the bearing between the pairs of gear wheels is radially movable and that a pressure influenced piston acts on each bearing and its direction of influence extends in line with the hydraulic forces exerted on the gear wheels but acts in the opposite direction thereto.

2. A machine according to claim 1, characterised in that, the respective higher pressure in one of the hydraulic circuits acts on the piston through a non return valve.

3. A machine according to claim 1 and/or 2, characterised in that, each piston is sealingly slidingly guided in a bore and that a supply bore issues into the said bores which supply bore proceeds from a transverse bore connecting the high pressure sides and in which are arranged two non return valves which can open in a direction away from the high

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A gear machine (pump or motor) State of the art The invention originates from a gear machine according to the preamble to the main claim. Known double-circuit machines of that kind are normally composed of two individual gear machines, that is to say each pair of gear wheels is independently mounted whereby four bearings are required. This represents a very high outlay which not only leads to a large constructional size but also to relatively high costs. Advantages ofthe invention As opposed to this, the gear machine in accordance with the invention comprising the characterising features of the main claim has the advantage that, with an identical function, the number of bearings can be reduced by one per pair of gears whereby constructional size and costs are reduced. Advantageous further developments and improvements of the features 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 illustrated in the drawing and is described in detail in the following specification. Figure 1 shows a longitudinal section through a gear machine and Figure2 is a section along II - II in Figure 1. Description ofthe embodiment The gear machine consists of two housing portions 11, 12 between which is located an intermediate plate 13 and which are closed by housing covers 14, 15 at the ends remote from the intermediate plate. The housing portion 11 has a recess 16 passing through it in which two gear wheels 17,18 mesh with one another in external engagement and their shaft journals 19, 20 remote from the intermediate plate are likewise mounted in a bearing member 21 arranged in the recess 16. The shaft journal 20 has an extension 23 which passes outwardly through a bore 24 in the housing cover 15 and serves for driving the machine when it is used as a pump and as a driving shaft when the machine is used as a motor. A sealing member 25 is located in a widened portion of the bore 24. The housing portion 12 is formed just the same as the housing portion 11. It has a recess 27 passing through it in which two gear wheels 28, 29 mesh in external engagement, the shaftjournals 30,31 of which remote from the intermediate plate are mounted in a bearing member 32 engaging the housing cover 14. The gear wheels 17, 28 are connected to one another by an integral shaft journal 34 and the gear wheels 18, 19 are connected to one another by an integral shaft journal 35. These shaft journals pass through bores 36, 37 in the intermediate plate 13. There they are mounted in bearing bushes 38,39. The bearing bushes 38,39 have considerable radial play in the bores 36,37. An hydraulic force Pacts on each of the gear wheels from the high pressure side - see Figure 2. In known manner, a high pressure bore 40,40' is provided for each pair of gear wheels - the high pressure bore 40 is shown in dotted lines in Figure 2 - as well as a low pressure bore extending coaxially opposite to the high pressure bore, which is not illustrated since it is well known. Triple bearings for the shafts are statically unbalanced. This disadvantage is overcome in accordance with the invention by the fact that in the first place the bearing bushes 38, 39 are radially movable and moreover each bearing bush is supported by an hydraulically influenced piston 41,42. The pistons 41,42 are sealingly slidingly arranged in bores 43,44 formed in the intermediate plate 13 wherein the axial direction of these bores extends exactly in the direction of the resulting hydraulic forces P, however, the force acting from the pistons 41,42 is in the opposite direction thereto.The pressure influencing of the pistons 41, takes place through a bore 45 formed in the intermediate plate and extending partially between the bores 43, 44, the bore 45 being in communication with a transverse bore 46 likewise extending in the intermdiate plate 13 and penetrating into the high pressure bores 40,40'. A non return valve 47,48 which can open in a direction from the gear wheels towards the bore 45, is arranged on each side of the junction between the bore 45 and the bore 46. The bore 46 issues into the two high pressure bores 40, 41 whereby there is guaranteed that the respective higher pressure from one of the two machines is conveyed through the bore 45 into the bores 43,44. In this manner, there is a guarantee that a static balance of the triple bearing for the gear wheel journals is provided. CLAIMS

1. A gear machine (pump or motor) comprising at least two pairs of gear wheels arranged at a distance from one another, with which is associated a common hydraulic circuit or a respective independent hydraulic circuit and the outermost shaft journals of which are mounted in fixed bearings and a bearing for each shaft is likewise provided between each pair of gear wheels, characterised in that, the bearing between the pairs of gear wheels is radially movable and that a pressure influenced piston acts on each bearing and its direction of influence extends in line with the hydraulic forces exerted on the gear wheels but acts in the opposite direction thereto.

3. A machine according to claim 1 and/or 2, characterised in that, each piston is sealingly slidingly guided in a bore and that a supply bore issues into the said bores which supply bore proceeds from a transverse bore connecting the high pressure sides and in which are arranged two non return valves which can open in a direction away from the high pressure side towards the supply bore.

4. A machine according to one of claims 1 to 3, characterised in that, the bearing members formed as bearing bushes are arranged in an intermediate plate which is arranged between the two housing portions accommodating the gear wheels.

5. A machine according to one of claims 1 to 4, characterised in that, the gear wheels directly engage the intermediate plate and the free shaft journals are mounted in bearing members arranged in the housing portions.

6. A gear pump or motor substantially as herein described with reference to the accompanying drawings.