Gearbox

Abstract

A hydraulic pump arrangement (1), has a hydraulic pump (2) with two flow directions. The hydraulic pump (2) has a first hydraulic port (3) and a second hydraulic port 4. A first feed line (5) and a first discharge line (6) are, both connected to the first hydraulic port (3). A second feed line (7) and a second discharge line (8), are both connected to the second hydraulic port (4). A non-return valve (9, 10, 11, 12) is arranged in each feed line (5, 7) and in each discharge line (6, 8).

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 102011055194.1, filed Nov. 10, 2011. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The disclosure relates to a gearbox with a hydraulic pump arrangement that has a hydraulic pump with two flow directions. The hydraulic pump has a first hydraulic port and a second hydraulic port. In this case, the hydraulic pump arrangement is formed such that it functions independent of rotational direction. Accordingly, hydraulic fluid is delivered through a discharge in both possible flow directions.

BACKGROUND

A hydraulic pump arrangement is known from DE 10 2010 010804 A1. The disclosed hydraulic pump is arranged in a housing flange portion of a gearbox. The housing flange portion covers a recess of the gearbox housing. The housing flange portion has an axially projecting extension where several modules of the hydraulic pump are arranged axially one behind the other. Furthermore, bores and valves are provided in the housing flange portion, which enables delivery of the hydraulic fluid independent of the rotational direction.

SUMMARY

It is object of the present disclosure, to provide a specifically simple structure for a rotational independent hydraulic connection of the hydraulic pump arrangement.

The object is achieved by a gearbox with a hydraulic pump arrangement that comprises a hydraulic pump with two flow directions. The hydraulic pump has a first hydraulic port and a second hydraulic port. The hydraulic pump arrangement includes a first feed and a first discharge, both of which are connected to the first hydraulic port. A second feed and a second discharge are connected to the second hydraulic port. A non-return valve is arranged in each feed and in each discharge.

The feeds of the hydraulic pump arrangement are connected to an oil sump of the gearbox. Thus, oil can be delivered from the oil sump of the gearbox to the lubricating points of the gearbox or to further components to be lubricated.

The hydraulic pump is driven by a drive shaft of the gearbox. The drive shaft of the gearbox includes at least one gear. The gearbox has a gearbox housing with a housing bottom. The oil sump is arranged in the housing bottom. An accommodation chamber is provided in the housing bottom to accommodate the gear of the drive shaft. The accommodation chamber separates the oil sump into a first sump chamber and into a second sump chamber. The first feed of the hydraulic pump arrangement is connected to the first sump chamber. The second feed of the hydraulic pump arrangement is connected to the second sump chamber.

The non-return or check valves in the feeds open in the direction to the respective hydraulic port. The non-return or check valves in the discharges close in the direction to the respective hydraulic port. If the hydraulic pump is driven in one direction where the suction side is at the first hydraulic port and the pressure side is at the second hydraulic port, the non-return valve in the first feed opens. The non-return valve in the first discharge closes, as this is laid out to close in the direction to the first hydraulic port. Thus, hydraulic fluid is sucked in from the first feed. On the pressure side, at the second hydraulic port, the non-return valve at the first discharge opens. The non-return valve in the second feed closes, as this only opens in the direction to the second hydraulic port. Thus, it is closed by the hydraulic pressure against this direction.

In the other case, where the hydraulic pump is driven such, that the pressure side occurs at the first hydraulic port and the suction side occurs at the second hydraulic port, the non-return valve in the first feed is closed and the non-return valve in the first discharge opens. However, the non-return valve in the second feed is opened and the non-return valve in the second discharge is closed. Thus, hydraulic fluid is pumped from the second feed to the first discharge.

In a preferred embodiment, both discharges are connected to a joint discharge line. Thus, the hydraulic pump arrangement has only one discharge line and one discharge port in spite of the two discharges. Preferably, the hydraulic pump is a gear pump, a vane pump or a piston pump.

The two sump chambers can be connected to each other via a connection passage. The accommodation chamber for the gear of the drive shaft is necessary for a compact design. The gear of the drive shaft has to be arranged as close as possible to the lower gearbox bottom of the gearbox housing. This means, however, that without an accommodation chamber, the gear of the drive shaft would enter the oil of the oil sump and would catapult the oil upwards due to rotation. In this case the danger exists that air would be sucked in by the oil pump because of the agitated oil. To prevent this, the accommodation chamber extends up to the level of the oil sump or just below the oil level of the oil sump. Thus, the oil that flows to lubricate the gears of the gearbox flows, downwards due to gravity, partially directly into the oil sump and also into the accommodation chamber. In the accommodation chamber, the oil is then catapulted upward due to the rotation of the gear of the drive shaft. The oil is, preferably, catapulted over a wall of the accommodation chamber up to an outer wall of the gearbox housing. From here, the oil flows directly into the oil sump. No gear of the gearbox enters the oil in the oil sump. Thus, settling of the oil takes place and no danger exists that air will be sucked in by the hydraulic pump arrangement.

Preferably, the hydraulic pump has a pump housing, that is detachably connected to the gearbox housing. Thus, a compact design of the gearbox, including the hydraulic pump arrangement, is ensured. Alternatively, the pump housing can also form part of the gearbox housing, in the form of a housing extension.

The pump housing can have two inlet openings, that are connected to the bores in the gearbox housing leading to the sump chamber. The non-return valves of the feeds are arranged in the bores of the gearbox housing.

The hydraulic pump can be modularly constructed and can include an inlet module, a pump module and an outlet module. The modules are detachably connected to each other. Connection passages, that extend from inlets to the hydraulic pump, are provided as part of the feeds in the inlet module. The hydraulic pump, especially the gears of a gear pump, is provided in the pump module. In the outlet module, connection passages are provided as part of the discharges. The connection passages extend from the hydraulic pump to a joint outlet of the discharges. Thus, by a simple exchange of the individual modules, the hydraulic pump can be adapted to different requirements. Different large pump modules with different outputs can be provided. Thus, depending on the necessary delivery output, a corresponding pump module can be used. As the pump module is not part of the gearbox or of the gearbox housing, no special cast pieces need to be provided that have to be adapted to the different pump outputs. The individual modules are, respectively, encapsulated to the outside or sealed, so that they represent their own housing. Depending on the pump output, the whole hydraulic pump, consisting of the individual modules, will differ in length.

A pump drive shaft is provided for the drive of the hydraulic pump. The drive shaft is passed from the pump module to the inlet module. The pump drive shaft is passed through a bore in the gearbox housing and is, drive-wise, detachably connected within the gearbox housing to a drive shaft of the gearbox.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

In the following, a preferred embodiment is described in detail by using the drawings. It shows

FIG. 1 is a schematical representation of a hydraulic circuit of a hydraulic pump arrangement according to the disclosure;

FIG. 2 is a longitudinal sectional view through a portion of a gearbox with a hydraulic pump arrangement according to the disclosure;

FIG. 3 is an exploded view of the hydraulic pump arrangement of FIG. 2;

FIG. 4 is a cross-sectional view of a pump module of the hydraulic pump arrangement of FIG. 2;

FIG. 5 is a top plan view of an inlet module of the hydraulic pump arrangement of FIG. 2;

FIG. 6 is a cross-sectional view of the outlet module of the hydraulic pump arrangement of FIG. 2; and

FIG. 7 is a cross-sectional view of a portion of a gearbox of FIG. 2 in the area of the accommodation chamber.

DETAILED DESCRIPTION

In FIG. 1 the hydraulic circuit of a hydraulic pump arrangement 1, to achieve a pump effect independent of direction of rotation, according to the disclosure is schematically shown. The hydraulic pump arrangement 1 includes a hydraulic pump 2 in the form of a gear pump with a first hydraulic port 3 and a second hydraulic port 4. The first hydraulic port 3 is connected to a first feed line 5 and a first discharge line 6. The second hydraulic port 4 is connected to a second feed line 7 and a second discharge line 8. In each of the respective feed lines 5, 7 and discharge lines 6, 8 there is arranged a non-return or check valve 9, 10, 11, 12. The two feed lines 5, 7 are connected via a joint feed line or are separately connected to an oil sump 13 or to an oil reservoir. The two discharge lines 6, 8 are connected to a joint discharge line 14. Alternatively, for each discharge line 6, 8, also separate discharge lines can be provided. The non-return valve 9 in the first feed line 5 opens in the direction to the first hydraulic port 3. The check valve 9 closes in the direction towards the oil sump 13. The non-return valve 11 in the second feed 7 opens towards the second hydraulic port 4 and closes in the direction to the oil sump 13. Thus, the two non-return valves 9, 11 of the two feed lines 5, 7 open towards the hydraulic pump 2.

The non-return valve 10 in the second discharge line 8 opens towards the discharge line 14. The check valve 10 closes in the direction to the second hydraulic port 4. The non-return valve 12 of the first discharge line 6 opens in the direction to the discharge line 14 and closes in the direction to the first hydraulic port 3. Thus, the two non-return valves 10, 12 of the two discharge lines 6, 8 close, respectively, in the direction to the hydraulic pump 2 and open in the direction to the discharge line 14.

As indicated by the arrows of the hydraulic pump 2, the hydraulic pump 2 can be driven in two rotational directions. In a first rotational direction, hydraulic fluid is pumped from the first hydraulic port 3 to the second hydraulic port 4. The first hydraulic port 3 is, thus, the suction side and the second hydraulic port 4 is the pressure side. Thus, a vacuum is present at the first hydraulic port 3. The vacuum opens the non-return valve 9 of the first feed line 5 in the direction to the first hydraulic port 3. Furthermore, the non-return valve 12 of the first discharge line 6 is closed because of the vacuum at the first hydraulic port 3.

At the pressure side, the side of the second hydraulic port 4, the non-return valve 10 in the second discharge line 8 is opened because of excess pressure in the direction to the discharge line 14. At the same time, the non-return valve 11 of the second feed line 7 closes. Thus, the hydraulic fluid is delivered from the oil sump 13 through the first feed line 5 via the hydraulic pump 2, to the second discharge line 8 and further to the discharge line 14.

When the hydraulic pump 2 is driven in a second rotational direction, which is in an opposite direction to the first rotational direction, the suction side is produced at the second hydraulic port 4. The pressure side occurs at the first hydraulic port 3. Thus, the non-return valve 10 of the second discharge line 8 is closed because of the vacuum at the second hydraulic port 4 in direction to the hydraulic pump 2. Instead, the non-return valve 11 in the second feed line 7 is opened in direction to the second hydraulic port 4. Thus, hydraulic oil is delivered from the oil sump 13 via the second feed line 7 to the second hydraulic port 4. At the pressure side, the side of the first hydraulic port 3, the non-return valve 9 of the first feed line 5 is closed because of the excess pressure in direction to the oil sump 13. Furthermore, the non-return valve 12 of the first discharge line 6 is opened in direction to the discharge line 14. Thus, the hydraulic fluid is delivered from the first hydraulic port 3 via the first discharge line 6 to the discharge line 14.

Thus, depending on the rotational driving direction of the hydraulic pump 2, oil is delivered from the first feed line 5 to the second discharge line 8 or from the second feed line 7 to the first discharge line 6. However, in both directions it is ensured, that the oil is delivered from the oil sump 13 to the discharge line 14. Thus, oil is always delivered, independent of the rotational driving direction of the hydraulic pump 2.

FIG. 2 shows a partial cross-sectional view through a gearbox 15 with a gearbox housing 16. A drive shaft 18 with a gear 24 is, besides other shafts, rotatably supported in the gearbox housing 16. The drive shaft 18 exits in a sealed manner from the gearbox housing 16. The drive shaft 18 is formed as a hollow shaft. A drive trunnion 19 is inserted into the hollow shaft-like drive shaft 18. The drive trunnion 19 connects the drive shaft 18 to a drive unit for driving the gearbox 15. In this case, it is preferably a power-take-off shaft of a tractor, which is connected via a universal joint shaft to the drive trunnion 19.

The gearbox housing 16 has a bore 20 at the side opposite the drive trunnion 19. The bore 20 is closed by the hydraulic pump arrangement 1. The hydraulic pump arrangement 1 is flanged via attachment screws 17 to the gearbox housing 16. The hydraulic pump arrangement 1 has a pump drive shaft 21 to drive the hydraulic pump 2. The pump drive shaft 21 is passed through the bore 20 into the inside of the gearbox housing 16. The pump drive shaft 21 is, drive-wise, directly connected via a shaft-hub-connection to the drive shaft 18. Thus, the hydraulic pump 2 is directly driven by the drive shaft 18 of the gearbox 15. Thus, it is directly driven by the drive unit driving the gearbox 15.

The gearbox housing 16 has a gearbox bottom 23. The oil sump 13 is formed in the gearbox bottom 23. The oil is accumulated in the oil sump 13. The oil has, within an accommodation chamber 63 (see FIG. 7), an oil level 25 that is indicated by the dotted line.

FIGS. 3 to 6 show the hydraulic pump arrangement 1 and its individual components in detail and are described in the following together.

The hydraulic pump arrangement is structured modularly and has an inlet module 26, a pump module 27 as well as an outlet module 28. The individual modules 26, 27, 28 are connected to each other by locating pins 29, 30 and connecting screws 31, 32.

FIG. 4 shows a cross-sectional view of the pump module 27. In this view, the hydraulic pump 2, in the form of a gear pump has a first gear 35 and a second gear 36. The two gears 35, 36 mesh with each other. The hydraulic pump 2 is formed as a conventional gear pump. Furthermore, the first hydraulic port 3 and the second hydraulic port 4 are formed in the pump module 27.

The first gear 35 is, drive-wise, connected to the pump drive shaft 21. Thus, the first gear 35 represents the driven gear 35. The second gear 36 is driven by the first gear 35 and is supported via a bearing shaft 37. The bearing shaft 37 is held and supported in the inlet module 26 and in the outlet module 28.

FIG. 5 shows a top plan view of the inlet module 26. In the inlet module 26, a first inlet opening 33 is provided. The first inlet opening 33 is aligned with a first bore in the gearbox housing 16 of the gearbox 15 and thus, hydraulically connected to it. The first inlet opening 33 is connected via a connection passage in the form of a first bore 38 to a first outlet opening 39. The first outlet opening 39 is aligned with the first hydraulic port 3 of the pump module 27 and hydraulically connected to it. The first inlet opening 33, the first bore 38 and the first outlet opening 39 form part of the first feed line 5 of FIG. 1. The non-return or check valve 9 of the first feed line 5 is arranged in the first bore of the gearbox housing 16, which also forms part of the first feed line 5.

Furthermore, the inlet module 26 has a second opening 34 that is connected via a connection passage, in form of a second bore 40, to the second outlet opening 41. The second inlet opening is aligned with a second bore of the gearbox housing 16 and thus hydraulically connected to it. The second outlet opening 41 is aligned with the second hydraulic port 4 of the pump module 27 or the hydraulic pump 2 and thus, is hydraulically connected to it. The second inlet opening 34, the second bore 40 and the second outlet opening 41 form part of the second feed line 7 of FIG. 1. The non-return or check valve 11 is arranged in the second bore of the gearbox housing 16, which also forms part of the second feed line 7.

In the inlet module 26 several connection bores 44, 45, 46, 47 are provided, to accommodate the locating pins 29, 30 and the connecting screws 31, 32. Besides these connecting screws, further, not shown, screws are provided. Furthermore, at the inlet module 26, the attachment screws 17 (FIG. 2) can be passed through attachment bores 48, 49. This enables the inlet module 26 to flange to the gearbox housing 16.

A through bore 42 serves to enable passage of the pump drive shaft 21 through the gearbox housing 16. A bearing bore 43 serves to accommodate the bearing shaft 37.

FIG. 6 shows a cross-sectional view through the outlet module 28. The outlet module 28 has a first inlet opening 50 that is hydraulically connected to a connection passage in the form of a first bore 52. The first bore 52 extends from the outside up to the first inlet opening 50. The first inlet opening 50 is aligned with the first hydraulic port 3 of the pump module 27. Furthermore, the non-return or check valve 10 of FIG. 1 is arranged in the first bore 52. The first inlet opening 50 and the first bore 52 form part of the first discharge line 8 of FIG. 1. The outlet module 28 includes a second inlet opening 51 that is hydraulically connected to a connection passage in the form of a second bore 53. The second bore 53 is formed identically and parallel to the first bore 52. The non-return or check valve 10 of FIG. 1 is arranged in the second bore 53. The second inlet opening 51 is aligned with the second hydraulic port 4 of the hydraulic pump 2 in the pump module 27. The second inlet opening 51 and the second bore 53 form part of the second discharge line 8 of FIG. 1.

The two bores 52, 53 are hydraulically connected to a discharge line 54. The discharge line 54 is in the form of a bore extending transversally to the two bores 52, 53. For this, the first bore 52 and the second bore 53 cross the discharge line 54. The openings of the bores 52, 53 are closed at the ends facing away from the inlet openings 50, 51 by dummy plugs 56, 57. The discharge line 54 ends in a discharge opening 55.

The outlet module 28 includes bearing bores 58, 59 to accommodate the pump drive shaft 21 and the bearing shaft 37. A connection bore 60 is shown that threadably receives one of the connecting screws 32.

FIG. 7 shows a cross-sectional view of the gearbox housing 16 in the area of the oil sump 13. Here it is visible, that two inner housing walls 61, 62, starting from the housing bottom 23, extend upwards and form an accommodation chamber 63. The accommodation chamber 63 accommodates the gear 24 of the drive shaft 18. The accommodation chamber 63 is open towards its top to enable a tooth meshing of the gear 24 with a further gear 64 of the gearbox. Between the outer housing walls 65, 66 and the inner housing walls 61, 62, two sump chambers 67, 68 are formed. Oil is accumulated in the two sump chambers 67, 68. The oil levels are indicated by the dotted lines 69, 70. Oil, that flows into the accommodation chamber 63, is catapulted by the gear 24 of the drive shaft 18 upwards, so that it is thrown over the inner housing walls 61, 62. The oil then flows into the sump chambers 67, 68. In this case, for example, different oil levels, which furthermore vary temporarily, can be found in the accommodation chamber 63 and in the sump chambers 67, 68. The sump chambers 67, 68 serve as settling chambers, to prevent a sucking-in of air into the hydraulic pump arrangement. In each of the sump chambers 67, 68, respectively, a bore 72, 73 is visible. The bores 72, 73 are connected to the inlet openings of the hydraulic pump arrangement. The non-return valves 9, 11 of the feed lines 5, 7 are arranged in the bores 72, 73.

To be able to maintain the oil level in both sump chambers 67, 68 at the same height, a connection passage 71 is provided to connect the two sump chambers 67, 68. The connection passage 71 extends transversally to the drive shaft 18 and is visible in FIG. 2.

The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.

Claims

1. A gearbox, comprising:

a hydraulic pump with two flow directions, the hydraulic pump includes a first hydraulic port and a second hydraulic port,

a first feed line and a first discharge line are both connected to the first hydraulic port; and

a second feed and a second discharge are both connected to the second hydraulic port;

a non-return valve is arranged in each feed line and in each discharge line, the feeds are connected to an oil sump of the gearbox;

a gear box drive shaft drives the hydraulic pump, the drive shaft of the gearbox includes at least one gear;

a gearbox housing includes a housing bottom, wherein the oil sump is arranged in the housing bottom;

an accommodation chamber is provided in the housing bottom for accommodating the gear of the drive shaft, the accommodation chamber separates the oil sump into a first sump chamber and into a second sump chamber; and

the first feed line of the hydraulic pump arrangement is connected to the first sump chamber and the second feed line of the hydraulic pump arrangement is connected to the second sump chamber.

2. The gearbox according to claim 1, wherein the non-return valves in the feed lines open in the direction to the respective hydraulic port and the non-return valves in the discharge lines close in the direction to the respective hydraulic port.

3. The gearbox according to claim 1, wherein the first discharge line and the second discharge line are connected to a joint discharge line.

4. The gearbox according to claim 1, wherein the hydraulic pump is a gear pump, a vane pump or a piston pump.

5. The gearbox according to claim 1, wherein the hydraulic pump has a pump housing, that is detachably connected to the gearbox housing.

6. The gearbox according to claim 5, wherein the pump housing has two inlet openings that are connected to bores leading into the sump chambers in the gearbox housing and the non-return valves of the feed lines are arranged in the bores of the gearbox housing.

7. The gearbox according to claim 1, wherein the hydraulic pump further comprises an inlet module, a pump module and an outlet module, the modules are detachably connected to each other, and connection passages are provided in the inlet module as part of the feed lines, the connection passages extend from inlets to the hydraulic pump, the hydraulic pump is provided in the pump module and connection passages are provided in the outlet module as part of the discharge lines, the connection passages extend from the hydraulic pump to a discharge line.

8. The gearbox according to claim 7, wherein a pump drive shaft for driving the hydraulic pump is passed from the pump module through the inlet module.

9. The gearbox according to claim 8, wherein the pump drive shaft is passed through a through bore in the gearbox housing and is, drive-wise, detachably connected within the gearbox housing to the drive shaft.

10. A gearbox, comprising:

a hydraulic pump,

a first feed line and a second feed line both feeding oil to the hydraulic pump, the feed lines are connected to an oil sump of the gearbox,

a gearbox drive shaft drives the hydraulic pump, the drive shaft of the gearbox includes at least one gear,

a gearbox housing has a housing bottom, the oil sump is arranged in the housing bottom,

an accommodation chamber is provided in the housing bottom to accommodate the gear of the drive shaft, the accommodation chamber separates the oil sump into a first sump chamber and a second sump chamber,

the first feed line is connected to the first sump chamber and the second feed line is connected to the second sump chamber.

11. The gearbox according to claim 10, wherein the hydraulic pump has two flow directions and a first hydraulic port and a second hydraulic port,

the first feed line and a first discharge line are both connected to the first hydraulic port and

the second feed line and second discharge line are both connected to the second hydraulic port, and

a non-return valve is arranged in each feed line and in each discharge line.