SHIFTING APPARATUS AND TOWING VEHICLE

Abstract

The disclosure relates to a shifting apparatus for shifting gear stages of a vehicle transmission. The shifting apparatus comprises at least one selector rod which is translationally movable along a shifting direction and the two rod free ends of which are mounted in a manner which can be loaded hydraulically in each case in a pressure chamber for hydraulic medium. The shifting apparatus has a pressure connector and a hydraulic pressure line which is connected to it at each pressure chamber. Moreover, a tank connector and a hydraulic return line which is connected to it are arranged at each pressure chamber. The two return lines open into a common tank line for connection to a hydraulic tank. Moreover, the disclosure relates to a towing vehicle with a shifting apparatus of this type.

Claims

1. A shifting apparatus for shifting gear stages of a vehicle transmission, comprising: at least one selector rod translationally movable along a shifting direction and having the two rod free ends, each of which is mounted in a pressure chamber and can be loaded hydraulically by hydraulic medium in each pressure chamber, a pressure connector and a hydraulic pressure line connected to the pressure connector at each pressure chamber, and a tank connector and a return line connected to the tank connector at each pressure chamber, the two return lines opening into a common tank line for connection to a hydraulic tank.

2. The shifting apparatus of claim 1, comprising a valve unit, which is a shut-off valve, integrated into the common tank line.

3. The shifting apparatus of claim 2, wherein the valve unit is configured as a check valve, the throughflow direction of which is oriented so as to face away from the tank connectors.

4. The shifting apparatus of claim 3, wherein the check valve is loaded with spring force.

5. The shifting apparatus of claim 3, wherein the check valve is configured as a gravity valve.

6. The shifting apparatus of claim 1, wherein an air channel is arranged on at least one of the selector rod and a chamber wall, of the pressure chamber, which is tangent to the selector rod.

7. The shifting apparatus of claim 6, wherein the air channel is arranged in at least one of a highest region of the selector rod and a highest region of the chamber wall.

8. The shifting apparatus of claim 6 wherein the air channel is configured as a recess.

9. The shifting apparatus of claim 6, wherein the air channel is arranged on at least one of a surface of the selector rod and a surface of the chamber wall of the hydraulic chamber.

10. The shifting apparatus of claim 6, wherein the air channel has a triangular cross section.

11. The shifting apparatus of claim 6, wherein the air channel has an arcuate cross section.

12. An agricultural towing vehicle, comprising a shifting apparatus including: at least one selector rod translationally movable along a shifting direction and having the two rod free ends, each of which is mounted in a pressure chamber and can be loaded hydraulically by hydraulic medium in each pressure chamber, a pressure connector and a hydraulic pressure line connected to the pressure connector at each pressure chamber, and a tank connector and a return line connected to the tank connector at each pressure chamber, the two return lines opening into a common tank line for connection to a hydraulic tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The shifting apparatus according to the disclosure will be explained in greater detail in the following text using the appended drawings. Here, components which are corresponding or comparable with regard to their function are identified by the same designations.

[0024] FIG. 1 shows a diagrammatic illustration of an agricultural towing vehicle according to the disclosure.

[0025] FIG. 2 shows a diagrammatic side view of the shifting apparatus according to the disclosure.

[0026] FIG. 3 shows a diagrammatic view of a selector rod of the shifting apparatus according to the arrow direction III in FIG. 2.

[0027] Like reference numerals are used to indicate like elements throughout the several figures.

DETAILED DESCRIPTION

[0028] FIG. 1 shows a diagrammatic illustration of an agricultural towing vehicle 10 according to the disclosure, in particular in the form of a tractor, with a drive train 20 in one possible embodiment. The basic design of an agricultural towing vehicle 10 is assumed to be known to a person skilled in the art. The towing vehicle 10 also comprises a cab 12, a front vehicle axle 14, and a rear vehicle axle 26. The front vehicle axle 14 and the rear vehicle axle 26 are part of the drive train 20, with it being possible for the rear vehicle axle 26 generally to be permanently driven and the front vehicle axle 14 generally to be activatable on demand.

[0029] Furthermore, the drive train 20 comprises a drive engine 22 which can be configured as an internal combustion engine, and a transmission structure which can be assembled from different individual transmission components. The transmission structure can have a transmission arrangement 30 in the power and torque flow, starting from the drive engine 22. The transmission arrangement 30 is drive-connected to the drive engine 22 and/or can be capable of being driven to the drive engine 22.

[0030] Drive power of the drive engine 22 can be transmitted by way of the transmission arrangement 30 with different gear stages to an output shaft. The rear vehicle axle 26, which is drive-connected to the output shaft and converts a rotation of the front and/or the rear vehicle axle (via ground engagement means connected thereto) into propulsion of the tractor, is therefore driven at a different rotational speed depending on a gear stage selected in the transmission arrangement 30. Consequently, a tractor equipped with the transmission arrangement 30 is movable in different speed ranges depending on the gear stage selected in the transmission arrangement 30.

[0031] The towing vehicle 10 can have one or more ground engagement means in the form of wheels 28 which are in engagement with an underlying surface to transmit drive forces and/or by way of which the towing vehicle 10 is supported on the underlying surface. The towing vehicle 10 can, moreover, have a chassis, it being possible for the chassis in particular to be supported by the wheels suspended on the front and the rear vehicle axle 14, 26.

[0032] FIG. 2 shows a shifting apparatus 40 with at least one selector rod 42. All selector rods 42 which are present are preferably combined with the same technical features, as described in the following text on the basis of the single selector rod 42.

[0033] The shifting apparatus 40 can be mounted inside or outside a housing of the transmission arrangement 30. The shifting apparatus 40 is coupled to the transmission arrangement 30 in order to shift different gear stages, for example, in such a way that the hydraulically loaded selector rod 42 displaces a slider sleeve, mounted on a transmission output shaft, axially via a selector fork which is fastened to it.

[0034] The selector rod 42 has two rod free ends 44 which lie axially opposite one another and are each mounted in a pressure chamber 46. The two rod free ends 44 can be loaded by means of hydraulic pressure, in order to bring about a specific or defined movement along an axial direction 48 of the selector rod 42. The axial direction 48 which acts as shifting direction of the selector rod 42 can achieve the shifting of a gear stage or a transfer of the selector rod 42 into a neutral middle position. The neutral middle position is shown in FIG. 2. Starting from this middle position, the selector rod 42 can be moved either to the left or to the right in a manner which is dependent on the hydraulic pressure loading, in order to assume one gear shifting position of two possible gear shifting positions, which brings about the shifting of a gear stage.

[0035] For the pressure loading of the rod free ends 44 by way of a hydraulic medium (for example, oil), each pressure chamber 46 has a pressure connector 50 with a pressure line 52 which is connected to it. For the return of the hydraulic medium to a hydraulic tank (not shown here), the pressure chambers 46 each have a tank connector 54 and a return line 56 which is connected to it. The two return lines 56 open into a tank line 58 which leads to the hydraulic tank and into which a common valve unit 60, for example, a check valve, loaded with spring force, is integrated. A throughflow direction 62 of the valve unit 60 which acts as a shut-off valve is oriented so as to face way from the tank connectors 54.

[0036] FIG. 3 shows a side view of the selector rod 42 along the arrow direction III in FIG. 2. An air channel 64 which runs parallel to the axial direction 48 is arranged on the selector rod 42. Here, the air channel 64 is arranged in a highest region, against gravity, of the selector rod 42 on its outer surface 66, in order to discharge undesired air or gas from the hydraulic chambers 46 as efficiently as possible. The air channel 64 is configured as a recess, for example, a groove, and has a triangular cross section in the exemplary embodiment. In further embodiments (not shown here), an arcuate, in particular semicircular, cross section can be provided, for example.

[0037] As an alternative or in addition to the air channel 64, an air channel (not shown here) which brings about the abovementioned discharge of the air or the gas or assists it in combination with the air channel 64 can be arranged on an inner side of a chamber wall 68 of the respective pressure chamber 46. The chamber wall 68 which has an air channel of this type is tangent to the selector rod 42. The air channel is once again arranged here in a highest region, against gravity, of the chamber wall 68.

[0038] While the above describes example embodiments of the present disclosure, these descriptions should not be viewed in a limiting sense. Rather, other variations and modifications may be made without departing from the scope and spirit of the present disclosure as defined in the appended claims.