Hydraulic system and method for operating a hydraulic system

Abstract

The present invention relates to a hydraulic system (30) comprising: a reversing pump (10) having two delivery connections (23, 24) through which hydraulic medium can be delivered from a tank (20) in opposite delivery directions to hydraulically actuate an actuator (7) and supply hydraulic medium to a cooling and / or lubrication system (1); and a valve assembly (25) through which an actuating piston (11) in a double-acting actuated cylinder (12) can be supplied with hydraulic medium, the actuating piston (11) being mechanically coupled to a locking device (26) and an actuator (7). To reduce the cost of manufacturing the hydraulic system (30), the first delivery connector (23) of the reversing pump (10) is connected to the first tank check valve (17) blocking in the direction of the tank (20) and the first pressure connector (27) of the double-acting drive cylinder (12). The second delivery connector (24) of the reversing pump (10) is connected to the second tank check valve (18) blocking in the direction of the tank (20) and the second pressure connector (28) of the double-acting actuation cylinder (12). The actuation piston (11) is mechanically connected to the valve piston (3) of the valve (15), and the valve piston (3) is mechanically connected to the actuation element (7).

Description

Technical Field

[0001] This invention relates to a hydraulic system comprising: a reversing pump having two delivery connections through which hydraulic medium can be delivered from a tank in opposite delivery directions to hydraulically actuate an actuating element and supply hydraulic medium to a cooling and / or lubrication system; and a valve assembly through which an actuating piston in a double-acting actuated cylinder can be supplied with hydraulic medium, wherein the actuating piston is mechanically coupled to a locking device and an actuating element. The invention also relates to a method for operating such a hydraulic system. Background Technology

[0002] A hydraulic device with a pump is known from German patent application DE 10 2018 112 670 A1. This device can be connected to a coolant line for supplying hydraulic medium to a first consumer for cooling and / or lubrication of the first consumer, and the device can be connected to an actuation line for supplying a second consumer, and the device can be connected to the same hydraulic device for actuation thereon. The pump is designed as a reversing pump. A hydraulic parking lock actuator with a double-acting piston is supplied with hydraulic fluid for actuating the parking lock. The piston is designed as a differential area piston. The parking lock actuator can be fixed in place via a locking device having a sized, pre-tensioned blocking element arranged to engage in a recess of opposite shape. Summary of the Invention

[0003] The object of this invention is to reduce the cost of manufacturing a hydraulic system comprising: a reversing pump having two delivery connections through which hydraulic medium can be delivered from a tank in opposite delivery directions to hydraulically actuate an actuator and supply hydraulic medium to a cooling and / or lubrication system; and a valve assembly through which an actuating piston in a double-acting actuated cylinder is supplied with hydraulic medium, wherein the actuating piston is mechanically coupled to a locking device and an actuating element.

[0004] This objective is achieved by a hydraulic system comprising: a reversing pump having two delivery connections through which hydraulic medium can be delivered from a tank in opposite delivery directions to hydraulically actuate an actuator and supply hydraulic medium to a cooling / or lubrication system; and a valve assembly through which an actuating piston in a double-acting actuated cylinder can be supplied with hydraulic medium, wherein the actuating piston is mechanically coupled to a locking device and an actuating element. The system is characterized in that a first delivery connection of the reversing pump is connected to a first tank check valve blocking in the direction of the tank and a first pressure connection of the double-acting actuated cylinder; a second delivery connection of the reversing pump is connected to a second tank check valve blocking in the direction of the tank and a second pressure connection of the double-acting actuated cylinder; and the actuating piston is mechanically coupled to a valve piston, which in turn is mechanically coupled to the actuating element. The actuating element is, for example, used to actuate a parking lock, a claw clutch, etc. Compared to conventional hydraulic systems, an active valve is not required.

[0005] A preferred exemplary embodiment of the hydraulic system is characterized in that the valve has two inlets, which are connected to the delivery connection of the directional pump via a cooling check valve that blocks the inlets. Depending on the pumping direction, the directional pump can move the valve piston in one direction or the other to actuate the actuating element in one direction or the other.

[0006] Another preferred exemplary embodiment of the hydraulic system is characterized in that the valve has two outlets connected to a cooling and / or lubrication system. The cooling and / or lubrication system can be adequately supplied with hydraulic medium via both outlets. Advantageously, only one of the two outlets is open for cooling and / or lubrication. Furthermore, the valve's inlet and outlet are advantageously arranged such that supplying hydraulic medium to the cooling and / or lubrication system does not result in pressure loss or significant pressure loss within the hydraulic system.

[0007] Another preferred exemplary embodiment of the hydraulic system is characterized in that a valve piston in the valve defines two external valve chambers that are hydraulically connected to each other. In this way, pressure balance between the two external valve chambers can be achieved in a simple manner. The hydraulic connection can be implemented internally, for example, where the hydraulic connection extends through the valve piston itself. However, the hydraulic connection can also be implemented via an external connection line on the valve.

[0008] Another preferred exemplary embodiment of the hydraulic system is characterized in that a valve piston in the valve defines an inner valve chamber arranged axially between outer valve chambers. The term axial refers to the axis of motion of the valve piston. Axial means the direction along or parallel to the axis of motion of the valve piston. The two inlets of the valve are advantageously arranged in the center or middle of the valve. The two inlets are advantageously axially spaced apart from each other.

[0009] Another preferred exemplary embodiment of the hydraulic system is characterized in that the valve piston is mechanically coupled to a locking cam, which includes two cam ramps that interact with a locking element of the locking device preloaded by a spring mechanism. Movement of the valve piston is initiated by a reversing pump via an actuating piston. Once the valve piston reaches one of its two end positions, the locking device influences the movement of the valve piston via the interaction of the cam ramps with the locking element of the locking device.

[0010] Another preferred embodiment of the hydraulic system is characterized by a cam ramp located at the end of the platform. As long as the locking element is in contact with the platform of the locking cam, the locking device has little or no effect on the movement of the valve piston. The cam ramp slopes downwards at the opposite end of the platform. Depending on the direction of movement, kinetic energy, along with the preload force of the spring device, is either stored in or released by the spring device.

[0011] The present invention also relates to valves, particularly valve pistons, locking devices, particularly locking elements or locking cams, actuating pistons, actuating cylinders, directional pumps, and / or check valves for use in hydraulic systems as described above. The mentioned components may be sold separately.

[0012] In a method for operating a hydraulic system as described above, the aforementioned objective is achieved alternatively or additionally by means of an actuating element actuated by a reversing pump via an actuating piston and a valve piston in a first or second direction, wherein the actuating piston, at a corresponding end position, unblocks only one of the valve outlets. In this way, sufficient, but not excessive, hydraulic medium is delivered to the cooling and / or lubrication system in a simple manner.

[0013] A preferred exemplary embodiment of the method is characterized in that the locking element moves via one of the cam ramps at the start of actuation to store kinetic energy in a preloaded spring device, which is released again via the locking element at the end of actuation. This ensures that the valve piston or actuating piston safely reaches its end position even when hydraulic displacement is no longer possible due to an open outlet on the valve for cooling and / or lubrication. Attached Figure Description

[0014] Other advantages, features and details of the present invention will be readily understood from the following description, in which various exemplary embodiments are described in detail with reference to the accompanying drawings.

[0015] The only accompanying drawing shows a hydraulic system with a reversing pump, a valve assembly, and a double-acting actuated cylinder, which includes an actuating piston mechanically connected to a valve piston, which in turn is mechanically connected to a locking device and an actuating element. Detailed Implementation

[0016] exist Figure 1 The diagram illustrates a hydraulic system 30 with a reversing pump 10. The reversing pump 10 can deliver hydraulic medium from tank 20 and through suction filter 19 in opposite directions, as indicated by the arrow symbol in the pump symbol of the reversing pump 10. The reversing pump 10 is driven by a pump motor 16. The pump motor 16 is, for example, an electric motor.

[0017] Figure 1 The first delivery connector 23 is shown on the left side of the reversing pump 10. Figure 1 The second delivery connector 24 is shown on the right side of the reversing pump 10. The first delivery connector 23 can be connected to tank 20 via the first tank check valve 17. The second delivery connector 24 can be connected to tank 20 via the second tank check valve 18.

[0018] The two check valves 17 and 18 block the flow in the direction of tank 20. Figure 1 In this configuration, an actuating cylinder 12 is arranged above the pump motor 16 of the reversing pump 10. The actuating cylinder 12 is designed as a double-acting cylinder with an actuating piston 11.

[0019] The actuating piston 11 divides the actuating cylinder 12 into pressure chambers 13 and 14. One pressure chamber 14 is connected to the first delivery connection 23 of the reversing pump 10 via a first pressure connection 27. The other pressure chamber 13 is connected to the second delivery connection 24 of the reversing pump 10 via a second pressure connection 28.

[0020] In addition to tank check valves 17 and 18, valve assembly 25 also includes a first cooling check valve 8 and a second cooling check valve 9. The first cooling check valve 8 is connected between the first delivery connection 23 of the reversing pump 10 and the first inlet 31 of the valve 15. The second cooling check valve 9 is connected between the second delivery connection 24 of the reversing pump 10 and the second inlet 32 ​​of the valve 15. Figure 1 In the middle, inlets 31 and 32 are located at the bottom of valve 15.

[0021] exist Figure 1 The valve 15 at the top has two outlets 33 and 34. The outlets 33 and 34 of the valve 15 are connected to the cooling and / or lubrication system 1.

[0022] exist Figure 1 In valve 15, valve piston 3 is guided back and forth to the left and right. Valve piston 3 of valve 15 is mechanically connected to actuating piston 11 of double-acting actuated cylinder 12. This mechanical connection is made, for example, by means of a piston rod, which is not described in more detail. Valve piston 3 is mechanically connected to actuating element 7 and locking device 26 via another piston rod, which is not described in more detail.

[0023] The valve piston 3 includes two valve piston bodies, and the interior of the valve 15 is divided into two outer valve chambers 35 and 36 and an inner valve chamber 37 via the two valve piston bodies.

[0024] Two inlets 31 and 32 are axially positioned at the center of the bottom of valve 15. The two inlets 31 and 32 are axially spaced apart from each other. Figure 1 In the middle, the two outlets 33 and 34 are arranged at the top of the valve 15 to face outwards more than the inlets 31 and 32, that is, laterally offset to the left and right relative to the inlets.

[0025] The two outer valve chambers 35 and 36 of valve 15 are connected to each other via connecting line 2. Connecting line 2 extends through valve piston 3. The dashed line above valve 15 indicates that the outer valve chambers 35 and 36 can also be connected to each other via an external connecting line.

[0026] exist Figure 1 In the middle, the valve piston 3 is in the same position as the actuating piston 11. Figure 1 In the left end position of the valve piston 3, the inlet 32 ​​of the valve 15 is connected to the outlet 33 via the inner valve chamber 37. Therefore, the cooling and / or lubrication system 1 is supplied with hydraulic medium via the inlet 32 ​​and outlet 33 of the valve 15.

[0027] Inlet 31 is closed by valve piston 3. Outer valve chamber 35 is also connected to cooling and / or lubrication system 1 via outlet 34, but no hydraulic medium flows through outlet 34 when valve piston 3 is in the illustrated end position.

[0028] The locking device 26 includes a cam ramp 21 mechanically coupled to the valve piston 3. Figure 1 In this configuration, the cam ramp 21 includes a platform located on its upper side, and the two cam ramps 21 and 22 extend from the ends of the platform. Figure 1 In the middle, cam ramps 21 and 22 tilt downwards from the platform to the left and right, respectively. Locking cam 6 interacts with locking element 5. Figure 1 In the middle, the locking element 5 is designed as a ball and is preloaded downward against the locking cam 6 by the spring device 4.

[0029] exist Figure 1 In the state shown in the hydraulic system 30, the locking element 5 rests against the locking cam 6. Figure 1 On the right side of the cam ramp 22. If the reversing pump 10 switches to Figure 1 The state shown causes the reversing pump to deliver to the right, that is, from the delivery connector 23 to the delivery connector 24, so the hydraulic medium is delivered via... Figure 1 The check valve 17 on the left side of the tank draws water from tank 20. Simultaneously, hydraulic fluid flows through... Figure 1 The lower cooling check valve 9 in the middle is supplied to valve 15 via inlet 32.

[0030] Due to the position of the valve piston, only outlet 33 is open in valve 15, so the hydraulic medium used for cooling and / or lubrication 1 is delivered via this outlet. The pressurized right-side pressure chamber 13 of the actuating cylinder 12 holds the actuating piston 11 and the valve piston 3 in place. Figure 1 The left stop position or end position shown is shown.

[0031] If the reversing pump 10 is switched so that it directs... Figure 1 The left-side conveying, i.e., conveying from conveying connector 24 to conveying connector 23, then the hydraulic medium passes through... Figure 1 The check valve 18 on the right side of the tank draws out the contents of the tank 20 and is conveyed to the actuator cylinder 12. Figure 1 In the pressure chamber 14 on the left side of the cylinder 12. Since the right inlet 31 of the valve 15 is closed by the valve piston 3, hydraulic pressure can be established in the pressure chamber 14 of the actuator cylinder 12, and the actuator piston 11 moves to the right by this hydraulic pressure.

[0032] Due to the mechanical connection between the actuating piston 11 and the valve piston 3, the valve piston 3 also moves to the right and first closes the outlet 33 for cooling and / or lubrication 1 before the valve piston 3 releases the inlet 31 of the valve 15, as... Figure 1 As illustrated on the right side of the diagram. Therefore, throughout the actuation process, the actuation pressure in pressure chamber 14 for displacing the actuating piston 11 is maintained, causing the actuating piston 11 to move almost to the desired position. Figure 1 The stop position on the right side of the middle.

[0033] At the start of actuation, locking element 5 is displaced by locking cam 6, which is shifted via actuation element 7, against the force of spring device 4, which is loaded with mechanical energy. Near the end of the actuation process, valve piston 3 first closes. Figure 1 The valve inlet 32 ​​on the left side and then Figure 1 The valve outlet 34 on the right side is released. Because this causes a drop in the hydraulic pressure used to further displace the actuating piston 11 until it reaches the stop position, the actuating piston 11 can no longer be hydraulically displaced.

[0034] However, in this state, the locking element 5, which has already been subjected to the preload of the spring device 4, is already in the position... Figure 1 On the left-hand descending cam ramp 21, the switching element or actuating element 7, along with the pistons 3 and 11 connected to it, can move further to the right via the descending cam ramp using the energy stored in the spring device 4. The reverse switching actuation of the actuating element 7 is performed in a similar manner.

[0035] List of reference numerals

[0036] 1. Cooling and / or lubrication system

[0037] 2 Connecting pipelines

[0038] 3. Valve piston

[0039] 4. Spring device

[0040] 5 Locking elements

[0041] 6. Locking Cam

[0042] 7 Actuating elements

[0043] 8 First cooling check valve

[0044] 9 Second Cooling Check Valve

[0045] 10 Reversing Pump

[0046] 11 Actuating Piston

[0047] 12 Actuating Cylinders

[0048] 13 Pressure Chambers

[0049] 14 Pressure Chamber

[0050] 15 valves

[0051] 16 Pump Motor

[0052] 17 First tank check valve

[0053] 18 Second tank check valve

[0054] 19 Suction Filter

[0055] 20 cans

[0056] 21 Cam ramp

[0057] 22 Cam ramp

[0058] 23 First conveying connector

[0059] 24 Second conveying connector

[0060] 25 Valve Assembly

[0061] 26 Locking device

[0062] 27 First pressure connection

[0063] 28 Second pressure connection

[0064] 30 Hydraulic System

[0065] Entrance 31

[0066] 32 entrances

[0067] 33 Exports

[0068] 34 Exports

[0069] 35 External valve chamber

[0070] 36 External valve chamber

[0071] 37. Internal valve chamber

Claims

1. A hydraulic system (30), the hydraulic system comprising: A reversing pump (10) having two delivery connections (23, 24) through which hydraulic medium can be delivered from the tank (20) in opposite delivery directions to hydraulically actuate the actuator (7) and supply hydraulic medium to the cooling and / or lubrication system (1); and a valve assembly (25) through which the actuating piston (11) in the double-acting actuating cylinder (12) can be supplied with hydraulic medium, wherein the actuating piston (11) is mechanically coupled to the locking device (26) and the actuator (7), characterized in that the first delivery connection of the reversing pump (10) is connected to the tank (20) The first tank check valve (17) and the first pressure connection (27) of the double-acting actuating cylinder (12) are blocked in the direction of the tank (20), wherein the second delivery connection of the reversing pump (10) is connected to the second tank check valve (18) and the second pressure connection (28) of the double-acting actuating cylinder (12) which are blocked in the direction of the tank (20), wherein the actuating piston (11) is mechanically connected to the valve piston (3) of the valve (15) and the valve piston (3) is mechanically connected to the actuating element (7); the valve piston (3) in the valve (15) defines two outer valve chambers (35, 36) that are hydraulically connected to each other.

2. The hydraulic system according to claim 1, characterized in that, The valve (15) has two inlets (31, 32), which are connected to the delivery connector (23, 24) of the reversing pump (10) via cooling check valves (8, 9) that block the inlets (31, 32).

3. The hydraulic system according to claim 2, characterized in that, The valve (15) has two outlets (33, 34) connected to the cooling and / or lubrication system (1).

4. The hydraulic system according to claim 1, characterized in that, The valve piston (3) in the valve (15) defines the inner valve chamber (37) which is arranged axially between the outer valve chambers (35, 36).

5. The hydraulic system according to claim 3, characterized in that, The valve piston (3) is mechanically connected to the locking cam (6), which includes two cam ramps (21, 22) that interact with the locking element (5) of the locking device (26) preloaded by the spring device (4).

6. The hydraulic system according to claim 5, characterized in that, The cam ramps (21, 22) are located at the ends of the platform.

7. A method for operating a hydraulic system (30) according to claim 5 or 6, characterized in that, The actuating element (7) is actuated by the reversing pump (10) in a first or second direction via the actuating piston (11) and the valve piston (3), wherein the actuating piston (11) releases obstruction of only one of the outlets (33, 34) of the valve (15) at a corresponding end position.

8. The method according to claim 7, characterized in that, The locking element (5) moves via one of the cam ramps (21, 22) at the start of actuation to store kinetic energy in a preloaded spring device (4), which is released again via the locking element (5) at the end of actuation.

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