Hydromotor

Abstract

A hydraulic motor is revealed whose displacement volume can be adjusted via control fluid supplied through an external control pressure port. A flow of coolant is diverted from this control fluid. A baffle is provided downstream of this diversion, allowing the diverted coolant flow to be set or adjusted before it absorbs heat from the hydraulic motor. The coolant, along with any leakage (which also serves as coolant), is collected in a lower section of the housing and discharged via a reservoir port. The hydraulic motor can be an axial piston motor with two adjustable displacement volumes.

Description

[0001] The invention relates to an adjustable hydraulic motor according to the preamble of claim 1.

[0002] German patent application DE 41 29 667 A1 discloses an adjustable hydraulic motor integrated into a hydrostatic transmission with an open circuit. Such hydraulic motors generate waste heat, or heat loss, depending on their efficiency. This heat loss depends on the operating conditions, such as the set displacement volume, the rotational speed, and the pressure conditions within the hydraulic motor. The surface area of ​​the hydraulic motor housing and the flow rate exiting the low-pressure side of the hydraulic motor are primarily responsible for dissipating this heat loss.

[0003] Beyond the aforementioned heat dissipation methods, waste heat is often dissipated via leakage from the engine (e.g., from the cylinder-piston units) of the hydraulic motor. This leakage is then collected in the housing and drained from the hydraulic motor.

[0004] Furthermore, it is known from the prior art to dissipate waste heat from the hydraulic motor via an additional purge flow. This flow is drawn from the working fluid on the low-pressure side via a valve or orifice. After the purge flow has absorbed (as much as possible) waste heat, it is combined in the housing and from there – along with the leakage – discharged from the hydraulic motor (e.g., to an external tank).

[0005] A disadvantage of such hydraulic motors is that the flushing fluid flow taken from the low-pressure side is missing from the circuit, which can lead to insufficient supply. Another disadvantage is that the hydraulic fluid taken from the low-pressure side already has a certain temperature and therefore can no longer cool optimally.

[0006] In contrast, the invention is based on the objective of creating an adjustable hydraulic motor that avoids both of the aforementioned disadvantages.

[0007] This problem is solved by a hydraulic motor with the features of claim 1.

[0008] The claimed hydraulic motor has a housing and an adjustment device for adjusting the displacement volume, which can be supplied with control fluid from an external control fluid source. According to the invention, the hydraulic motor has a device for diverting control fluid, which then serves as a coolant for absorbing and dissipating waste heat from the hydraulic motor. For this purpose, the coolant is preferably directed more or less selectively inside the housing to locations or areas where the waste heat is generated and from which it needs to be dissipated. At these locations or areas, for example, relative mechanical movements of components of the hydraulic motor occur. Alternatively, the coolant can also absorb waste heat through untargeted contact with the housing, particularly if the housing is made of metal and can thus conduct the waste heat well. This results in a hydraulic motor with a flushing or...A cooling system has been designed that cannot lead to an insufficient supply to the circuit to which the hydraulic motor is connected. Furthermore, the flushing / cooling system has a comparatively high cooling capacity because the control fluid is not preheated.

[0009] The cooling capacity can be easily increased by increasing the control fluid flow rate, which also increases the coolant flow rate.

[0010] In a preferred embodiment, the heated coolant is collected in a lower area of ​​the housing and discharged from the housing via a tank connection. Leakage can also be collected in this area, further enhancing the overall cooling of the hydraulic motor according to the invention.

[0011] If the housing has a control pressure port that is connected to the adjusting device via a control pressure channel, then the device preferably has a cooling channel that is connected to this control pressure channel.

[0012] In a preferred further development, a throttle is arranged in the cooling channel, via which the coolant volume flow can be determined or controlled.

[0013] The throttle can have different sizes, so that the coolant flow rate can be adjusted even after the production of the hydraulic motor according to the invention.

[0014] If the adjusting device has an actuating cylinder (e.g., a differential cylinder) that has an actuating pressure chamber (e.g., a piston crown chamber) acting in the direction of a reduction in displacement volume, and which can be supplied with actuating fluid via a first position of a valve body, then it is particularly preferred if the valve body can be moved into this first position by increasing the control pressure in the control pressure channel. Thus, when the control pressure is increased, the displacement volume is reduced, or, with a constant flow of working fluid into the hydraulic motor, its output speed is increased. Any additional heating of the hydraulic motor associated with this can be eliminated by the additional coolant flow rate resulting from the increase in control pressure.

[0015] In a preferred embodiment of the adjusting device, the valve is a 3 / 2-way valve, the valve body of which is acted upon by a spring in the direction of a second position, through which the actuating pressure medium can be released from the actuating pressure chamber.

[0016] In a preferred application of the flushing or cooling device according to the invention, the valve or the 3 / 2-way valve is a switching valve, so that the hydraulic motor is a two-point motor in which two different flow volumes can be set. The valve body can then be switched to the first position by increasing the control pressure in the control pressure channel.

[0017] Then the valve body can be switched to the second position by reducing the control pressure in the control pressure channel.

[0018] An embodiment of the invention is described in detail below with reference to the figure. The figure shows a circuit diagram of the embodiment of the hydraulic motor according to the invention.

[0019] According to this embodiment, the hydraulic motor is an axial piston motor equipped as a switching motor with a hydraulic two-point adjustment. It has a drive unit 1, which comprises a (not shown) cylinder drum with cylinder-piston units distributed around its circumference. The pistons are coupled to a (not shown) swashplate via piston feet or piston shoes, or, in the case of a swashplate, to a control lens via the cylinder drum, the pivot angle of which can be adjusted by means of an actuating cylinder 2 designed as a differential cylinder.

[0020] An annular space 4 of the actuating cylinder 2, which in the illustrated embodiment is maximally filled, acts in the direction of the larger swivel angle and thus the larger displacement volume of the cylinder-piston units. A piston crown space 6 of the actuating cylinder 2 acts in the opposite direction in the direction of the smaller swivel angle and thus the smaller displacement volume of the cylinder-piston units and thus of the engine 1.

[0021] An output shaft 8 protrudes from a housing 10 and rotates through the two working channels 12, 14 depending on the set swivel angle and depending on the direction and flow rate. The first working channel 12 is connected to a first working port A, while the second working channel 14 is connected to a second working port B. Since the hydraulic motor can be operated bidirectionally, or rather its output shaft 8 can be driven bidirectionally, high pressure can be applied to either working port A or working port B, so that the first working line 12 or the second working line 14 carries high pressure. Accordingly, a pressure relief valve 16, 18 is provided for each of the two working channels 12, 14, through which the respective working channel 12, 14 can be relieved of pressure to the other working channel 14, 12.

[0022] Furthermore, the hydraulic motor has a brake valve 20, which is designed as a continuously adjustable 4 / 3-way valve. The brake valve 20 is simultaneously installed in the first working channel 12 and in the second working channel 14. One valve body of the brake valve 20 is shown in the figure in its central position, which causes maximum throttling of the working channel 12, 14 serving as the return channel, while the hydraulic fluid can flow unrestricted on the inlet side in the other working channel 12, 14 via a respective check valve 22, 24. Due to the bidirectional design of the hydraulic motor, in addition to the central position of the brake valve 20 shown, two more or less restricted through-flow positions of the valve body are possible.In the case of forward torques on the output shaft 8, the valve body of the brake valve 20 is set into the through position assigned to the operating direction of the hydraulic motor, so that the pressure medium of the respective working channel 12, 14 serving as return is throttled.

[0023] The adjustment mechanism of the hydraulic motor has a segment 26 attached to the housing 10, on which two control pressure ports X, X1 and one actuating pressure port G are provided. Inside the segment 26 is a 3 / 2-way valve 28, which controls the filling or emptying of the piston chamber 6 of the actuating cylinder 2 with actuating fluid. For this purpose, the piston chamber 6 is connected to the 3 / 2-way valve 28 via an actuating pressure channel 30. In the position of one valve body of the 3 / 2-way valve 28 shown in the figure, actuating fluid is released from the piston chamber 6, so that the actuating cylinder reaches its position Vg shown in the figure.max assumes a position corresponding to the higher displacement volume of the engine 1. For this purpose, the actuating pressure channel 30 is relieved to a housing interior 32 via the 3 / 2-way valve 28. To switch the engine 1 to the swivel angle with the lower displacement volume, the valve body of the 3 / 2-way valve 28 is moved from the position shown in the figure by means of a control pressure increase to one of the control pressure ports X, X1 and via a control pressure channel 34, so that the actuating pressure port G is connected via the actuating pressure channel 30. This moves the actuating cylinder 2 into its position corresponding to Vg. min designated position.

[0024] A branch 36 is provided on the control pressure channel 34, to which a cooling channel 38 is connected, in which a throttle 40 is provided. Downstream of the throttle 40, the cooling channel 38 opens onto one or more areas 42 of the hydraulic motor to be cooled, e.g., its drive unit 1. Thus, control pressure fluid is diverted at the branch 36 and used as coolant for the hydraulic motor. After absorbing heat, the coolant collects in a region of the housing interior 32, from where it can be drained from the housing 10 via a tank connection T.

[0025] A hydraulic motor is revealed whose displacement volume can be adjusted via control fluid supplied through an external control pressure port. A flow of coolant is diverted from this control fluid. A baffle is provided downstream of this diversion, allowing the diverted coolant flow to be set or adjusted before it absorbs heat from the hydraulic motor. The coolant, along with any leakage (which also serves as coolant), is collected in a lower section of the housing and discharged via a reservoir port. The hydraulic motor can be an axial piston motor with two adjustable displacement volumes. Reference symbol list 1 engine 2 actuator cylinders 4 annular space 6 Actuating pressure chamber, piston crown chamber 8 Output shaft 10 cases 12 first working channel 14 second working channel 16 first pressure relief valve 18 second pressure relief valve 20 brake valve 22 first check valve 24 second check valve 26 segments 28 3 / 2-way valve 30 Control pressure channel 32 Housing interior 34 Control pressure channel 36 Junction 38 Cooling channel 40 Throttle 42 Area to be cooled A first work connection B second work connection X, X1 Control pressure connection G Pressure connection Vg max , Vg min position T tank connection

Claims

Hydraulic motor with a housing (10) and with an adjusting device for adjusting the swallowing volume, which can be supplied with control pressure medium, characterized by a device (36, 38) for discharging control pressure medium as coolant. Hydraulic motor according to claim 1 characterized in that the coolant can be discharged through a tank connection (T) of the housing (10). Hydraulic motor according to claim 1 or 2, wherein the housing (10) has a control pressure port (X, X1) which is connected to the adjusting device via a control pressure channel (34), characterized in that the device has a cooling channel (38) which is connected to the control pressure channel (34). Hydraulic motor according to claim 3, characterized in that a throttle (40) is arranged in the cooling channel (38). Hydraulic motor according to claim 4, characterized in that the throttle (40) is adjustable. Hydraulic motor according to one of claims 3 to 5, wherein the adjusting device has an actuating cylinder (2) which has an actuating pressure chamber (6) acting in the direction of a reduction of the swallowing volume, which can be supplied with actuating pressure medium via a first position of a valve body of a valve, characterized in that the valve body can be brought into the first position by an increase of the control pressure in the control pressure channel (34). Hydraulic motor according to claim 6, wherein the valve is a 3 / 2-way valve (28) whose valve body is acted upon by a spring in the direction of a second position, through which the actuating pressure medium can be released from the actuating pressure chamber (6). Hydraulic motor according to claim 6 or 7, which is a two-point motor, wherein the valve is a switching valve, characterized in that the valve body can be switched into the first position by increasing the control pressure in the control pressure channel (34). Hydraulic motor according to claim 8, which refers back to claim 7, wherein the valve body can be switched into the second position by reducing the control pressure in the control pressure channel (34).

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