JP2020090942A5 - - Google Patents

Description

Hydraulic drive device

The present invention relates to a hydraulic drive that can be used in construction machinery, industrial machinery or agricultural machinery.

A hydraulic motor is generally used as a drive source for work machines mounted on construction machines or industrial machines.

For example, in Patent Document 1, a variable displacement hydraulic motor is used as a drive source for a backhoe swivel. The swash plate is tilted by a hydraulic tilting mechanism. The tilting mechanism includes a piston connected to a swash plate and a regulator that controls the hydraulic pressure that operates the piston. The high pressure side of the inlet / outlet pressure is supplied to the rotating portion that slides and rotates with respect to the swash plate, and is also distributed to the regulator as the primary pressure.

Japanese Unexamined Patent Publication No. 2008-82127

By the way, the hydraulic motor is required to have "holding performance" or "slip performance". Slip means that when torque is applied from the outside while the inlet / outlet port is closed, the liquid leaking portion inside the motor serves as an outlet to rotate the rotating portion. When this rotation is small, the holding performance is said to be high.

When the high pressure side of the inlet / outlet pressure is guided to the regulator and the piston as in the conventional case, if torque is applied from the outside when the outlet side port is closed, liquid leakage from the regulator and the piston is caused. Liquid leakage inside the motor increases, leading to deterioration of holding performance.

Therefore, an object of the present invention is to provide a hydraulic drive device that suppresses deterioration of holding performance.

The hydraulic drive device according to one embodiment of the present invention includes a casing having a pair of inlet / outlet ports, a variable displacement hydraulic motor including a swash plate, and a pair of connecting the pair of inlet / outlet ports to the hydraulic motor. The main line, a hydraulic tilting mechanism that tilts the swash plate, a high-pressure selection valve that selects and outputs the higher pressure of the pair of main lines, and the high-pressure selection valve tilts. A tilt control line connected to the rolling mechanism and an opening / closing mechanism for opening and closing the tilt control line based on a predetermined condition are provided.

According to the above configuration, when the tilt control line is closed, the main line is cut off from the tilt mechanism, so that liquid leakage from the main line can be prevented. Therefore, deterioration of slip performance can be suppressed.

A supply line that merges with the tilt control line and supplies the pressure liquid to the tilt mechanism may be further provided.

According to the above configuration, even in a situation where the tilt control line is closed by the opening / closing mechanism and the tilting mechanism cannot be operated by the hydraulic pressure flowing through the main line, the tilting mechanism is tilted by the pressure liquid from the supply line. The rolling mechanism can be activated. Even if the tilt control line is closed by the opening / closing mechanism, the capacity control of the motor can be continuously executed.

The on-off mechanism may be an electromagnetic on-off valve or a pilot-type on-off valve.

According to the above configuration, it is sufficient to supply / stop the electric signal or the signal pressure depending on the success or failure of the condition, and it is easy to realize the above-mentioned action.

The tilting mechanism includes a piston connected to the swash plate and a regulator for controlling the supply and discharge of pressure liquid to the piston, and supplies the regulator when the opening / closing mechanism is a pilot type on / off valve. The command pressure to be applied may be supplied to the pilot type on-off valve as a signal pressure.

According to the above configuration, the signal pressure supply source and supply path for the opening / closing mechanism can be simplified.

The supply line supplies a higher pressure than the inlet / outlet port, and the opening / closing mechanism is provided on the tilt control line to prevent backflow from the tilt mechanism to the main line, and the check valve. A switching mechanism for switching whether or not the high-pressure pressure liquid can be supplied via the supply line may be provided according to the success or failure of the predetermined conditions.

According to the above configuration, the check valve closes when the switching mechanism is in a state of supplying a high-pressure pressure liquid. It is possible to separate the main line from the tilting mechanism and to keep the tilting mechanism operating in this state.

According to the present invention, it is possible to provide a hydraulic drive device that suppresses deterioration of holding performance.

It is a circuit diagram which shows the hydraulic pressure drive device which concerns on 1st Embodiment. It is a circuit diagram which shows the hydraulic pressure drive device which concerns on 2nd Embodiment. It is a circuit diagram which shows the hydraulic pressure drive device which concerns on 3rd Embodiment. It is a circuit diagram which shows the hydraulic pressure drive device which concerns on 4th Embodiment. It is a circuit diagram which shows the hydraulic pressure drive device which concerns on 5th Embodiment. It is a circuit diagram which shows the hydraulic pressure drive device which concerns on 6th Embodiment.

Hereinafter, embodiments will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a circuit diagram showing a hydraulic pressure drive device 10 according to the first embodiment. The hydraulic drive device 10 according to the embodiment is mounted on a construction machine, an industrial machine, or an agricultural machine (hereinafter, simply collectively referred to as a machine). The machine is provided with a hydraulic drive unit 1 that drives a working machine such as a swivel table. The hydraulic pressure drive unit 1 includes a hydraulic pressure circuit 2 that drives a working machine in a hydraulic pressure manner, and a control device 9 that controls the operation of the hydraulic pressure circuit 2. The hydraulic pressure drive device 10 is an element constituting the hydraulic pressure circuit 2, and serves as an actuator for driving the working machine. The output shaft 10a of the hydraulic drive device 10 is connected to the working machine so as to be able to transmit power.

In addition to the hydraulic pressure drive device 10, the hydraulic pressure circuit 2 includes a pump 3 that supplies hydraulic pressure to the hydraulic pressure drive device 10, a tank 4 that stores hydraulic fluid, and a hydraulic fluid from the pump 3 to the hydraulic pressure drive device 10. A control valve 5 for controlling supply and discharge is provided.

The hydraulic drive device 10 includes a variable displacement hydraulic motor 13 and a casing 11 for accommodating the hydraulic motor 13. The hydraulic motor 13 includes a swash plate 12. The hydraulic motor 13 is a rotary portion that rotates while sliding with respect to the swash plate 12. Although the detailed structure is not shown, the hydraulic motor 13 includes a cylinder block rotatably supported by the casing 11, a plurality of pistons rotatably inserted into the cylinder block, and a swash plate attached to the tip of each piston. Includes a shoe that slides on the twelve. The output shaft 10a of the hydraulic motor 13 rotates integrally with the cylinder block. The tilt angle of the swash plate 12 is variable, and the capacity of the hydraulic motor 13 is changed according to the tilt angle.

The casing 11 has a pair of entrance / exit ports 14, 15. The casing 11 is provided with a pair of main lines 16 and 17 for connecting the pair of inlet / outlet ports 14 and 15 to the hydraulic motor 13. Hereinafter, one port 14 may be referred to as a “first entrance / exit port 14”, and the other port 15 may be referred to as a “second entrance / exit port 15”. The main line 16 connected to the first entrance / exit port 14 may be referred to as a “first main line 16”, and the main line 17 connected to the second entrance / exit port 15 may be referred to as a “second main line 17”.

The hydraulic motor 13 can rotate in both directions. The control valve 5 of the hydraulic circuit 2 rotates the hydraulic motor 13 in the first drive state (right function in FIG. 1) for rotating the hydraulic motor 13 in the first direction, and rotates the hydraulic motor 13 in the second direction opposite to the first direction. It is configured to switch between a second drive state (left function in FIG. 1) and a stop state in which the hydraulic motor 13 is stopped (center function in FIG. 1). The state is switched according to the operation of the worker of the machine, but the configuration for reflecting the operation in the operation of the control valve 5 is not particularly limited.

In the first drive state, the first inlet / outlet port 14 and the first main line 16 are connected to the discharge side of the pump 3, and the second inlet / outlet port 15 and the second main line 17 are connected to the tank 4. In the second drive state, the second inlet / outlet port 15 and the second main line 17 are connected to the discharge side of the pump 3, and the first inlet / outlet port 14 and the first main line 16 are connected to the tank 4. The inlet pressure PA based on the discharge pressure of the pump 3 is supplied to the first inlet / outlet port 14 in the first drive state, and is supplied to the second inlet / outlet port 15 in the second drive state. In the stopped state, the pair of inlet / outlet ports 14 and 15 are shut off from the pump 3 and the tank 4. The control valve 5 is shown as a three-position direction switching valve only as an example, and any circuit configuration may be adopted as long as the state can be switched.

The hydraulic pressure driving device 10 according to the present embodiment includes a hydraulic tilting mechanism 18 that tilts the swash plate 12. The tilting mechanism 18 includes a piston 19 connected to the swash plate 12, a regulator 20 that controls the supply and discharge of pressure liquid to the piston 19, and a feedback mechanism 29 that feeds back the tilt angle of the swash plate 12 to the regulator 20. include.

The piston 19 has a first liquid chamber 19a and a second liquid chamber 19b. When the pressure liquid is supplied to and discharged from the liquid chambers 19a and 19b, the piston 19 moves in the axial direction thereof to change the tilt angle of the swash plate 12.

The regulator 20 is, for example, a sleeve spool valve. The feedback mechanism 29 is connected to the swash plate 12 and the sleeve of the regulator 20. The urging force of the spring 21 and the pressing force of the cylinder 22 acting in opposite directions act on the spool of the regulator 20. A command pressure line 23 is connected to the liquid chamber of the cylinder 22, and the command pressure Pi is supplied to the cylinder 22 from the outside of the hydraulic pressure drive device 10 via the command pressure line 23, and the cylinder 22 becomes the command pressure Pi. The corresponding pressing force is applied to the spool.

The regulator 20 has a primary pressure port 20a, a drain port 20b and a secondary pressure port 20c. The secondary pressure port 20c is connected to the first liquid chamber 19a of the piston 19 via the secondary pressure line 24. The primary pressure port 20a is connected to the tilt control line 30.

The hydraulic pressure drive device 10 includes a high pressure selection valve 31 and a tilt control line 30. The high-pressure selection valve 31 is connected to the upstream branch portions 30a and 30b branching from the pair of main lines 16 and 17, respectively. The high pressure selection valve 31 selects the higher pressure among the pressures of the pair of main lines 16 and 17, and outputs the pressure to the tilt control line 30. The tilt control line 30 connects the high pressure selection valve 31 to the tilt mechanism 18. The tilt control line 30 has a common portion 30c connected to the high-pressure selection valve 31 and a pair of downstream branch portions 30d and 30e that are bifurcated downstream of the common portion 30c. One downstream branching portion 30d connects the common portion 30c to the second liquid chamber 19b of the piston 19, and the other downstream branching portion 30e connects the common portion 30c to the primary pressure port 20a of the regulator 20.

The hydraulic pressure drive device 10 includes a supply line 40 that merges with the tilt control line 30 and supplies the pressure liquid to the tilt mechanism 18. The supply line 40 is connected to a common portion 30c or a pair of downstream branch portions 30d and 30e in the tilt control line 30. The servo pressure Ps can be supplied to the piston 19 and the regulator 20 from the outside of the hydraulic pressure drive device 10 via the supply line 40 and the pair of downstream branch portions 30d and 30e. The supply line 40 is provided with a tilting mechanism 18 and a check valve 41 for preventing the backflow of pressure liquid from the tilting control line 30.

The hydraulic pressure drive device 10 includes an opening / closing mechanism 35 that opens / closes the tilt control line 30 based on predetermined conditions. The opening / closing mechanism 35 is particularly provided in the common portion 30c. When the opening / closing mechanism 35 is in the closed state, the pressure liquid flows from the pair of main lines 16 and 17 to both the piston 19 and the regulator 20 regardless of which of the pair of main lines 16 and 17 has the higher pressure. Can be blocked. On the other hand, since the common portion 30c is opened and closed, the servo pressure Ps can be supplied to the piston 19 and the regulator 20 via the supply line 40 and the pair of downstream branch portions 30d and 30e.

In the present embodiment, the opening / closing mechanism 35 is composed of an electromagnetic opening / closing valve 36. As an example, the electromagnetic on-off valve 36 is a normally open type, and is configured to close the common portion 30c when a closing command signal is output from the control device 9. The control device 9 determines the success or failure of the above-mentioned predetermined condition, and outputs a closure command signal when the condition is satisfied.

As an example, this predetermined condition includes the condition that the control valve 5 is in the stopped state described above. When torque is applied to the output shaft 10a from the outside of the machine via the work machine in this stopped state, the hydraulic motor 13 is cut off from the pump 3 and the tank 4 of the hydraulic circuit 2, but the liquid is liquid. The phenomenon in which the pressure motor 13 (rotary portion) rotates is called "slip". Slip is generated by a liquid leak that occurs in the hydraulic drive device 10. If there is no opening / closing mechanism 35, the pressure liquid on the high pressure side of the pair of main lines 16 and 17 is supplied to the piston 19 and the regulator 20 via the high pressure selection valve 31 and the common portion 30c. Liquid leakage is likely to occur in the piston 19 and the regulator 20, which may increase the degree of slippage.

In the present embodiment, the opening / closing mechanism 35 closes the tilt control line 30 in such a stopped state. As a result, the pair of main lines 16 and 17 are cut off from the tilting mechanism 18 which is likely to cause liquid leakage. Therefore, deterioration of holding performance (slip performance) can be suppressed.

Since the servo pressure Ps can be supplied to the tilting mechanism 18 via the supply line 40 even in the stopped state, the tilting angle of the swash plate 12 is changed even when the opening / closing mechanism 35 closes the tilting control line 30. Control (control to change the capacity of the hydraulic motor 13) can be continuously executed. The common portion 30c is provided with a check valve 39 for preventing the servo pressure Ps from flowing back to the main lines 16 and 17, so that the hydraulic motor 13 is protected by the check valve 39. The check valve 39 is arranged in series with the electromagnetic on-off valve 36. In the illustrated example, the check valve 39 is arranged on the side (downstream side) closer to the tilting mechanism 18 with respect to the electromagnetic on-off valve 36, but it may be arranged in the opposite direction.

Since the on-off mechanism 35 is composed of an electromagnetic on-off valve, the signal may be supplied / stopped according to the success or failure of the conditions, and the above-mentioned operation can be easily realized.

Hereinafter, the hydraulic pressure drive device according to the second to sixth embodiments will be described focusing on the difference from the first embodiment.

(Second and third embodiments)
As shown in FIG. 2, in the hydraulic pressure drive device 210 according to the second embodiment, the on-off mechanism 235 is configured by a pilot-type on-off valve 236 instead of the electromagnetic on-off valve of the first embodiment. The pilot type on-off valve 236 is a normally open type spool valve, and is configured to close the common portion 30c of the tilt control line 30 by receiving a signal pressure. Even with this configuration, the signal may be supplied / stopped according to the success or failure of the conditions, and the operation described as the first embodiment can be easily realized.

The signal pressure for the opening / closing mechanism 235 is supplied from the outside of the hydraulic pressure drive device 210 via the signal pressure line 23b branched from the command pressure line 23 that supplies the command pressure Pi to the piston of the regulator 20. In this way, the command pressure Pi supplied to the regulator 20 is also supplied to the pilot type on-off valve 236 as a signal pressure, and the opening / closing mechanism 235 can be opened / closed according to the command pressure Pi. , The signal pressure supply source and supply path for the opening / closing mechanism 235 can be simplified.

In this case, when the condition that the command pressure Pi is established is satisfied, the opening / closing mechanism 235 closes the tilt control line 30. FIG. 2 illustrates a so-called negative control, and when the command pressure Pi rises, the servo pressure Ps is supplied to the first liquid chamber 19a and the tilt angle becomes small. This is an example, and may be configured as a so-called positive control (the tilt angle increases when the command pressure Pi rises).

As shown in FIG. 3, in the hydraulic pressure drive device 310 according to the third embodiment, the opening / closing mechanism 335 is composed of a poppet type pilot type opening / closing valve 336. Similar to the second embodiment, the signal pressure is supplied to the on-off valve 336 from the outside of the hydraulic pressure drive device 310 via the signal pressure line 23b branched from the command pressure line 23. The on-off valve 336 is based on the magnitude relationship between the high pressure selected by the high-pressure selection valve 31, the set pressure set by the spring provided on the on-off valve 336, and the signal pressure supplied via the signal pressure line 23b. Opens and closes the common portion 30c of the tilt control line 30. Also in this configuration, the same operation as that of the first embodiment and the second embodiment can be obtained. Although FIG. 3 exemplifies the so-called negative control, it can also be applied to the so-called positive control in the same manner as in the second embodiment.

(Fourth and fifth embodiments)
As shown in FIGS. 4 and 5, in the hydraulic pressure drive devices 410 and 510 according to the fourth embodiment and the fifth embodiment, an opening / closing mechanism is provided on the tilt control line 30 from the tilt mechanism 18. It is provided with a check valve 39 for preventing backflow to the main lines 16 and 17, and a switching mechanism for switching whether or not high-pressure pressure liquid can be supplied via the supply line 40 according to the success or failure of predetermined conditions. The check valve 39 is interposed on the common portion 30c of the tilt control line 30.

With reference to FIG. 4, in the fourth embodiment, the switching mechanism of the opening / closing mechanism 435 is configured by the control valve 436 interposed in the supply line 40. The control valve 436 has a first inlet port, a second inlet port and an outlet port. The outlet port is connected to the tilt control line 30 via the supply line 40. The control valve 436 is configured to switch between a state in which the outlet port is connected to the first inlet port (first state) and a state in which the outlet port is connected to the second inlet port (second state). Servo pressure Ps is supplied to the first inlet port, and closing control pressure Py set to a high pressure to close the tilt control line 30 is supplied to the second inlet port. The control valve 436 is a solenoid valve as an example, and is usually in the first state. When the closing command signal is output from the control device 9, the first state is switched to the second state. Similar to the first embodiment, the control device 9 outputs a closing command signal to the opening / closing mechanism 435 (control valve 436) when a predetermined condition is satisfied.

The closing control pressure Py is set higher than the hydraulic pressure flowing through the main lines 16 and 17. Therefore, when the control valve 436 is in the second state, the check valve 39 on the tilt control line 30 is closed regardless of which of the main lines 16 and 17 is selected by the high pressure selection valve 31. As a result, even if a valve for opening and closing is not provided on the tilt control line 30, the tilt control line 30 is closed under a predetermined condition and the main line 16 is closed in the same manner as in the first embodiment. , 17 can be cut off from the tilting mechanism 18. Further, under this situation, the closing control pressure Py can be supplied to the piston 19 and the regulator 20, and the command pressure Pi can be supplied to the cylinder 22 of the regulator 20 independently of the signal supply for the opening / closing mechanism 435. The tilt angle control of the swash plate 12 can be continuously executed.

With reference to FIG. 5, in the fifth embodiment, the switching mechanism of the opening / closing mechanism 535 is configured by the control valve 536 interposed in the supply line 40. The control valve 536 has a primary pressure port, a secondary pressure port, and a drain port, and the secondary pressure port is connected to the tilt control line 30 via a check valve 41. Servo pressure Ps is supplied to the primary pressure port. The servo pressure Ps according to the present embodiment is set to be higher than the hydraulic pressure flowing through the main lines 16 and 17, similarly to the closing control pressure Py according to the fourth embodiment.

The control valve 536 is a proportional solenoid valve as an example, and the hydraulic pressure output to the secondary pressure port can be adjusted based on the current value of the closing command signal output from the control device 9. The control device 9 outputs a closing command signal equal to or higher than a predetermined current value to the opening / closing mechanism 535 (control valve 536) when a predetermined condition is satisfied. As a result, the check valve 39 on the tilt control line 30 is closed regardless of which of the main lines 16 and 17 is selected by the high pressure selection valve 31 in the same manner as in the fourth embodiment. As a result, the tilt control line 30 can be closed under predetermined conditions to shut off the main lines 16 and 17 from the tilt mechanism 18. Further, under this situation, the servo pressure Ps (secondary pressure) can be supplied to the piston 19 and the regulator 20, and the command pressure Pi is supplied to the cylinder 22 of the regulator 20 independently of the signal supply to the opening / closing mechanism 535. Therefore, the tilt angle control of the swash plate 12 can be continuously executed.

(Sixth Embodiment)
As shown in FIG. 6, in the hydraulic pressure drive device 610 according to the sixth embodiment, the opening / closing mechanism 635 is based on the difference between the pressure output from the high pressure selection valve 31 and the pressure (servo pressure Ps) of the supply line 40. It is composed of a pilot type on-off valve that opens and closes the tilt control line 30 (particularly, the common portion 30c thereof). The on-off valve is a spool valve, and the pressure output from the high-pressure selection valve 31 acts on one end of the spool, and the servo pressure Ps acts on the other end of the spool. The pressure receiving area at one end of the spool and the pressure receiving area at the other end of the spool may be the same or different. If they are different, the pressure receiving area at the other end of the spool may be larger than the pressure receiving area at one end of the spool. In that case, even if the servo pressure Ps is smaller than the pressure output from the high pressure selection valve 31, the opening / closing mechanism 635 can close the tilt control line 30.

Although the embodiments have been described so far, the above configuration is merely an example, and can be appropriately added, changed, and / or deleted within the scope of the present invention. In either embodiment, the hydraulic circuit 2 is configured as an open circuit, but the hydraulic circuit may be configured as a closed circuit using a pump that can rotate in both directions.

10 , 210, 310, 410, 510, 610 Hydraulic drive device 11 Casing 12 Swash plate 13 Hydraulic motor 14, 15 Doorway port 16, 17 Main line 18 Tilt mechanism 19 Piston 20 Regulator 30 Tilt control line 35, 235 , 335,435,535,635 Opening and closing mechanism 36 Electromagnetic on-off valve 236,336 Piston type on-off valve 40 Supply line