JP7185513B2 - hydraulic drive - Google Patents

Description

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

Hydraulic motors are generally used as driving sources for working 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 swivel base of a backhoe. The swashplate is tilted by a hydraulic tilting mechanism. The tilting mechanism includes a piston connected to the swash plate and a regulator that controls the hydraulic pressure that actuates the piston. The high pressure side of the inlet/outlet pressure is supplied to the rotating portion that slides and rotates on the swash plate, and is also distributed to the regulator as the primary pressure.

JP 2008-82127 A

By the way, hydraulic motors are required to have "holding performance" or "slip performance". A 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 and the rotating part rotates. If this rotation is small, it is said that the holding performance is high.

If the high-pressure side of the inlet/outlet pressure is led to the regulator and the piston as in the conventional art, fluid leakage from the regulator and the piston will occur if torque is applied from the outside when the outlet-side port is closed. Increased liquid leakage inside the motor causes deterioration of holding performance.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a hydraulic drive device that suppresses deterioration in holding performance.

A hydraulic drive device according to one aspect 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 hydraulic motors connecting the pair of inlet/outlet ports to the hydraulic motor. a main line, a hydraulic tilting mechanism for tilting the swash plate, a high pressure selection valve for selecting and outputting the higher one of the pressures of the pair of main lines, and the high pressure selection valve for the tilting. A tilting control line connected to a tilting mechanism and an opening/closing mechanism opening and closing the tilting control line based on a predetermined condition are provided.

According to the above configuration, when the tilting control line is closed, the main line is blocked from the tilting mechanism, so 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 pressure liquid to the tilt mechanism may be further provided.

According to the above configuration, even in a situation where the tilting 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 hydraulic pressure from the supply line tilts the tilting mechanism. A rolling mechanism can be operated. Even if the tilting control line is closed by the opening/closing mechanism, the capacity control of the motor can be continuously executed.

The opening/closing mechanism may be an electromagnetic opening/closing valve or a pilot type opening/closing valve.

According to the above configuration, it is only necessary to supply/stop the electrical signal or the signal pressure depending on whether the condition is successful or not, and the above-described effects can be easily realized.

The tilting mechanism includes a piston connected to the swash plate, and a regulator that controls the supply and discharge of pressure fluid to and from the piston. The command pressure to be supplied may also be supplied to the pilot operated 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, the opening/closing mechanism is provided on the tilting control line, and a check valve prevents reverse flow from the tilting mechanism to the main line; A switching mechanism for switching whether or not the high-pressure liquid is supplied through the supply line according to whether or not a predetermined condition is met.

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

ADVANTAGE OF THE INVENTION According to this invention, the hydraulic drive device which suppressed the fall of holding|maintenance performance can be provided.

1 is a circuit diagram showing a hydraulic drive device according to a first embodiment; FIG. It is a circuit diagram showing a hydraulic drive device according to a second embodiment. It is a circuit diagram showing a hydraulic drive device according to a third 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 drive device 10 according to the first embodiment. A hydraulic drive device 10 according to the embodiment is mounted on a construction machine, an industrial machine, or an agricultural machine (hereinafter simply referred to as machine). The machine is provided with a hydraulic drive unit 1 that drives a working machine such as a swivel base. The hydraulic drive unit 1 includes a hydraulic circuit 2 that hydraulically drives the working machine, and a control device 9 that controls the operation of the hydraulic circuit 2 . The hydraulic drive device 10 is one element that constitutes the hydraulic circuit 2 and serves as an actuator that drives the work machine. An output shaft 10a of the hydraulic drive device 10 is connected to a working machine so as to be capable of power transmission.

The hydraulic circuit 2 includes a hydraulic drive device 10 , a pump 3 that supplies hydraulic pressure to the hydraulic drive device 10 , a tank 4 that stores hydraulic fluid, and a hydraulic fluid from the pump 3 to the hydraulic 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 that accommodates it. Hydraulic motor 13 includes a swash plate 12 . The hydraulic motor 13 is a rotary portion that rotates while sliding on the swash plate 12 . Although illustration of the detailed structure is omitted, the hydraulic motor 13 includes a cylinder block rotatably supported by the casing 11, a plurality of pistons inserted into the cylinder block so as to move back and forth, and a swash plate attached to the tip of each piston. Includes a shoe that slides on 12 . 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.

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

The hydraulic motor 13 is rotatable in both directions. The control valve 5 of the hydraulic circuit 2 rotates the hydraulic motor 13 in a first direction in a first drive state (right function in FIG. 1) and in a 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 (center function in FIG. 1) in which the hydraulic motor 13 is stopped. The state is switched according to the operation of the operator of the machine, but the configuration for reflecting the operation on the operation of the control valve 5 is not particularly limited.

In the first driving 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 driving 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 . An inlet pressure PA based on the discharge pressure of the pump 3 is supplied to the first inlet/outlet port 14 in the first driving state and to the second inlet/outlet port 15 in the second driving state. In the stopped state, the pair of inlet/outlet ports 14 and 15 are blocked from the pump 3 and the tank 4 . It should be noted that the illustration of the control valve 5 as a three-position directional switching valve is merely an example, and any circuit configuration may be employed as long as it can realize switching of states.

The hydraulic drive device 10 according to this 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 fluid to the piston 19 , and a feedback mechanism 29 that feeds back the tilting angle of the swash plate 12 to the regulator 20 . include.

The piston 19 has a first fluid chamber 19a and a second fluid chamber 19b. The supply and discharge of pressure fluid to and from these fluid chambers 19a and 19b causes the piston 19 to move in its axial direction to change the tilt angle of the swash plate 12 .

Regulator 20 is, by way of example, a sleeve and spool valve. A feedback mechanism 29 is connected to the swashplate 12 and the sleeve of the regulator 20 . The biasing force of the spring 21 and the pressing force of the cylinder 22 act in opposite directions to the spool of the regulator 20 . A command pressure line 23 is connected to the liquid chamber of the cylinder 22, and a command pressure Pi is supplied from the outside of the hydraulic drive device 10 to the cylinder 22 via the command pressure line 23, and the cylinder 22 reaches the command pressure Pi. A corresponding pressing force is applied to the spool.

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 a secondary pressure line 24. As shown in FIG. The primary pressure port 20 a is connected to the tilt control line 30 .

The hydraulic drive 10 has a high pressure selection valve 31 and a tilt control line 30 . The high pressure selection valve 31 is connected to upstream branch portions 30a and 30b branched from the pair of main lines 16 and 17, respectively. The high pressure selection valve 31 selects the higher pressure of the pair of main lines 16 and 17 and outputs it to the tilt control line 30 . A 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 bifurcated downstream of the common portion 30c. One downstream branch 30 d connects the common portion 30 c to the second fluid chamber 19 b of the piston 19 , and the other downstream branch 30 e connects the common portion 30 c to the primary pressure port 20 a of the regulator 20 .

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

The hydraulic drive device 10 includes an opening/closing mechanism 35 that opens and 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, regardless of which of the pair of main lines 16, 17 is at high pressure, both the piston 19 and the regulator 20 are pressurized from the pair of main lines 16, 17. can be prevented. 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 branches 30d, 30e.

In this embodiment, the opening/closing mechanism 35 is composed of an electromagnetic opening/closing valve 36 . As an example, the electromagnetic opening/closing valve 36 is of 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 whether or not the predetermined conditions are met, and outputs a closing command signal when the conditions are met.

This predetermined condition includes, for example, the condition that the control valve 5 is in the stopped state described above. In this stopped state, when torque is applied to the output shaft 10a from the outside of the machine through the work machine, the hydraulic pressure motor 13 is cut off from the pump 3 and the tank 4 of the hydraulic circuit 2. A phenomenon in which the pressure motor 13 (rotary portion) rotates is called "slip". A slip is caused by a fluid leak occurring within the hydraulic drive 10 . If the opening/closing mechanism 35 were not provided, the pressure fluid on the high pressure side of the pair of main lines 16 and 17 would be supplied to the piston 19 and the regulator 20 via the high pressure selection valve 31 and the common portion 30c. Piston 19 and regulator 20 are prone to leaks, which can increase the degree of slippage.

In this 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 blocked from the tilting mechanism 18, which tends to cause liquid leakage. Therefore, deterioration of retention performance (slip performance) can be suppressed.

Since the servo pressure Ps can be supplied to the tilting mechanism 18 through the supply line 40 even in the stopped state, the tilting angle of the swash plate 12 can be changed even when the opening/closing mechanism 35 closes the tilting control line 30. Control (control for changing the capacity of the hydraulic motor 13 ) can be continuously executed. The common portion 30 c is provided with a check valve 39 that prevents 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 closer to the tilting mechanism 18 (downstream side) than the electromagnetic on-off valve 36, but it may be arranged in reverse.

Since the opening/closing mechanism 35 is composed of an electromagnetic opening/closing valve, it is only necessary to supply/stop a signal depending on whether the conditions are satisfied or not, and the above-described effects can be easily realized.

Hydraulic drive systems according to second to sixth embodiments will be described below, focusing on differences from the first embodiment.

(Second and third embodiments)
As shown in FIG. 2, in the hydraulic drive device 210 according to the second embodiment, the opening/closing mechanism 235 is composed of a pilot type opening/closing valve 236 instead of the electromagnetic opening/closing valve of the first embodiment. The pilot type opening/closing valve 236 is a normally open spool valve, and is configured to close the common portion 30c of the tilting control line 30 upon receipt of signal pressure. With this configuration as well, it is only necessary to supply/stop the signal depending on whether the conditions are met or not, and the effects described as the first embodiment can be easily realized.

A signal pressure for the opening/closing mechanism 235 is supplied from the outside of the hydraulic drive device 210 via a 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 manner, the command pressure Pi supplied to the regulator 20 is also supplied as a signal pressure to the pilot type on-off valve 236, and the opening/closing mechanism 235 is configured to be able to open and close 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, the opening/closing mechanism 235 closes the tilting control line 30 when the condition that the command pressure Pi rises is satisfied. FIG. 2 illustrates a so-called negative control, in which when the command pressure Pi rises, the servo pressure Ps is supplied to the first liquid chamber 19a to reduce the tilt angle. This is just an example, and may be so-called positive control (the tilt angle increases when the command pressure Pi rises).

As shown in FIG. 3 , in the hydraulic drive device 310 according to the third embodiment, the opening/closing mechanism 335 is configured by a poppet type pilot operated opening/closing valve 336 . As in the second embodiment, the signal pressure is supplied from the outside of the hydraulic drive device 310 to the on-off valve 336 via the signal pressure line 23b branched from the command pressure line 23. FIG. 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 in the on-off valve 336, and the signal pressure supplied via the signal pressure line 23b, the on-off valve 336 opens and closes the common portion 30 c of the tilt control line 30 . Also in this configuration, the same effects as in the first and second embodiments can be obtained. Although FIG. 3 also exemplifies a so-called negative control, it can also be applied to a 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 drive devices 410 and 510 according to the fourth and fifth embodiments, the opening/closing mechanism is provided on the tilt control line 30 and is connected to the tilt mechanism 18. It has a check valve 39 that prevents reverse flow to the main lines 16 and 17, and a switching mechanism that switches whether or not the high-pressure liquid is supplied through the supply line 40 depending on whether a predetermined condition is met. The check valve 39 is interposed on the common portion 30 c of the tilt control line 30 .

Referring to FIG. 4 , in the fourth embodiment, the switching mechanism of opening/closing mechanism 435 is constituted by control valve 436 interposed in supply line 40 . Control valve 436 has a first inlet port, a second inlet port and an outlet port. The outlet port is connected to tilt control line 30 via 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). A first inlet port is supplied with a servo pressure Ps and a second inlet port is supplied with a closing control pressure Py set to a high pressure to close the tilt control line 30 . The control valve 436 is, for example, an electromagnetic valve and is normally in the first state. When a closing command signal is output from the control device 9, the state is switched from the first state to the second state. As in 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 16,17. 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 hydraulic pressure 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 can be closed under the predetermined conditions and the main line 16 can be closed as in the first embodiment. , 17 can be disconnected from the tilting mechanism 18 . Further, under this condition, 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. Tilt angle control of the swash plate 12 can be continuously performed.

Referring to FIG. 5, in the fifth embodiment, the switching mechanism of opening/closing mechanism 535 is constituted by control valve 536 interposed in 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 the check valve 41 . A servo pressure Ps is supplied to the primary pressure port. The servo pressure Ps according to this embodiment is set higher than the hydraulic pressure flowing through the main lines 16 and 17, like the closing control pressure Py according to the fourth embodiment.

The control valve 536 is, for example, a proportional solenoid valve, and can adjust the hydraulic pressure output to the secondary pressure port 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 of a predetermined current value or more 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 hydraulic pressures in the main lines 16 and 17 is selected by the high pressure selection valve 31, as in the fourth embodiment. As a result, the tilting control line 30 can be closed under a predetermined condition to block the main lines 16 and 17 from the tilting mechanism 18 . Further, under this condition, the servo pressure Ps (secondary pressure) 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 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 drive device 610 according to the sixth embodiment, the opening/closing mechanism 635 operates based on the difference between the pressure output from the high pressure selection valve 31 and the pressure in the supply line 40 (servo pressure Ps). It is composed of a pilot type on-off valve that opens and closes the tilt control line 30 (in particular, its common portion 30c). The open/close 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 different, the pressure receiving area at the other end of the spool may be larger than the pressure receiving area at the one end of the spool. In that case, the opening/closing mechanism 635 can close the tilt control line 30 even if the servo pressure Ps is lower than the pressure output from the high pressure selection valve 31 .

Although the embodiments have been described so far, the above configuration is merely an example, and additions, changes, and/or deletions can be made as appropriate within the scope of the present invention. Although the hydraulic circuit 2 is configured as an open circuit in any of the embodiments, the hydraulic circuit may be configured as a closed circuit using a bidirectionally rotatable pump.

10, 210, 310, 410, 510, 610 hydraulic drive
11 casing 12 swash plate 13 hydraulic motor
14, 15 inlet/outlet ports 16, 17 main line 18 tilting mechanism 19 piston 20 regulator 30 tilting control line 35, 235, 335 , 435, 535, 635 opening/closing mechanism 36 electromagnetic opening/closing valves 236, 336 pilot type opening/closing valve 40 supply line

Claims (5)

a casing having a pair of inlet and outlet ports;
a variable displacement hydraulic motor that includes a swash plate and is housed in the casing;
a pair of main lines connecting the pair of inlet and outlet ports to the hydraulic motor;
a hydraulic tilting mechanism for tilting the swash plate;
a high pressure selection valve that selects and outputs the higher pressure of the pair of main line pressures;
a tilt control line connecting the high pressure selection valve to the tilt mechanism;
an opening/closing mechanism that opens and closes the tilt control line based on a predetermined condition ;
a supply line that merges with the tilt control line and supplies hydraulic fluid to the tilt mechanism . The hydraulic drive device according to claim 1 , wherein the opening/closing mechanism is an electromagnetic opening/closing valve or a pilot type opening/closing valve. The tilting mechanism comprises a piston connected to the swash plate, and a regulator that controls supply and discharge of pressure liquid to and from the piston,
3. The hydraulic drive device according to claim 2 , wherein when the opening/closing mechanism is a pilot type opening/closing valve, the command pressure supplied to the regulator is also supplied as a signal pressure to the pilot type opening/closing valve. the supply line supplies a higher pressure than the inlet/outlet port;
The opening/closing mechanism is
a check valve provided on the tilting control line for preventing reverse flow from the tilting mechanism to the main line;
2. The hydraulic drive device according to claim 1 , further comprising a switching mechanism that switches whether or not the high-pressure hydraulic fluid is supplied through the supply line depending on whether the predetermined condition is met. The opening/closing mechanism is composed of a pilot type opening/closing valve provided on the tilting control line, and the pressure output from the high pressure selection valve acts on one end of the spool of the pilot type opening/closing valve. The pressure of the supply line acts on the end,
The pilot type on-off valve is configured to be able to open and close the tilt control line based on the two pressures.
Hydraulic drive device according to claim 1 .

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