JP3559985B2 - Parking brake release mechanism for traveling hydraulic motor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a parking brake release mechanism for a traveling hydraulic motor.
[0002]
[Prior art]
With reference to FIG. 2, a control circuit of a traveling hydraulic motor (hereinafter, simply referred to as a traveling motor) used for a hydraulic excavator, an asphalt finisher, a bulldozer, and the like will be described. This control circuit controls the operation of the pair of left and right traveling motors, and includes a parking brake control circuit that brakes with a mechanical force such as a spring and releases the braking with hydraulic pressure.
[0003]
When the driver operates the remote control valves 2a and 2b with an operation pedal, an operation lever, or the like, the direction control valves 6a and 6b are operated by pilot pressure oil from the pilot pump 4. The direction control valves 6a and 6b control the direction, flow rate, and the like of hydraulic oil for driving a traveling motor discharged from the main pumps 8a and 8b.
[0004]
Each of the traveling motor drive lines 12a and 12b connected to the left and right traveling motors 10a and 10b from the main pumps 8a and 8b via the direction control valves 6a and 6b is provided with a counter balance valve 14, a relief valve 16, and the like. I have. The counter balance valve 14 prevents the inertial motion due to the load of the traveling motors 10a, 10b at the neutral position. The relief valve 16 regulates the hydraulic pressure of the traveling motors 10a, 10b.
[0005]
A brake hydraulic line 18 drawn from one of the output ports of the counter balance valve 14 is connected to a brake operation delay valve 20 having a built-in throttle and a brake release pressure supply / discharge line 22 through a housing of the traveling motors 10a and 10b. Is connected to a cylinder 24a of a parking brake 24 for traveling motor braking incorporated therein. A brake release pressure discharge line 26 of the brake operation delay valve 20 is connected to a drain line 28.
[0006]
The parking brake 24 presses a friction plate provided on an output shaft or a rotating body of the traveling motors 10a and 10b with a friction plate of a housing by a brake piston 24c urged by a brake operating spring 24b. 10b is respectively braked.
[0007]
The release of the parking brake 24 is performed by supplying pressure oil to the cylinder 24a and removing the urging force by the brake operating spring 24b. When the remote control valves 2a and 2b are operated to drive the traveling motors 10a and 10b to supply hydraulic oil from the direction control valves 6a and 6b to the counter balance valve 14, the counter balance valve 14 is switched by the supply of the hydraulic oil. And supply the operating oil to the traveling motors 10a and 10b. At this time, this hydraulic oil also flows through the brake hydraulic line 18, is supplied to the brake operation delay valve 20, switches the delay valve 20, and further enters the brake release side of the cylinder 24 a through the brake release pressure supply / discharge line 22. The brake piston 24c is moved against the brake operating spring 24b to release the parking brake 24 from braking.
[0008]
When the parking brake 24 is released and the direction control valves 6a and 6b are returned to the neutral position by operating the remote control valves 2a and 2b to stop the rotating traveling motors 10a and 10b, the counter balance valve 14 is also in the neutral position (FIG. 2), the traveling motors 10a and 10b are stopped because the supply of the hydraulic oil is stopped, and the supply of the pressure oil of the brake hydraulic line 18 to the parking brake 24 is also cut off. Is switched by the return spring (the position shown in FIG. 2), the hydraulic oil in the cylinder 24a of the parking brake 24 is pushed out by the brake piston 24c which receives the restoring force of the brake operating spring 24b, and the throttle in the brake operating delay valve 20 is removed. After that, it is drained from the drain line 28 to the tank. Then, the brake piston 24c slowly moves toward the brake operation side by the throttle effect of the brake operation delay valve 20, and brakes the traveling motors 10a and 10b.
[0009]
The traveling motors 10a and 10b are constituted by variable displacement motors, and the displacement is changed by changing the tilt angle of the swash plate 11a by the piston 11b. The driving pressure oil of the traveling motor drawn out from between a pair of check valves 30 provided on the traveling motor drive lines 12a and 12b connected to the traveling motors 10a and 10b is connected to the piston 11b by a two-speed switching valve 32 for speed switching. , The supply and discharge are switched, and the reciprocating operation is performed.
[0010]
The second speed switching valve 32 is switched by a speed switching pilot pressure supplied from a speed switching valve 34 via a pilot line 36. The speed switching valve 34 is constituted by an electromagnetic valve, and supplies or interrupts the supply of pilot pressure oil discharged from the pilot pump 4 to the pilot line 36.
[0011]
In the state where the speed switching valve 34 does not supply the pilot pressure oil to the second speed switching valve 32 (the state shown in FIG. 2), the second speed switching valve 32 is positioned on the lower speed side (the position shown in FIG. 2) by the return spring. The pistons 11b of the traveling motors 10a and 10b fix the swash plate 11a to the large capacity (large tilt angle) side by the pressurized oil supplied through the second-speed switching valve 32. The number of rotations is reduced by increasing the amount of oil per rotation, and the traveling motors 10a and 10b are rotated at a low speed.
[0012]
When the speed switching valve 34 supplies the pilot pressure oil to the second speed switching valve 32, the second speed switching valve 32 is positioned on the high speed side against the return spring. The pistons 11b of the traveling motors 10a and 10b fix the swash plate 11a to the small capacity (small tilt angle) side by the pressurized oil supplied through the second-speed switching valve 32. The amount of oil per rotation is reduced to increase the number of rotations, and the traveling motors 10a and 10b are rotated at high speed.
[0013]
[Problems to be solved by the invention]
The parking brake 24 in the conventional traveling motor control circuit of the above-described embodiment has the following problems to be solved. That is, in order to use a high-pressure motor driving pressure (for example, 370 kgf / cm ² ) supplied through the counter balance valve 14 as the parking brake release hydraulic pressure, the parking brake 24 has a thick structure capable of withstanding high pressure or a high pressure. Strength members must be used. Therefore, there are problems such as an increase in the size of the traveling motors 10a and 10b incorporating the parking brake 24, an increase in weight and an increase in cost.
[0014]
It is also possible to add a new pilot pressure supply system to the control circuit of the traveling motor so that the parking brake 24 can be controlled at a low pressure. However, when such a pilot system is added, a pressure reducing mechanism must be added. Alternatively, the pilot pressure output from the remote control valves 2a and 2b is selected and used by adding a plurality of shuttle valves, and additional hose piping is required, which causes a problem of increased cost. .
[0015]
The present invention has been made in view of the above facts, and the technical problem thereof is that the parking brake can be controlled at a low pressure without significantly modifying the control circuit of the traveling motor, and the conventional high pressure control is performed. An object of the present invention is to provide a travel motor parking brake release mechanism that eliminates problems such as an increase in the size, weight, and cost of the travel motor.
[0016]
[Means for Solving the Problems]
In the present invention, a traveling hydraulic motor, a pilot line for supplying a pilot pressure for switching the speed of the traveling hydraulic motor, and a drive line for the traveling hydraulic motor are provided as a parking brake release mechanism for the traveling motor that solves the above technical problem. And a counter balance valve provided in the control circuit of the traveling motor, which supplies the operating hydraulic pressure to the parking brake release mechanism of the traveling hydraulic motor that releases the parking brake of the traveling hydraulic motor by supplying the operating hydraulic pressure. the hydraulic line brake which branches from 該Pa Lee lot lines, connected to the parking brake via a 該Ka counter balance valve, the parking brake release mechanism of the traveling hydraulic motor, wherein there is provided that.
[0017]
Since the pilot pressure for switching the speed, which is much lower than the motor driving pressure, is used as the operating oil pressure of the parking brake, there is no need for the parking brake to have a structure that can withstand high pressure. Since the brake hydraulic line is connected to the existing speed switching pilot line via the counter balance valve, the addition of piping and the like can be minimized.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of a parking brake release mechanism of a traveling hydraulic motor configured according to the present invention will be described in more detail with reference to FIG. In FIG. 1, substantially the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.
[0019]
Brake hydraulic lines 38, 18 for supplying operating hydraulic pressure for releasing the parking brakes 24 of the traveling hydraulic motors (hereinafter simply referred to as traveling motors) 10a, 10b are used to control the speed switching pilot pressure of the traveling motors 10a, 10b. The pilot line 36 branches off and is connected to the parking brake 24 via a counter balance valve 44 of a drive line of the traveling motors 10a and 10b.
[0020]
A pipeline branch section 40 is provided in the pilot line 36, and the brake hydraulic line 38 is branched from the pipeline branch section 40 to each input port 44 a of the counter balance valve 44. The output port 44b selectively connected to the input port 44a of the counter balance valve 44 by the operation of the counter balance valve 44 is driven by the brake hydraulic line 18 via the brake operation delay valve 20 and the brake release pressure supply / discharge line 22. The motors 10a and 10b are connected to cylinders 24a of parking brakes 24 for running motor braking built in housings of the motors, respectively.
[0021]
The counterbalance valve 44 is basically the same as the conventional counterbalance valve 14, except that an input port 44a through which the brake hydraulic line 38 is guided is additionally formed. At the neutral position of the counterbalance valve 44 (the position shown in FIG. 1), the communication between the input port 44a and the output port 44b to which the brake hydraulic line 18 is connected is cut off, and the counterbalance valve 44 is turned to the direction control valve 6a, When the position is switched from the neutral position by 6b (traveling motor operating position), the input port 44a and the output port 44b are communicated. The communication between the traveling motor drive lines 12a and 12b and the brake hydraulic line 18 is interrupted.
[0022]
To the pilot line 36, the pilot pressure oil from the pilot pump 4 is controlled in two stages by the speed switching valve 42 and output. The speed switching valve 42 is constituted by an electromagnetic proportional pressure reducing valve, and in accordance with an input electric signal 43, discharges oil from the pilot pump 4 to a predetermined low pressure P1 for low speed switching (for example, 22 kgf / cm ² ) and a high speed switching oil. The pressure is reduced to a high pressure P2 (for example, 40 kgf / cm ² ) and output.
[0023]
The second speed switching valve 32 receives the speed switching pilot oil pressure P1 or P2 supplied from the speed switching valve 42 via the pilot line 36, and changes from the low speed side to the high speed side when a predetermined specified pressure P3 (for example, 35 kgf / cm ² ) is reached. Is switched to The specified pressure P3 is set so that the second speed switching valve 32 is not switched at the low pressure P1 for low speed switching, but is switched to the high speed side at the high pressure P2 for high speed switching exceeding the specified pressure P3. The parking brake 24 is configured to be able to release the braking at least with the low-speed switching low pressure P1.
[0024]
The operation of the parking brake release mechanism of the traveling hydraulic motor as described above with reference to FIG. 1 will be described.
[0025]
When the driver operates the remote control valves 2a and 2b, the directional control valves 6a and 6b are operated by the pilot pressure oil from the pilot pump 4, and the hydraulic oil for driving the traveling motor discharged from the main pumps 8a and 8b is released. The power is supplied to the traveling motors 10a and 10b via the counter balance valve 44 and the traveling motor drive lines 12a and 12b.
[0026]
In a state where the speed switching valve 42 outputs the pilot pressure oil of the low pressure P1 for low speed switching to the second speed switching valve 32, the second speed switching valve 32 is positioned on the low speed side (the position shown in FIG. 2) and the traveling motor 10a , 10b are kept in a low speed state. In a state where the speed switching valve 42 supplies the high-pressure P2 pilot pressure oil for high-speed switching to the second speed switching valve 32, the second speed switching valve 32 is positioned on the high speed side, and the traveling motors 10a and 10b are maintained in the high speed state. Is done.
[0027]
When the pilot pressure of the pilot line 36, which is the output of the speed switching valve 42, is either the low pressure P1 for low speed switching or the high pressure P2 for high speed switching, the brake hydraulic line 38 branched from the pilot line 36, The cylinder 24a of the parking brake 24 is lower in pressure than the motor driving pressure of the traveling motor drive lines 12a and 12b via the valve 44 and the hydraulic line 18 for braking, but has a sufficient brake release pressure to release the parking brake 24. The brake piston 24c is supplied to release the clamping state between the friction plates provided on the output shafts or rotating bodies of the traveling motors 10a and 10b and the rotating body and the friction plates of the housing to brake the traveling motors 10a and 10b. Cancel.
[0028]
As described above, the present invention uses the low-pressure speed switching pilot pressure instead of the high-pressure motor drive pressure to release the brake of the traveling motor. The traveling motor can be made compact. Further, it is not necessary to use a high-strength member for the parking brake component, add a pressure reducing mechanism to the control circuit of the traveling motor, or add a plurality of shuttle valves.
[0029]
Furthermore, a hydraulic line for braking for releasing the parking brake is connected to the parking brake via a counterbalance valve of the drive motor drive line by branching a pilot line for switching the speed of the drive motor. Since the connection from the pilot line to the counterbalance valve may be connected by a flow path formed in a pipe or a motor housing, a new modification can be minimized.
[0030]
As described above, the present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above-described embodiments, and can be variously modified or modified within the scope of the present invention. For example, a pilot pressure output by an electromagnetic proportional pressure reducing valve is used as the speed switching pilot pressure of the traveling motor. However, the means for outputting the pilot pressure is not limited to this electromagnetic proportional pressure reducing valve. The source may be connected via a switching valve.
[0031]
【The invention's effect】
According to the parking brake release mechanism of the traveling hydraulic motor configured according to the present invention, the traveling brake can be controlled at a low pressure without significantly modifying the control circuit of the traveling motor, and the traveling is controlled by the conventional high pressure. A parking brake release mechanism for a traveling motor that eliminates problems such as an increase in the size, weight, and cost of a motor is provided.
[Brief description of the drawings]
FIG. 1 is a control circuit diagram of a traveling hydraulic motor including a parking brake release mechanism configured according to the present invention.
FIG. 2 is a control circuit diagram of a conventional traveling hydraulic motor.
[Explanation of symbols]
10a: Travel hydraulic motor (travel motor)
10b: Travel hydraulic motor (travel motor)
14: Counter balance valve 18: Hydraulic line for brake 20: Brake operation delay valve 24: Parking brake 32: Second speed switching valve 34: Speed switching valve 36: Pilot line 38: Hydraulic line for braking 42: Speed switching valve 44: Counter Balance valve

Claims (1)

A control circuit for the traveling motor having a traveling hydraulic motor, a pilot line for supplying a pilot pressure for switching the speed of the traveling hydraulic motor, and a counterbalance valve provided on a driving line of the traveling hydraulic motor; In the parking brake release mechanism of the traveling hydraulic motor that releases the parking brake of the traveling hydraulic motor by supplying
Hydraulic lines for brakes for supplying the manipulation hydraulic branches from 該Pa Lee lot lines, connected to the parking brake via a 該Ka counter balance valve, the travel hydraulic motor of the parking brake release mechanism, characterized in that.

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