JP2001027202A - Brake circuit device for turning hydraulic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake circuit device for a turning hydraulic motor capable of executing the brake release of the turning hydraulic motor with good responsiveness even under low temperature. SOLUTION: This brake circuit device for a turning hydraulic motor is provided with a supply-discharge control valve 80 for preloading a pressure chamber 72 of a brake release cylinder 70 to the specified set pressure when the turning hydraulic motor 14 is braked by braking devices 68, 70. The supply-discharge control valve 80 has a throttle 82 for supplying after reducing the pressure of pressure oil from a pilot hydraulic power source 50 in a preload position A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for braking a swing hydraulic motor of a construction machine such as a hydraulic excavator, and more particularly to a brake hydraulic motor for controlling braking and non-braking operations by a brake device. The present invention relates to a brake circuit device.

[0002]

2. Related Art A brake circuit device for a swing hydraulic motor of this type is disclosed, for example, in Japanese Patent Publication No. 6-74034. The brake circuit device according to this publication attaches a brake release cylinder to a mechanical brake device that brakes a swing hydraulic motor, and interlocks the drive and stop of the swing hydraulic motor and the arm cylinder between the brake release cylinder and its hydraulic source. It is configured by interposing a switching valve that is switched.

When the switching valve is switched to its supply position in conjunction with the driving of the swing hydraulic motor or the arm cylinder,
The brake release cylinder receives the supply of pilot pressure from the hydraulic pressure source through the switching valve, and forcibly releases the braking of the turning hydraulic motor by the mechanical brake device. On the other hand, when the swing hydraulic motor and the arm cylinder are stopped, and the switching valve is switched from the supply position to the discharge position in conjunction with this,
The pressure oil in the brake release cylinder is discharged through the switching valve, so that the brake release cylinder allows braking of the turning hydraulic motor by the mechanical brake device.

[0004] Therefore, when the swing hydraulic motor and the arm cylinder are stopped, the swing hydraulic motor is in a state of being braked by the mechanical brake device, so that inadvertent swing of the swivel base can be reliably prevented. The braking by the mechanical brake device is released with the start of driving of the motor or the arm cylinder. As a result, smooth driving of the turning hydraulic motor is guaranteed, and the turning power transmission system parts are damaged even when an external force is applied when the arm is driven. Is prevented.

[0005]

In the case of the above-described brake circuit device, the switching valve is switched based on the presence or absence of the pilot pressure, and the pilot pressure is interlocked with a predetermined operation of the swing hydraulic motor or the arm cylinder to control the hydraulic pressure. It comes from a source. Therefore, regarding the switching operation of the switching valve, the responsiveness is greatly affected by the temperature of the pressure oil,
When the temperature of the pressure oil is low and its viscosity is high in cold districts or in winter, it takes time to raise and transmit the pilot pressure even when the swing hydraulic motor is started, and the discharge position of the switching valve There is a delay in the switching operation from the to the supply position.
In such a case, the turning hydraulic motor is driven while being braked by the mechanical brake device, and the mechanical brake device may be damaged.

The present invention has been made in view of the above circumstances, and an object of the present invention is to quickly and surely release the braking of a swing hydraulic motor by a mechanical brake device even when the temperature of pressurized oil is low. It is an object of the present invention to provide a brake circuit device for a swing hydraulic motor that can perform the above.

[0007]

In order to achieve the above-mentioned object, the present invention (claim 1) connects a brake release cylinder of a brake device and a hydraulic power source to at least operate a swing hydraulic motor. Pilot pressure output means for controlling the flow of pilot pressure oil supplied to the brake release cylinder in conjunction therewith, and a supply / discharge circuit for supplying and discharging pressure oil to and from the brake release cylinder based on the operation of the pilot pressure output means. The brake circuit device for a turning hydraulic motor provided includes a preload applying means for preloading a cylinder pressure of a brake release cylinder to a predetermined set pressure while maintaining braking by the brake device.

According to the above-described brake circuit device, at the time of braking of the turning hydraulic motor, the cylinder pressure of the brake release cylinder is already pre-pressed to a predetermined set pressure. The brake release cylinder receives the supply of the pressure oil via the supply / discharge circuit, and releases the braking of the turning hydraulic motor by the brake device. The preload applying means may include pressure adjusting means for adjusting the circuit pressure on the brake release cylinder side to a predetermined set pressure in the supply / discharge circuit (claim 2). In this case, the pressure adjusting means pre-presses the inside of the brake release cylinder using the pressure oil from the hydraulic pressure source.
Specifically, the pressure adjusting means is formed by a valve, a throttle, or the like.

Further, the preload applying means may include a variable means capable of adjusting the set pressure of the pressure adjusting means in accordance with the temperature of the pressure oil. In this case, the lower the temperature of the hydraulic oil, the higher the set pressure of the pressure adjusting means, that is, the higher the preload in the brake release cylinder, and the more stable the responsiveness of the brake release of the swing hydraulic motor can be maintained. Becomes

[0010]

FIG. 1 shows a hydraulic excavator as an example of a construction machine.
The swivel 4 is provided on the upper part of the traveling body having the pivot. The turning table 4 is provided with a working machine 6 and a cabin 7. The work machine 6 includes an undulating boom 8, an arm 10, and a bucket 12,
It is composed of a hydraulic cylinder or the like as an actuator.

As shown in FIG. 2, the turning hydraulic circuit for turning the turning table 4 includes a turning hydraulic motor 14, and is connected to a control valve 20 by a pair of conduits 16, 18. The control valve 20 comprises a four-port three-position directional control valve, two of the four ports m1,
m2 is connected to conduits 16 and 18, respectively. Of the remaining two ports, one port p is connected to a main hydraulic pump 24 via a pump discharge line 22, and the other port t is connected to a tank 28 via a return line 26. The main hydraulic pump 24 is connected to a tank 28 via a suction pipe 30 and is driven to rotate by an engine (not shown). Although not shown,
The pump discharge line 22 is connected to a pressure oil tank 28 via a relief line provided with a relief valve.

The control valve 20 is switched to a neutral position, a left turning position and a right turning position by moving the spool. The movement of the spool is performed by the pilot pressure. For this purpose, the control valve 20 has pressure receiving portions 32, 34 at both ends for receiving the pilot pressure, and is connected to the output ports of the pilot valves 40, 42 by pilot lines 36, 38, respectively. The pilot valves 40 and 42 are three-way valves, and the supply ports and the return ports of these pilot valves are connected to each other via connection pipes 44 and 46. One connecting line 44 is a supply line 48
And the other connecting line 46 is connected to the tank 28 via a return line 52. The pilot hydraulic pressure source 50 is composed of, for example, a sub-hydraulic pump, a relief valve, and a tank 28 that are rotationally driven by an engine, and can discharge pressure oil of a predetermined pressure. Further, the pilot lines 36 and 38 are connected to each other through a communication line 54.
In parallel with the control valve 20, the shuttle valve 5
6 is interposed.

The pilot valves 40 and 42 are selectively operated by a turning lever 58 in the cabin 7. For example, by operating the turning lever 58, one of the pilot valves 42 is switched from the state shown in the figure, and when the supply port and the output port thereof communicate with each other, the hydraulic oil from the pilot hydraulic source 50 is supplied to the control valve 20 through the pilot line 38.
Is supplied as pilot pressure to the pressure receiving portion 34, and the control valve 20 is operated from the neutral position to the right turning side.
As a result, the swing hydraulic motor 1
4 is supplied with pressure oil in one direction, and the turning hydraulic motor 14 drives the turning table 4 to turn rightward by its drive. In this state, since the pilot line 36 communicates with the tank 28 via the pilot valve 40 and the return line 52, the pressure receiving portion 32 of the control valve 20 has a pressure substantially equal to the tank pressure. Pilot line 3
The pilot valve 6 and the pilot line 38 are connected to a shuttle valve 56, respectively. The pilot pressure on the high pressure side is selected by the shuttle valve 56, and the pilot pressure is guided to a line 86 described later.

On the other hand, when the other pilot valve 40 is switched from the state shown in the figure by operating the turning lever 58, in this case, the pressure receiving portion 32 of the control valve 20 is turned on.
As a result, the control valve 20 is operated from the neutral position to the left turning side. in this case,
The turning hydraulic motor 14 is driven by receiving the supply of the pressure oil in the opposite direction, and turns the turning table 4 to the left.

The pipelines 16 and 1 connected to the turning hydraulic motor 14
8 are connected to each other via two communication pipes 60 and 62, and relief valves 64 and 6 are connected to these communication pipes 60 and 62.
6 are interposed. These relief valves 64,
Reference numeral 66 prevents the turning hydraulic motor 14 from being supplied with excessive pressure oil. The turning hydraulic motor 14 is provided with a mechanical brake 68. In the present embodiment, when the turning hydraulic motor 14 is in a stopped state, the mechanical brake 68 is applied by an urging means such as a spring. It is configured to apply a braking force to the rotating shaft (not shown) of the turning hydraulic motor 14 by the force.

On the other hand, the mechanical brake 68 is provided with a brake release cylinder 70 which, when supplied with pressure oil to its pressure chamber 72, contracts against the urging force of a return spring 74. Then, the braking of the turning hydraulic motor 14 by the mechanical brake 68 is released. Conversely, when the pressure oil is discharged from the pressure chamber 72, the brake release cylinder 7
0 is extended by receiving the urging force of the return spring 74, and allows the mechanical hydraulic brake 68 to brake the turning hydraulic motor 14.

In order to supply and discharge pressure oil to and from the brake release cylinder 70, the brake release cylinder 70 and the above-described pilot hydraulic source 50 are connected via a supply / discharge circuit 76. The supply / discharge circuit 76 includes a branch supply line 78 branched from the supply line 48, and the branch supply line 78 is connected to the pressure chamber 72 of the brake release cylinder 70.

A supply / discharge control valve 80 as pilot pressure output means is interposed in the branch supply line 78. The supply / discharge control valve 80 is, for example, a three-port two-direction switching valve. The supply / discharge control valve 80 has a preload position (A) and a supply position (B), and is normally positioned at the preload position (A) by receiving the urging force of the return spring 81. At the preload position (a),
The inlet port a and the outlet port b of the supply / discharge control valve 80 are connected to the upstream line 7 of the branch supply line 78 through the valve passage therein.
The valve passage is connected to a return port c via a throttle 82, while connecting between the downstream passage 8a and the downstream pipe 78b. The return port c is connected to the tank 28 via a return line 84. In contrast, the supply position (b)
, The supply / discharge control valve 80 communicates only between the inlet port a and the outlet port b through the valve passage, and the return port c
Is shut off.

The supply / discharge control valve 80 has a pressure receiving portion 80a on the supply position (b) side.
6 is connected to the shuttle valve 56 described above.
Therefore, when the pilot pressure rises in the communication pipe 54 via the pilot valve 40 or 42 by the operation of the above-mentioned turning lever 58, this pilot pressure is supplied / discharged controlled via the shuttle valve 56 and the pilot pipe 86. It is also applied to the pressure receiving portion 80a of the valve 80, and switches the supply / discharge control valve 80 from the preload position (a) to the supply position (b).

Further, a check valve 90 that allows the supply of pressure oil only to the brake release cylinder 70 side is provided in the downstream pipe line 78b.
A return line 92 extends from a position downstream of the check valve 90, and the return line 92 is connected to the tank 28. A throttle 94 is inserted in the return conduit 92, and the opening of the throttle 94 is set sufficiently smaller than the opening of the throttle 82 incorporated at the preload position (a) of the supply / discharge control valve 80. I have. A drain pipe 96 is connected to the return spring chamber of the brake release cylinder 70, and the drain pipe 96 is connected to a return pipe 92 downstream of the throttle 94.

When the supply / discharge control valve 80 is at the illustrated preload position (A), the pressure oil discharged from the pilot hydraulic power source 50 passes through the branch supply line 78 and the supply / discharge control valve 80 to the branch supply line 78. While being supplied to the downstream pipe 78b, a part thereof is returned to the tank 28 through the above-described throttle 82.
Therefore, the supply / discharge control valve 80 reduces the pressure oil of the pilot hydraulic pressure source 50 and supplies it to the downstream pipe 78b. Further, the pressure oil in the downstream pipe 78 b is supplied to the pressure chamber 72 of the brake release cylinder 70, while part of the pressure oil is released to the tank 28 through the throttle 94 in the return pipe 92. Accordingly, the pressure chamber 72 of the brake release cylinder 70 is supplied further depressurized pilot pressure, the internal pressure of the pressure chamber 72, i.e., cylinder pressure is raised to a predetermined set pressure P _S. Here, the set pressure P _S is determined by the stop 82 and 94 as described above, it stops 82 and 94 is a brake releasing cylinder 70
Of the preload applying means.

When the brake release cylinder 70 is preloaded at the set pressure P _S , the brake release cylinder 70 applies the braking force of the turning hydraulic motor 14 by the mechanical brake 68, that is, the brake torque as shown in FIG. Despite the decrease, the mechanical brake 68 sufficiently exerts the brake torque required for braking the turning hydraulic motor 14 regardless of the decrease.

In such a situation, when the control valve 20 is operated leftward or rightward from the neutral position by the pilot pressure in accordance with the operation of the above-mentioned turning lever 58, the pilot pressure becomes the supply / discharge control valve. 80 pressure receiving part 80a
And the supply / discharge control valve 80 is switched from its preload position (a) to the supply position (b). This supply position (b)
In this case, the pressure oil discharged from the pilot hydraulic pressure source 50 is supplied to the brake release cylinder 70 side without being reduced in pressure by the supply / discharge control valve 80. Accordingly, pressure oil having a pressure close to the original pressure of the pilot hydraulic source 50 is supplied to the pressure chamber 72 of the brake release cylinder 70, and the cylinder pressure is set in accordance with the operation of the operation lever 58 as shown in FIG. It raised rapidly from pressure P _S to its allowable maximum pressure, and the brake torque of the mechanical brake 68 as the brake release cylinder 70 shown in FIG. 4, i.e., immediately release the braking force of hydraulic swing motor 14 . As a result, the swing hydraulic motor 14
Since the braking force can be released before is substantially driven, the overload of the mechanical brake 68 is prevented, and the turning hydraulic motor 14 can be driven smoothly.

In this regard, if the cylinder pressure of the brake release cylinder 70 is not pre-pressed to the set pressure P _S and the pressure oil temperature is low, the operation of the operation lever 58 in FIG. it takes time to start up the cylinder pressure as indicated by a broken line, a delay T _D of the brake release by the mechanical brake 68 is large. In this case, the turning hydraulic motor 14 is driven before the braking is released, and the mechanical brake 68 may be damaged.

Even when the supply / discharge control valve 80 is at the preload position (a), the hydraulic oil from the pilot hydraulic source 50 continues to be supplied to the brake release cylinder 70 and the pilot hydraulic source 5
Since the fluid circulates between the zero and the brake release cylinder 70, the temperature of the pressure oil in the brake circuit device including the pilot pipeline system can be increased. As a result, the responsiveness of braking of the turning hydraulic motor 14 is further improved.

Thereafter, when the turning hydraulic motor 14 is stopped by the returning operation of the turning lever 58 to the rest position, the pilot pressure which has been acting on the supply / discharge control valve 80 until now is also returned to the tank 28, The supply / discharge control valve 80 is in the supply position (b)
To the preload position (a). At this time, the pressure oil between the brake release cylinder 70 and the check valve 90 is returned to the tank 28 only through the throttle 94, so that the pressure in the pressure chamber 72, that is, the cylinder pressure does not suddenly decrease. . Accordingly, the brake release cylinder 70 gradually increases the braking force of the turning hydraulic motor 14 by the mechanical brake 68.
No sudden braking force is applied to the vehicle. Thereafter, when the pressure between the brake release cylinder 70 and the check valve 90 drops below the pressure determined by the supply / discharge control valve 80, the pressure oil from the pilot hydraulic source 50 similarly passes through the supply / discharge control valve 80. is supplied, the cylinder pressure of the brake releasing cylinder 70 is returned to the set pressure P _S.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in FIG.
Supply / discharge control valve 1 comprising an on-off valve instead of supply / discharge control valve 80
A brake circuit device using 00 is shown. In this case, a return pipe 102 extending from the position downstream of the check valve 90 to the tank 28 is connected to the branch supply pipe 78, and the return pipe 102 is connected to a throttle 82 in the supply / discharge control valve 80 and a supply / discharge control valve. 100 are sequentially inserted. The return line 92 having the above-described restriction 94 is connected to the return line 102 at a position upstream of the restriction 82. As is clear from FIG. 5, the supply / discharge control valve 100 is a normally-open valve that is switched from the open position (C) to the closed position (D) when receiving the above-described pilot pressure.

Even in the brake circuit device of FIG. 5, when the turning hydraulic motor 14 is stopped, as in the above-described embodiment,
The supply / discharge control valve 100 in the open position cooperates with the throttles 82 and 94 to increase the cylinder pressure of the brake release cylinder 70 to the set pressure P.
_Start up to _S. On the other hand, when the supply / discharge control valve 100 is closed by receiving the pilot pressure, a closed circuit is formed from the pilot hydraulic source 50 to the brake release cylinder 70, and the original pressure of the pilot hydraulic source 50 is applied to the pressure chamber 72 of the brake release cylinder 70. The braking of the turning hydraulic motor 14 by the supplied mechanical brake 68 is released more quickly.

Referring to FIG. 6, there is shown a brake circuit device in which only the supply / discharge control valve 80 of FIG. 2 is replaced by a supply / discharge control valve 106 comprising an electromagnetic proportional valve. In this case, the supply / discharge control valve 106 has two positions, a preload position (e) and a supply position (f), as in the case of the supply / discharge control valve 80. However, the supply / discharge control valve 106 moves from the preload position (e) to the supply position (f). When the switching operation is performed, the opening degree of the outlet port b, that is, the supply / discharge control valve 106
Is linearly increased.

In controlling the valve opening of the supply / discharge control valve 106, its solenoid 108 is electrically connected to a controller 110, and the controller 110 controls the switching position of the supply / discharge control valve 106, that is, its valve opening. Is output to the solenoid 108. In order to generate the control signal, sensor signals from the pressure sensor 112 and the oil temperature sensor 114 are input to the controller 110. Pressure sensor 112 detects a pilot pressure to control valve 20 and transmits a detection signal to controller 110. The oil temperature sensor 114 detects the temperature of the pressure oil,
The oil temperature signal is transmitted to controller 110. In addition,
The pressure sensor 112 and the oil temperature sensor 114 can be arranged in, for example, the shuttle valve 56, the pilot lines 36 and 38, and the tank 28, respectively.

When the pilot pressure is low, that is, when the turning hydraulic motor 14 is stopped, the controller 11
0, as shown in FIG. 7, the lower the oil temperature detected by the oil temperature sensor 114, the lower the current value supplied to the solenoid 108 of the supply / discharge control piece 106 within its allowable range, The opening degree of the supply / discharge control valve 106 is reduced. On the other hand, when the swing hydraulic motor 14 is driven and the pilot pressure rises and the sensor signal from the pressure sensor 112 increases, the controller 110 supplies the maximum supply current to the solenoid 108 of the supply / discharge control valve 116, The control valve 106 is completely switched to the supply position to maximize the valve opening.

[0032] Therefore, in the brake circuit device of FIG. 6, when stopping the hydraulic swing motor 14, the cylinder pressure of the brake releasing cylinder 70, i.e., adjusted set pressure P _S is in accordance with the oil temperature, the oil temperature be lower can be maintained set pressure P _S to be constant. This makes it possible to maintain the turning mechanical braking force and improve the responsiveness of releasing the braking when the turning hydraulic motor 14 is driven from a stopped state.

Further, a supply / discharge control valve 116 shown in FIG. 8 can be used instead of the supply / discharge control valve 80. The supply / discharge control valve 116 is a relief valve having a three-port two position. The supply / discharge control valve 116 has a supply position (h) for directly supplying oil pressure from the pilot oil pressure source 50 to the brake release cylinder 70 and a pressure chamber 72 of the brake release cylinder 70. And a discharge position (R) connected to the tank 28. The supply / discharge control valve 116 receives the biasing force of the return spring 118 on the supply position (h) side, can receive the pilot pressure from the communication pipe 86, and on the discharge position (h) side. Downstream pressure,
That is, the pressure in the pressure chamber 72 is received. That is, the pressure receiving portion on the discharge position (re) receives the pressure downstream of the supply / discharge control valve 116 as the relief pressure via the conduit 120. The supply / discharge control valve 116 is balanced between the supply position (h) and the discharge position (re) by the balance between the urging force of the return spring 118 and the relief pressure. Pressure oil is squeezed. Therefore, the same pressure reducing effect as in the case of the above-described diaphragm 82 is exhibited. In the above embodiment, an example has been described in which the braking of the turning hydraulic motor is released in response to the turning operation.However, in addition to the turning operation as shown in JP-A-4-44650, for example, a boom, The present invention is also applicable to a form in which the braking of the swing hydraulic motor is released in accordance with the operation of a working machine such as an arm or a bucket, that is, the operation of the front device.

[0034]

As described above, according to the brake circuit device for a swing hydraulic motor of the present invention (claims 1 and 2), when the swing hydraulic motor is braked by the brake device, the pressure chamber of the brake release cylinder. Is preliminarily pre-pressed, so that even when the pressure oil temperature is low, the responsiveness of the swing hydraulic motor to the release of braking can be improved, and as a result, damage to the brake device can be prevented and Smooth drive of the swing hydraulic motor is guaranteed.

If the preload to be applied to the pressure chamber of the brake release cylinder is adjusted to be constant based on the temperature of the pressure oil (claim 3), the responsiveness of the brake release can be improved while maintaining the braking force. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a hydraulic excavator.

FIG. 2 is a swing hydraulic circuit diagram including a supply / discharge circuit of a brake release cylinder.

FIG. 3 is a graph showing a rise response of a cylinder pressure in a brake release cylinder.

FIG. 4 is a graph showing a relationship between a cylinder pressure and a brake torque of a mechanical brake.

FIG. 5 is a diagram showing a brake circuit device according to a modification.

FIG. 6 is a diagram showing a part of a brake circuit device which is another modification.

FIG. 7 is a graph showing the relationship between the temperature of the pressure oil and the supply current supplied to the solenoid of the supply / discharge control valve.

FIG. 8 is a view showing still another supply / discharge control valve.

[Explanation of symbols]

 14 Rotating hydraulic motor 50 Pilot hydraulic source 54 Shuttle valve 68 Mechanical brake 70 Brake release cylinder 80 Supply / discharge control valve 86 Communication line 100 Supply / discharge control valve 110 Controller 112 Pressure sensor 114 Oil temperature sensor 116 Supply / discharge control valve

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeshi Nakamura 650, Kandamachi, Tsuchiura-shi, Ibaraki F-term in Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 2D003 AA01 AB02 BA08 CA03 DA03 DA04 DB02 DB06 3H089 AA90 BB15 BB21 CC08 DA02 DB04 DB46 DB49 EE07 EE13 EE14 EE17 EE22 GG02 JJ01

Claims (3)

[Claims] A brake release cylinder that mechanically brakes a turning hydraulic motor of a construction machine to release braking of the brake device by supplying pilot pressure; and a pilot pressure supplied to the brake release cylinder. A hydraulic pressure source, pilot pressure output means for controlling a flow of pilot pressure oil supplied from the hydraulic pressure source to the brake release cylinder at least in conjunction with driving of the swing hydraulic motor, the brake release cylinder and the hydraulic pressure source And a supply / discharge circuit for supplying and discharging pilot pressure oil to and from the brake release cylinder based on the operation of the pilot pressure output means. With the braking by the brake release cylinder, Brake circuit apparatus of a slewing hydraulic motor, characterized by comprising a preloading means for preloading the cylinder pressure to a predetermined set pressure. 2. The pressure supply device according to claim 1, wherein the preload application unit includes a pressure adjustment unit that adjusts a circuit pressure on the brake release cylinder side to the predetermined set pressure in the supply / discharge circuit.
6. A brake circuit device for a swing hydraulic motor according to claim 1. 3. The swing hydraulic motor according to claim 2, wherein the preload applying means further includes a variable means capable of adjusting the set pressure of the pressure adjusting means in accordance with the temperature of the hydraulic oil. Brake circuit device.