JPH03110225A - Controlling circuit for actuator in special vehicle - Google Patents

Abstract

PURPOSE:To make it possible to slowly change slowing speed of a slowing motor by connecting a plurality of actuators to a single hydraulic source respectively through a directional control valve and, at the same time, bleeding off the slowing directional control valve. CONSTITUTION:A variable capacity type pump 1 as a driving hydraulic source of a plurality of actuators and a pilot pump are started by a motor 3, and pressure oil is supplied to a directional control valve 10. After that, a control level L of a slowing direction change-over pilot valve 17 is controlled, and a spool of a pressure reducing valve 17A or 17B is controlled to send the oil pressure generating in either right or left of a pilot oil path 18 to the underside of the directional control valve 10 from a shuttle valve 19 through a pilot oil path 20. Then, in the midst of a stroke of the slowing directional control valve 12, a part of the pressure oil is immediately drained to an oil discharge path 15 by bleed-off action in the directional control valve 12.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a control circuit for an actuator in a special vehicle, particularly a swing motor for a rotating body in a power excavator, a boom elevating and/or telescopic cylinder, and a boom end. This invention relates to an actuator control circuit for a special vehicle in which a plurality of actuators, such as an arm cylinder for arm operation mounted on the arm and a packet cylinder for packet operation pivoted to the end of the arm, are each connected to a hydraulic power source via a directional control valve. .

(Prior Art) A rotating motor for a rotating body in a conventional power excavator, a cylinder for raising and lowering the boom and/or a telescopic cylinder, an arm cylinder for operating an arm attached to the end of the boom, and a packet cylinder for operating a packet attached to the end of the arm. An actuator control circuit for a special vehicle in which a plurality of actuators, such as Both types and types connected to multiple hydraulic power sources are known.

By the way, in a normal power excavator, the mass of the revolving body is quite large, and in order to ensure stable operability, the revolving body is normally operated quite gently. Although it is desired that the rotating speed of the rotating body does not change suddenly even when the control lever of the rotating body is operated somewhat roughly, that is, it has excellent turning operability (operation feeling), the rotating motor In contrast, other actuators require flow rate control that faithfully responds to the stroke amount of the operating lever of the directional valve (therefore, the spool of the directional valve).

For example, if the swing response of the swing body when operating the swing control lever of the swing motor during its stroke (half stroke) is based on the load sensing method, the swing speed of the swing motor will be determined by the stroke of the control lever (spool). However, if the bleed-off method is used, the response during the stroke will be considerably slower, but this slowdown in response, in other words, the slow turning of the rotating structure, It is believed that the speed change actually improves the operational sensitivity (operational feeling) of the swing motor.

By the way, there is a boom provided on the revolving body of a power shovel so that it can be raised and retracted, an arm attached to the end of the boom,
The operating cylinder, such as the packet at the end of the arm, is normally operated when the vehicle body of the excavator is vibrating, and as a result of this vehicle body vibration, the body of the operator of the excavator, The hand that grips the control lever also shakes, and as a result, when using the load sensing method, even during the stroke of the control lever, it faithfully responds to stroke changes, and the relief pressure of the hydraulic circuit, which is set at high pressure, Since the turning speed of the turning motor is changed quickly and sharply, its operability is reduced.

On the other hand, when adopting the bleed-off method, the control lever (
During the stroke of the actuator (spool), part of the pressure oil to the actuator is bled off by the bleed-off valve, and the hydraulic pressure after the bleed-off valve does not reach the relief pressure (high pressure) of the hydraulic circuit, so the swing motor Even if the swing response of the swing motor decreases, and even if the control lever is operated somewhat roughly, the swing speed of the swing motor will change gradually, allowing smooth transport of ready-mixed concrete packets, shovel work, etc.

(Problems to be Solved by the Invention) However, in the control circuit of the actuator including the swing motor in the conventional special vehicle as described above,
As a measure to gradually change the swing speed of a swing motor, a method in which multiple actuators are moved by a single hydraulic power source can reduce manufacturing costs by reducing the number of hydraulic power sources and reduce the installation space. On the other hand, in order to gradually change the rotation speed of this swing motor, it is necessary to operate the operating levers of other actuators after returning them to the neutral position, and after the swing operation of the swing motor is completed, the operation of the other actuators must be performed. There was a problem in that the operation became troublesome, such as the need to return the lever to its old position before starting the operation.

In addition, with two hydraulic power sources, the swing motor and other actuators, which require gradual speed changes, are driven by separate hydraulic power sources, regardless of the operating state of the other actuators. The swing speed of the swing motor can be changed gradually, and therefore the swing maneuverability of the power shovel can be improved, but on the other hand, two hydraulic power sources are required and the installation area increases, reducing the degree of freedom in design. At the same time, there was a problem of increased costs.

This invention was made by focusing on such problems in the conventional example, and it is possible to control a plurality of actuators including a swing motor of a swing body of a special vehicle by a single hydraulic pressure via a direction switching valve including a swing direction switching valve. and the swing direction switching valve is configured to perform a bleed-off function during the stroke of the spool, and between the swing direction switching valve and the hydraulic power source, pressure oil is supplied to the swing motor. An actuator for special vehicles that can solve the above-mentioned problems by providing a switching valve for switching supply/discharge and supply/discharge stop, and allowing pilot pressure for operating the turning direction switching valve to act on the switching valve. It is intended to provide a control circuit.

(Means for Solving the Problems) In order to solve the problems of the conventional examples as described above, the present invention provides a method for connecting a plurality of actuators including a swing motor of a swing body of a special vehicle to a direction switching valve including a swing direction switching valve. are connected to a single hydraulic power source via the spools, and the swivel direction switching valve is configured to perform a bleed-off function in the middle of the stroke of the spool, and the swivel direction switching valve is connected to a single hydraulic power source via the spool. A switching valve is provided for switching between supplying/discharging and stopping supply/discharge of pressure oil to the motor, and is configured such that a pilot pressure for operating the rotation direction switching valve can be applied to the switching valve.

(Function) Since the present invention has the above-described configuration, when operating various actuators in which each of the plurality of actuators of a special vehicle is connected to a single hydraulic power source via a directional control valve, the swing motor is Switching operation of the switching valve to supply/discharge and stop supply/discharge of pressure oil.

By switching the swing direction switching valve of the swing motor and the switching operation of the swing direction switching Parrot valve, the pilot pressure is used to simultaneously operate the swing direction switching valve, regardless of the operation of other actuators, and the swing direction switching valve has a full stroke. bleed off a part of the pressure oil supplied to the swing motor during the swing of the swing motor at a specified speed and during the stroke of the swing direction switching valve, that is, during the stroke other than the neutral and full stroke of the spool; During the stroke of the operating lever (spool) of the swing direction switching valve, the speed of the swing motor is changed gently regardless of the rough operation.

(Example) Hereinafter, an example of a control circuit for an actuator in a special vehicle according to the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a variable displacement pump as a hydraulic pressure source for driving various actuators of a power shovel (not shown); 2 indicates a switching valve for a control circuit of the various actuators;
A pilot pump for generating pilot pressure in a control oil passage that controls the operating status of various operation valves including (swivel) directional control valves;
Reference numeral 3 denotes an electric motor as a turbulence prime mover for the variable displacement pump 1 and the pilot pump 2 (this electric motor may also be an engine), 4 a tank, and 5 a variable displacement pump 3.
control section, 6 is a pressure oil passage for operating various actuators, 7 is
．． 7 is a flow control valve, 8.8 is a check valve, 10 is a switching valve for switching between supplying and discharging pressurized oil to the swing motor 14 and stopping the supply and discharging, IIA is an oil supply path, and 11B is an oil drain path.

Reference numeral 12 denotes a rotation direction switching valve, and the rotation direction switching valve 12 is operated during switching from the neutral position of the spool to the full stroke (
It is configured to perform a bleed-off function during the half stroke. 13 is a pressure oil supply/discharge path to the swing motor 14; 16 is a pilot pressure oil path for switching the direction switching valves of various actuators; and 17 is the swing direction switching valve 12 which is switched by tilting the lever L left or right. The pilot valve 17 for switching the turning direction is a pilot valve for switching the turning direction to move the left and right right and left pressure reducing valves 17A,
17B, for example, move the lever L to the left L.
By tilting to A, the spool of the left pressure reducing valve 17A is pushed down, the pressure oil of the pilot pump 2 is reduced, and the rotation direction switching valve 1 is operated via the pilot oil passage 18 (left side).
2 to the right side and discharge it to the tank 4 via the pilot pressure oil supply/discharge path 18 (right side) on the right side of the quantity valve 12 and the right side 17B of the pilot valve 17 for switching direction of rotation.

19 is a shuttle valve installed between the left and right pilot oil passages 18.18, and lever L allows either the left or right pressure reducing valve 17A,
When the spool of 17B is operated, the pilot oil path 1
Pilot pressure oil generated on either the left or right side of the shuttle valve 19 is transferred to the switching valve 10 via the pilot oil passage 2o.
The switching valve 10 is raised to feed pressure oil from the variable displacement pump 1 to the swing direction switching valve 12 side (as shown in the figure).

Note that when the operating lever L of the pilot valve 17 is in the neutral state, no pilot pressure is generated in either the left or right pilot oil passages 18.18, so no pilot pressure is generated in the pilot oil passage 20 from the shuttle valve 19, and this In this case, the switching valve 10 enters the illustrated pressure oil supply/discharge state.

Reference numeral 21 denotes a direction switching valve that switches the direction of supply and discharge of pressure oil to and from the arm cylinder 23 via the supply and discharge passage 22, and the arm cylinder 23 has its base pivoted on a revolving body on the vehicle body frame (not shown). , reciprocates a packet manipulation arm provided at the end of the boom that can be raised and retracted. 24
is a shuttle valve that senses oil pressure fluctuations in the pressure oil (after throttling) within the directional control valve 21. The output C of this shuttle valve 24 is sent to the control device 5, which controls the discharge of the variable displacement pump 1. The capacity is adjusted to rA.

Although not shown in the drawings, actuators such as the lifting and retracting cylinder of the boom that can be raised and retracted and the packet cylinder that swings the packet at the end of the arm are also used to supply pressure oil to the flow rate control valve 7 and the arm cylinder 23. A flow rate control valve, a pressure oil supply/discharge direction switching valve, a shuttle valve, etc. having substantially the same structure as the exhaust direction switching valve 21, shuttle valve 24, etc. is provided between the pressurized oil passage 6 and the oil drainage passage 15, It is arranged in parallel with the directional switching valve 21 and the like, but these are provided inside the valve block B.

Next, the operation of this example is demolded.

First, the variable displacement pump 1 and the pilot pump 2 are started by the electric motor 3, and the pressure oil line 6, the flow rate control valve 7. Pressure oil is sent to the switching valve 10 via the check valve 8 and the like. On the other hand, when the operating lever L of the swing direction switching number pilot valve 17 is moved from its neutral position (solid line position) to the left, for example, to the dashed-dotted line position LA, the spool of the left pressure reducing valve 17A is lowered, and the pilot pump 2 pilot pressure oil is in oil passage 16
, acts on the left side of the spool of the swing direction switching valve 12 via the left pressure reducing valve 17A and the left pilot oil passage 18,
The right side is connected to the tank 4 via the right pilot oil passage 18 and the right pressure reducing valve 17B, and moves the spool of the rotation direction switching valve 12 to the right.

At the same time, a part of the pressure oil in the left pilot oil passage 18 is sent to the lower side of the switching valve 1o via the shuttle valve 19 and the pilot oil passage 20, and the spool of the switching valve 10 rises to increase the pressure. The oil supply/discharge position is reached, and the pressure oil in the pressure oil path 6 is sent to the swing direction switching valve 12 via the flow rate control valve 7, check valve 8, switching valve 10, and pressure path 11A, and the same swing direction is switched. An amount of pressure oil corresponding to the spool stroke of the valve 12 is supplied to the supply/discharge path 13 (right side), the swing motor 14, and the supply/discharge path 13 (left side).
, turning direction switching valve 12, oil drain path 11B, switching valve 10. The oil is discharged to the tank 4 via the drain passage 15, and
For example, turn to the right.

The pressure oil supply/discharge position, which moves to the upper side of the spool of the switching valve 10, can be adjusted by tilting the control lever L of the rotation direction switching valve 17 to the right (not shown) and moving the spool of the right pressure reducing valve 17B. This is also ensured in the same way as above when lowering.

In addition, during the stroke of the rotation direction switching valve 12 to the right, a part of the pressure oil in the pressure oil passage (the oil passage from the lower left to the upper right in the figure) is transferred to the drainage oil passage of the switching valve 12. (Bleed-off) to the (oil path running from the top left to the bottom right in the diagram)
However, since the amount of pressure oil sent to the swing motor 14 decreases,
The change in the turning speed of the turning motor 14 is correspondingly reduced to the minimum.

Therefore, during the stroke of the spool of the rotation direction switching valve 12, if the hand of the operator who grips and operates the operating lever L is slightly oscillated, the rotation direction switching valve 12 may be moved through the pilot oil passage 18. Even if the spool moves back and forth little by little, due to the bleed-off effect within the switching valve 12, a portion of the pressure oil that should be directed to the swing motor 14 is
The oil immediately flows out to the drain path 15 side, thereby avoiding a rapid speed change of the swing motor 14 and improving its swing operability (feeling).

If the operating lever L is tilted further, the spool of the turning direction switching valve 12 moves further to the right, reaching a full stroke, and in this state, the turning direction switching valve 1
The bleed-off effect within the stroke motor 2 disappears, and the swing motor 14 swings in the same direction as above at a predetermined speed, which is faster than during the stroke.

Next, when the operating lever L is raised, the swing direction switching valve 12 returns to the neutral position in the middle of the stroke (on the right side).

When the operating lever L is pushed further to the right beyond this neutral position, the spool of the right pressure reducing valve 17B of the pilot valve 17 is lowered, and the swing direction switching valve 12 is moved to the left side full stroke through the left stroke midway position. In each state, the operation is substantially the same as that described above, and the turning motor 14 is turned to the left in the opposite direction to that described above.

Therefore, by tilting the operating lever L of the pilot valve 17 for switching direction of rotation to either the left or right, the pressure reducing valve 17A of either the left or right
, 17B, when the spool of the turning direction switching valve 12 is advanced to either the left or right full stroke through its intermediate stroke, in the middle of the stroke, that is, the operating lever L is moved to its neutral position. In the intermediate range between the maximum tilt angle and the maximum tilt angle, even if the operating lever L is operated somewhat roughly, the rotation speed of the rotating body of the power excavator will change gradually, and the power shovel will not move smoothly. Swivel operation is performed.

Although not shown, the present invention also applies to a power excavator in which some actuators other than the swing motor in the embodiment described above, such as the arm cylinder 23, its direction switching valve 21, and the flow rate adjustment valve 7, are omitted. It can be implemented as is without changing the rest of the configuration.

Although not shown in the drawings, the present invention also provides a telescoping boom that is capable of raising and lowering and extending and retracting provided on the revolving body, a packet provided via an arm at the end of the telescoping boom, an operating cylinder thereof, a directional switching valve, etc. , a truck crane that has a boom that can be raised and retracted on a revolving body and suspends the load with a hook at the lower end of a rope hanging from the end of the boom.
The actuator control circuit for multiple actuators, such as a motor for moving a rotating body of a truck crane, which is equipped with an operating cylinder and a directional control valve for a hoisting and telescoping boom, also has a stroke By providing a swing direction switching valve that performs a bleed-off action only midway, it can be carried out without changing the rest of the hydraulic circuit configuration. Even if the same lever is operated somewhat roughly, the turning speed of the rotating body changes gradually, and the same improvement in turning operability as described above can be expected.

Note that the switching valve 10 that switches between supplying and discharging pressure oil to the swing direction switching valve 12 and stopping the supply and discharging in the present invention has its supply and discharging stop side, that is, the connection side between the oil drain path 11B and the oil drain path 15. , it is also possible to configure it as a communicating structure (not shown) without being interrupted as in the illustrated example.

(Effects of the Invention) Since the present invention has the above-mentioned configuration and performs one action,
The following effects can be obtained.

(1) A plurality of actuators including a swing motor of a swing body of a special vehicle are each connected to a single hydraulic power source via a directional control valve, and a mechanism is connected between the swing motor and the hydraulic power source to the same swing motor. a switching valve for supplying and discharging pressurized oil and stopping the supply and discharging of the pressure oil, and a swing direction switching valve for the swing motor, and
Since the switching valve and the swing direction switching valve are controlled simultaneously by the pilot pressure of the swing direction switching pilot valve, the switching operation of the swing direction switching pilot valve is sufficient, regardless of the operating state of other actuators. Can control the swing motor.

(2) Since the directional control valve to the swing motor is designed to bleed off part of the pressure oil during its stroke, the spool (control lever) of the swing direction control valve does not bleed off during the stroke. A part of the pressure oil to the motor is bled off, and the ability of the swing motor to follow the operating lever is reduced, improving the feel of the swing operation, and furthermore, other actuators can be operated without any hindrance.

(3) Even if the operating lever of the swing motor is operated somewhat roughly due to vibrations of the body of the special vehicle, vibrations of the body of the operator of the special vehicle, or vibrations of the gripping arm of the operating lever of the swing motor, the swing motor may not operate properly. Since there is no fear of inadvertently changing the rotational speed, the operability is improved.

(4) No hydraulic power source dedicated to the swing motor is required;
The installation space for the hydraulic power source can be saved, and the degree of freedom in designing it can be improved, leading to cost reductions.

(5) A switching valve for supplying and discharging pressure oil and stopping the supply and discharging of pressure oil is provided between the swing direction switching valve for the swing motor in the conventional similar device and the hydraulic power source, and the switching valve and the switching valve The present invention can be carried out by a structural change that allows the shuttle valve material to be adjusted simultaneously by a pilot valve for switching the rotation direction.

[Brief explanation of drawings]

The drawing is an explanatory diagram of an embodiment of an actuator control circuit in a special vehicle according to the present invention. 1...Variable displacement pump, 2...Pilot pump, 4...Tank, 7...Flow rate control valve, 1o...Switching valve , 12...
...Swivel direction switching, 14...Swivel motor, 16...Pilot pressure oil path, 17A, 17B...Pressure reducing valve,

Claims (4)

[Claims] (1) A plurality of actuators including a swing motor of a swing body of a special vehicle are each connected to a single hydraulic power source via a directional switching valve including a swing direction switching valve, and the swing direction switching valve strokes the spool. A switching valve is provided between the swing direction switching valve and the hydraulic power source, and is configured to perform a bleed-off function in the middle of the swing motor, and is configured to switch between supplying and discharging pressure oil to the swing motor and stopping the supply and discharge of pressure oil. A control circuit for an actuator in a special vehicle, characterized in that a pilot pressure for operating the turning direction switching valve can be applied. (2) A plurality of actuators including the swing motor of the swing structure of the special vehicle are each connected to a single hydraulic power source via a directional switching valve including a swing direction switching valve, and the swing direction switching valve and the hydraulic power source are connected to each other via a directional switching valve including a swing direction switching valve. A switching valve for switching between supplying and discharging pressure oil to the swing motor and stopping the supply and discharge of pressure oil is provided between the swing motors, and a pilot pressure for operating the spool of the swing direction switching valve is simultaneously applied to the spool of the switch valve, thereby controlling the swing direction. 2. The actuator control circuit for a special vehicle according to claim 1, wherein the switching valve is switched to a pressure oil supply/discharge position when a spool of the switching valve is in a non-neutral position. (3) A claim characterized in that the pilot valve for switching the swing direction that generates pilot pressure to the spool of the swing direction switching valve is constituted by a pair of left and right pressure reducing valves that are alternately operated by the operating lever thereof. A control circuit for an actuator in a special vehicle according to item (2). (4) The output pilot pressure of the pair of left and right pressure reducing valves of the swing direction switching pilot valve is applied to both ends of the spool of the swing direction switching valve, and the output pilot oil passages of both pressure reducing valves are controlled by a shuttle valve. Claim (3) characterized in that the switching valve is connected to the switching valve, and the output pilot pressure of the shuttle valve is applied to the spool end of the switching valve.
A control circuit for an actuator in the special vehicle described.