JP2816994B2 - Control valve for hydraulic circuit for special vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a control valve for a hydraulic circuit for a special vehicle, in particular, a swing motor for a hydraulic circuit for a special vehicle such as a truck crane, a power shovel, etc .; Or, a controller for a special vehicle hydraulic circuit suitable for driving a turning motor in a hydraulic circuit that drives a plurality of actuators such as a telescopic cylinder, a bucket operating arm cylinder mounted on the end of a boom, and a traveling motor by a single hydraulic source. For valves.

(Prior Art) Conventionally, a plurality of actuators such as a swing motor of a hydraulic circuit for a special vehicle such as a truck crane and a power shovel, an up-and-down and / or telescopic cylinder of a boom, and a bucket operating arm cylinder mounted on a tip of the boom are connected to a hydraulic power source. Although not shown, the control valve of the hydraulic circuit for a special vehicle driven by a swing motor of a revolving body on a body frame, an up-and-down cylinder of an up-and-down boom having a base mounted on the revolving body, a telescopic cylinder, and a A plurality of actuators such as arm cylinders for swinging the bucket attached to the shaft are connected to one or two hydraulic sources via respective control valves, and crane work and power shovel work are performed by operating each control valve. And the like are known.

In addition, the revolving structure of the crane needs to be revolved with the load suspended on the hook at the lower end of the rope that hangs from the tip of the boom that can be raised and contracted. In addition, it is necessary to suppress the sudden change in speed, and to prevent sudden changes in the so-called turning feeling.
Since the revolving structure needs to be revolved during the excavation work by the bucket, the revolving operation of the revolving structure needs to be adjusted at a considerably slow speed.

Further, the actuator of the hydraulic circuit for a special vehicle is normally operated by one of a load sensing method and a bleed-off method. When the followability of the body is based on the load sensing method, the swing speed of the revolving body follows the operation lever stroke quite faithfully, whereas when using the bleed-off method, the responsiveness is considerably slowed down. But
It is also known that such a slowing of the followability of the revolving structure smoothes the speed change and improves the operation sensitivity (so-called operation feeling).

(Problems to be Solved by the Invention) However, in a conventional control valve of a hydraulic circuit for a special vehicle, for example, a boom of a power shovel,
When operating an arm or the like, the body of the operator or the hand holding the lever also shakes with the occurrence of shaking of the vehicle body, and when the load sensing method is adopted, even when the operation lever is half-operated, There has been a problem that the hydraulic pressure of the circuit set to a high pressure (relief pressure) acts on the swing motor as it is, and even a slight change in the operating lever angle causes a considerable change in the swing speed, which impairs the driving operability.

On the other hand, in the case of adopting the conventional blue-off method,
At the half-control position of the operating lever, the hydraulic oil in the hydraulic circuit bleeds off and does not reach the relief pressure (maximum pressure) of the circuit, so the change in the turning speed of the turning motor becomes gentle with respect to the change in the operating lever angle. Therefore, even if the operation lever is operated slightly rough, the rotation speed of the swing motor can be adjusted smoothly, and crane work and bucket transport of ready-mixed concrete can be performed smoothly. There is a problem that it is necessary to make the actuator and the actuator separable, and to switch the two.

Further, in the case where a plurality of actuators are driven by one hydraulic power source, the installation space of the hydraulic power source can be reduced, and the manufacturing cost is reduced, but the fine adjustment of the rotation motor speed is not easy. there were.

Further, in the case of using two hydraulic power sources, the hydraulic power sources for the swing motor and the other actuators can be separately adjusted, so that each can be adjusted particularly. In particular, fine adjustment of the swing motor speed becomes easy. Although it is easy to obtain a hydraulic circuit configuration that can improve the operability of cranes and power shovels, there is a problem that not only two hydraulic power sources are required, but also the installation space is increased and the cost is increased. Was.

The present invention has been made in view of such a problem in the conventional example, and by using a normal load sensing system and providing a notch that acts to bleed off only during the stroke of the control valve, It is an object of the present invention to provide a control valve of a hydraulic circuit for a special vehicle, which can solve such a problem.

(Means for Solving the Problems) In order to solve the problems of the conventional example as described above, the present invention provides a high-pressure oil path connected to a hydraulic power source, a hydraulic oil path connected to a hydraulic motor, and a tank. A spool having a large-diameter portion and a small-diameter portion is slidably mounted on a valve body having an oil drain connected thereto, and the high-pressure oil passage, the hydraulic oil passage,
A bleed-off valve that operates only during the stroke of the spool is provided between the oil discharge passage and the spool.

(Operation) Since the present invention has the above-described configuration, the hydraulic fluid for the turning motor in the hydraulic circuit for a special vehicle in which a plurality of actuators are provided between the control valve and a tank of one hydraulic power source. In addition to acting as a normal control valve by using it as a control valve, it also bleeds off a part of the high-pressure oil in the high-pressure oil passage or hydraulic oil passage by moving the spool in the middle of the stroke, and sends it to the swing motor. And the change in the turning speed of the turning motor is gently adjusted.

(Embodiment) Hereinafter, an embodiment of a control valve of a hydraulic circuit for a special vehicle according to the present invention will be described with reference to the drawings.

(First Embodiment) FIGS. 1 and 2 are longitudinal sectional views of a spool according to a first embodiment of the present invention in a state where the spool is neutral and in the middle of a stroke, and FIG. 7 is an explanatory view of its operation.

In the figure, reference numeral 1 denotes a valve body of a control valve 1a. The control valve 1a is a pump 15 as a hydraulic power source for a special vehicle such as a power shovel or a crane (not shown).
(See FIG. 7) and a swing motor 16 (see FIG. 7) of a swing body on the body frame.

2 is a spool hole provided in the center of the valve body 1, 3 is a high-pressure oil passage, 4 is a working oil passage, 5 is a drain oil passage, and 6 is a working oil passage 4.
7 is a check valve, 8 is a spool, 9 and 10 are large and small diameter portions of the spool 8, 11 is a notch constituting a bleed-off valve, and the notch 11 is a spool 8 Is formed in the large-diameter portion 9 so as to extend in the direction of its length (left and right in FIG. 1). t is the tank, m is the thickness of the partition wall 6 in the length of the spool 8 (left and right in FIG. 1), n is the length of the notch 11 in the length of the spool 8 (left and right in the drawing),
This length n is configured to be slightly longer than the thickness m of the partition wall 6.

 Next, the operation of this embodiment will be described.

In the neutral state (FIG. 1) of the control valve 1a, the pump port P, the tank port T, the A and B ports of the hydraulic oil passages 4, 4 are connected to the left and right and central large diameter portions 9, 9 of the spool 8. Both are closed by the partition walls 6, 6 of the valve body 1, and in this state, the turning motor 16 stops.

From the state of FIG. 1, slightly push the operation lever L to the left,
When the spool 8 is in the middle of the stroke shown in FIG.
15 pressure oils are check valve 7, high pressure oil passage 3, spool 8
Through the small-diameter portion 10 to the right-hand hydraulic oil passage 4, and from the A port to the left-side oil drain passage 5 through the swing motor 16, the B port, the left-hand hydraulic oil passage 4, and the left-hand small-diameter portion 10 of the spool 8, After being discharged from the T port to the tank t, the swivel motor 16 (therefore, the swivel body on the body frame not shown) is rotated at a speed corresponding to the stroke of the spool 8.
The operation itself is substantially the same as that of a conventional control valve of this type of special vehicle hydraulic circuit.

However, in this embodiment, the control valve 1a
In the middle of the stroke of the spool 8 (FIG. 2), a part of the pressure oil in the right hydraulic oil passage 4 is subjected to a throttling action corresponding to the size of the right notch 11, so that the right oil drain 5 To the tank t (see FIG. 6) via the T port,
The rotation speed of the swing motor 16 gradually changes according to the size of the notch 11 and the minimum opening degree between the notch 11 and the working oil passage 4 or the drain oil passage 5.

Next, if necessary, the spool 8 is further pushed to the left from the middle of the stroke in FIG. 2 so that the right side of the right notch 11 separates from the right discharge oil passage 5 and the pressure oil in the right working oil passage 4 The outflow to the right discharge oil passage 5 through the notch 11, that is, the bleed-off action is prevented, and the total pressure oil in the high pressure oil passage 3 is sent to the swing motor 16 via the right hydraulic oil passage 4, and the left hydraulic oil is It is discharged to the tank t via the path 4, the left small-diameter portion 10, the left discharge oil path 5, and the T port, and drives the swing motor 16 at a predetermined high speed.

After the revolving body is rotated by a predetermined angle by the revolving motor 16, the spool 8 is returned to the neutral position in FIG. 1 through the middle of the left stroke in FIG.

When the spool 8 is pulled to the right opposite to that in FIG. 2, the pressure oil in the high-pressure oil passage 3 is sent to the turning motor 16 through the small-diameter portion 10 on the left side of the spool 8 and the left-hand working oil passage 4, The oil is discharged to the tank t via the right working oil passage 4, the right small-diameter portion 10, the right oil discharge passage 5, the T port, and the like, and the turning motor 16 is turned in the opposite direction. A part of the pressure oil in the left working oil passage 4 flows out to the left discharge oil passage 5 through the left notch 11 (bleed-off) during the stroke of, and the turning motor 16 is decelerated in the same manner as described above. ,
Shift slowly.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. Parts common to those in the first embodiment shown in FIGS. 1, 2, and 7 are denoted by the same names and the same reference numerals.

In the figure, reference numeral 1 denotes a valve body of a control valve 1b, which is a pump 15 (FIG. 8) as a hydraulic source of a special vehicle such as a power shovel or a crane (not shown), and a turning motor 16 ( FIG. 2 is a spool hole at the center of the valve body 1,
3 is a high-pressure oil passage, 4 is a working oil passage, 5 is a drain oil passage, 6 and 6 are partition walls between the high-pressure oil passages 3 and 3 and the working oil passages 4 and 4, and m is a spool 8 of the partition walls 6 and 6. The thickness in the length direction, 7, 7 is a check valve, 9 and 10, 10 are a central large diameter portion and a small diameter portion of the spool 8, and 11 is a shaft ( A notch 11 is provided as a bleed-off valve recessed in the left-right direction in FIG. 3. The notch 11 has a notch provided in the axial direction (left-right direction in FIG. 3). The partition walls 7, 7 are configured to be slightly longer than the thickness m.

 Next, the operation of this embodiment will be described.

In the neutral state of the control valve 1 (FIG. 3), the pump port P, the tank port T, the hydraulic oil passages 4, 4
Ports A and B are closed by the large-diameter portion 9 of the spool 9, and the turning motor 16 stops. In this state, when the operation lever L is slightly pushed to the left and the spool 8 is in the middle of the stroke shown in FIG. 4, the pressure oil of the pump 15 passes through the check valve 7, the high-pressure oil passage 3, and the right-side small-diameter portion 10 of the spool 8. Proceed to the right hydraulic oil passage 4 and proceed to the left oil drain passage 5 via the A port, the swing motor 16, the B port, the left hydraulic oil passage 4, the left small diameter portion 10 of the spool 8, and the tank via the T port. t
(FIG. 8), the swivel motor 16 and, therefore, the revolving body (not shown) are tentatively driven at a speed corresponding to the stroke of moving the spool 8 to the left. Has almost the same effect.

However, in this embodiment, in the middle of the stroke shown in FIG. 4, a part of the pressure oil in the left high-pressure oil passage 3 passes through the left notch 11 and is subjected to a throttling action in accordance with the size of the notch 11, and As shown by a broken line in the drawing, the oil flows out to the left oil drain passage 5 through the hydraulic oil passage 4 and the small diameter portion 10 on the left side, and is bleed off. Alternatively, deceleration driving corresponding to the minimum opening degree with the working oil passage 4 is performed, and the swing motor 16 shifts slowly.

Next, when the spool 8 is further pushed to the left from the middle of the stroke shown in FIG. 4, the right side of the left notch 11 is cut off from the left pressure oil passage 3, and the hydraulic oil to the left working oil passage 4 through the notch 11 Outflow (bleed-off) is prevented. In this case, the entire pressure oil in the high pressure oil passage 3
Through the left working oil passage 4, the left small diameter portion 11, the left oil discharge passage 5, and the tank t via the T port.
And the turning motor 16 is driven at a predetermined high speed.

After the revolving body is rotated by a predetermined angle by the revolving motor 16, the spool 8 is returned to the neutral state in FIG. 3 through the middle of the left stroke in FIG.

If the spool 8 is moved rightward, contrary to FIG. 4, the pressure oil in the high-pressure oil passage 3 is supplied to the turning motor 16 via the left-hand small-diameter portion 10 of the spool 8 and the left-hand working oil passage 4. Then, the fluid is discharged to the tank t via the right working oil passage 4, the right small diameter portion 10, the right oil discharge passage 5, the T port and the like, and the turning motor 16 is turned in the opposite direction. At this time, in the middle of the stroke of the spool 8 to the right, a part of the pressure oil in the right working oil passage 4 flows out to the right working oil passage 4 via the right notch 11 and is bleed off. It is discharged to the tank t via the T port, the swing motor 16 is driven at a low speed, and its speed changes slowly.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. In addition, the second shown in FIGS.
The same names and the same reference numerals are used for the portions common to the embodiment.

In the figure, reference numeral 1 denotes a valve body of a control valve 1c, which is a pump 15 (FIG. 9) as a hydraulic source of a special vehicle such as a power shovel or a crane (not shown) and a swing motor 16 of a swing body on a body frame (not shown). ). 2 is a spool hole in the center of the valve body 1, 3 is a high-pressure oil passage, 4 is a hydraulic oil passage, 5 is a drain oil passage, and 6, 6 are partitions between the high-pressure oil passages 3, 3 and the hydraulic oil passages 4, 4. Wall, m is partition wall 6, 6
Thickness of the spool 50 in the longitudinal direction, 7, 7 is a check valve,
51 is a sleeve of the spool 50 slidably inserted into the spool hole 2, 52 is a stepped hole of the sleeve 51, 53 is a notch as a bleed-off valve provided in a large diameter portion of the sleeve 51, and the notch 53 is A concave portion is provided at a contact portion between the large-diameter portion and the partition wall 6, and extends in the length direction thereof.

54 is a small diameter portion of the sleeve 51, 55 and 56 are provided at the center portion and both side portions of the sleeve 51, communicate the inside and outside thereof, and are communication holes for pilot pressure, and the communication holes 56 are two small diameter holes each. Is configured as Although not shown, the communication holes 56 may be configured as individual holes.

58 is a spool body inserted in the sleeve 51, 59 is a protrusion with a hollow hole of the spool body 58, 60 is a check valve with a spring, 61
Is an annular groove, and the annular groove 61 communicates with the hollow hole of the protrusion 59. n is the length of the notch 53 in the length direction of the sleeve 51, and the length n is slightly longer than the thickness m of the partition walls 7,7.

 Next, the operation of this embodiment will be described.

In the neutral state (FIG. 5) of the control valve 1c, the pump port P, the tank port T, the hydraulic oil passages 4, 4
All of the ports A and B are closed by the large diameter portion of the sleeve 51 around the spool 50, and the turning motor 16 stops.

When the operating lever L is slightly pulled to the right and the spool 50 is slightly moved to the right, and in the middle of the stroke shown in FIG.
The pressure oil of the pump 15 (FIG. 9) advances to the right side of the left check valve 60 through the check valve 7, the high-pressure oil passage 3, and the communication hole 55 at the center of the left side of the sleeve 51, and the spring-equipped check valve 60 of the spool 50. Is retracted to the left against the spring, and the high pressure oil passage 3
From the left hydraulic oil passage 4 as shown by the solid line with the arrow in the same figure, through the B port, the swing motor 16 (same figure), the A port, the right hydraulic oil passage 4, and the right small diameter portion 54 of the sleeve 51. Proceeds to the right oil drain 5 and discharges to the tank t (shown in the figure) through the T port, and the swing motor 16 and therefore the swing body (not shown)
An attempt is made to drive the spool 50 at a speed corresponding to the displacement during the stroke to the right.

However, in this embodiment, during the stroke of the spool 50 (FIG. 6), a part of the pressure oil in the left high-pressure oil passage 3 is transferred from the right high-pressure oil passage 3 as indicated by a broken line with an arrow in FIG. Flows through the right notch 53 into the right hydraulic oil passage 4, receives a throttling action (bleed off) according to the size of the notch 53, and is discharged into the right hydraulic oil passage 4.
The oil is discharged to the right discharge passage 5 through the right small-diameter portion 54 of the spool 50 together with the oil discharged from the revolving pump 16.

Accordingly, the swing motor 16 is driven at a reduced speed corresponding to the size of the notch 53 and the minimum opening degree between the notch 53 and the high-pressure oil passage 3 or the working oil passages 4, 4. Shift to

The remaining operation of this embodiment is substantially the same as that of the second embodiment.

Further, the control valve of the present invention can be applied as it is as a control valve of a hydraulic circuit for a traveling hydraulic motor of a special vehicle, and in particular, an operation lever for controlling a traveling hydraulic motor at a work site or the like is provided with an operating lever. When operating in the middle of the stroke, even if the driver's hand gripping the operation lever is slightly blurred, the supply and discharge amount of pressure oil to the traveling motor changes gradually,
The traveling speed is adjusted slowly.

(Effects of the Invention) The present invention has the above-described configuration and operates, and the following effects can be obtained.

(1) Since the control valve has a bleed-off valve that operates only in the middle of the stroke of the spool, other types of actuators for special vehicles such as power shovels and cranes are driven by a single hydraulic power source. By providing this control valve for the swing motor of the hydraulic circuit without changing the configuration, it is easy to obtain a configuration in which the amount of pressurized oil supplied to the swing motor is gradually changed in the middle of the stroke of the oil spool. Can be

(2) Since there is no need to provide a hydraulic source dedicated to the swing motor, the installation space for the hydraulic source can be reduced, and the cost of the control valve of the hydraulic device for special vehicles and the hydraulic circuit using the control valve can be reduced. I can measure.

(3) By using this control valve as a control valve of a turning motor in a hydraulic circuit for a special vehicle in which a plurality of actuators are driven by the same hydraulic source, the control valve for a special vehicle can be used without changing the control valve structure for other actuators. A hydraulic circuit can be configured.

(4) By using this control valve for the turning motor in the hydraulic circuit for the special vehicle for sampling the pump load sensing system, the hydraulic circuit configuration for other actuators in the existing hydraulic circuit for the special vehicle can be changed. , Can be applied as is.

(5) Since it is not necessary to turn off the flow control valve of the hydraulic circuit, the rotation speed of the swing motor can be smoothly controlled regardless of the operation state of other actuators.

(6) Even if the control lever of the control valve for a hydraulic motor such as a swing motor or a travel motor is operated somewhat rough, the supply / discharge amount of pressure oil to the hydraulic motor such as the swing motor or the travel motor changes rapidly. Since there is no danger of turning, the turning operation of the turning body of the special vehicle or the simplification of the hydraulic circuit configuration for the traveling motor can be achieved.

(7) If notches are formed on both sides of the central large-diameter portion of the spool, when the B or A port and the P port communicate with each other in the middle of the stroke of the spool, the check valve always operates on either side of each notch. Can also be prevented from flowing backward, so if the holding pressure of the revolving
Alternatively, regardless of which side of the A port is actuated, the respective holding pressures are locked, and there is no danger of generating a tilt flow due to the tilt of the rotating body.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of a control valve of a hydraulic circuit for a special vehicle according to the present invention. FIG. 1 is a longitudinal sectional view in which the spool of the control valve of the first embodiment is in a neutral state, and FIG. FIG. 3 is a longitudinal sectional view showing a state in the middle of a stroke in which the spool is slightly moved to the left, and FIG.
FIG. 4 is a longitudinal sectional view of the control valve of the embodiment in a neutral state, FIG. 4 is a longitudinal sectional view of the middle of a stroke in which the spool is slightly moved to the left, and FIG. 5 is a control of the third embodiment. FIG. 6 is a vertical cross-sectional view of the control valve of the first to third embodiments in which the spool of the valve is in a neutral state, FIG. It is an operation explanatory view. 1a, 1b, 1c ... control valve, 1 ... control valve body, 3, 3 ... high-pressure oil path, 4, 4 ... working oil path, 5, 5 ... oil discharge path, 6 ... partition wall, 7, Check valve, 8, 50 Spool, 9, 9 Large diameter section, 10, 10 Small diameter section, 11, 11, 53, 53 Notch, 15 Pump (hydraulic source), 16: Rotating motor, 51: Sleeve, 54: Small diameter part, 56: Communication hole, 58: Spool body, 59: Hollow protrusion, 60: Check valve with spring, m: Between oil passages Wall thickness, n ... length of notch.

Claims (5)

(57) [Claims] A large-diameter portion and a small-diameter portion are provided in a valve body having a high-pressure oil passage connected to a hydraulic pressure source, a working oil passage connected to a hydraulic motor, and a drain oil passage connected to a tank. A spool is slidably mounted, and a bleed-off valve that operates only during the stroke of the spool is provided between the high-pressure oil passage, the working oil passage, and the drain passage and the spool. Control valve for oil circuit for special vehicles. 2. A large-diameter portion of the spool is provided with a pair of left and right notches, and a length of the notch in a spool length direction is set to a spool length of a partition wall of the road adjacent to and adjacent to the large-diameter portion of the spool. 3. The control valve according to claim 1, wherein the control valve is configured to be slightly longer than the thickness in the direction. 3. A notch is provided in each of the large-diameter portions on both sides of the spool, and the length of the notch in the length direction of the spool is partitioned between a hydraulic oil passage and an oil-discharge passage of the valve body that abuts the large-diameter portions on both sides. 3. The control valve according to claim 2, wherein the thickness of the wall is slightly longer than a thickness of the wall in a spool length direction. 4. A notch is provided on each side of a large diameter portion at the center of the spool, and a length of the notch in a spool length direction is set between a high pressure oil passage and a working oil passage of the valve body which abuts the center large diameter portion. The control valve for a hydraulic circuit for a special vehicle according to claim 2, wherein the partition wall is configured to be slightly longer than a thickness in a spool length direction. 5. A high-pressure oil passage 3 connected to a hydraulic pressure source 15, working oil passages 4 and 4 connected to a hydraulic motor such as a swing motor 16 or a traveling motor, and a drain oil passage 5 connected to a tank t. A spool 50 composed of a sleeve 51 and a spool body 56 is slidably mounted in a spool hole 2 of a valve body 1 having a notch on both sides of a central large-diameter portion of the sleeve 51.
The length m of the notches 53, 53 is set to the high pressure oil passages 3, 3 of the valve body 1 which abuts on the large diameter portion of the sleeve 51.
The sleeve 51 of the partition wall 6, 6 between the
A control valve for a hydraulic circuit for a special vehicle, wherein the control valve is configured to be slightly longer than a thickness n in a length direction.