JPH0454012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic control circuit, and more particularly to a hydraulic control circuit for a self-propelled hydraulic machine equipped with a plurality of actuators.

[Prior Art] Hydraulic working machines, such as hydraulic excavators, have a plurality of switching valves arranged to form a hydraulic control circuit, and perform various tasks such as traveling, turning, and vertical movement under the action of the switching valves. ing.

For example, in the embodiment according to the prior art shown in FIG. 1, the left travel hydraulic motor, the swing hydraulic motor, the arm drive cylinder, the boom drive cylinder, the bucket drive cylinder, and the right travel hydraulic motor are It is configured to be driven by a hydraulic pump and a second hydraulic pump 8.

That is, the left travel hydraulic motor 2, the swing hydraulic motor 4, and the arm drive cylinder 6 are driven by the first pump 8, while the boom drive cylinder 10, bucket drive cylinder 12, and right travel hydraulic motor are driven by the first pump 8. 14 is a second hydraulic pump 16
It is configured to be driven by.

In this way, the first pump 8, the second pump 1
6 to perform the 6 types of work, these first
A first cylinder is connected between the pump 8 and the left travel hydraulic motor 2, the swing hydraulic motor 4, and the arm drive cylinder 6.
A complex control valve group 18 is installed, and a second hydraulic pump 16, a right travel hydraulic motor 14, a bucket drive cylinder 12, and a boom drive cylinder 10 are installed.
A second composite control valve group 20 is interposed between the two. In this case, the first composite control valve group 18 is a first switching valve 22 connected to the left travel hydraulic motor 2.
and a second switching valve 2 connected to the swing hydraulic motor 4
4 and a third switching valve 26 connected to the arm driving cylinder 6, and the first switching valve 22, the second switching valve 24, and the third switching valve 26 are each connected in parallel to the first pump 8. That's what happens.

On the other hand, the second composite control valve group 20 includes a fourth switching valve 28 connected to the right travel hydraulic motor 14 and a fifth switching valve 30 connected to the bucket drive cylinder 12.
and a sixth switching valve 32 connected to the boom driving cylinder 10, and the fourth switching valve 28, fifth switching valve 30, and sixth switching valve 32 are connected in parallel to the second hydraulic pump 16. It is configured like this. In addition, in the figure, reference numeral 33 is a tank that stores oil to be recirculated.

Therefore, in the above configuration, when the first switching valve 22 and the fourth switching valve 28 are switched and operated, the left traveling hydraulic motor 2 and the right traveling hydraulic motor 14 are connected to the pump 8 and the pump 16, respectively. Pressure oil is supplied, and the hydraulic excavator (not shown) moves forward or backward under the rotational action of these hydraulic motors 2 and 14.

[Problem to be Solved] However, in such a self-propelled state, for example, when the second switching valve 24 is switched to drive the swing hydraulic motor 4, the main pipe 34 connected to the first pump 8 is disconnected. Pressure oil is diverted from the center bypass conduit 35 that extends through the center bypass conduit 35 to a conduit 36 that further branches, and as a result, pressure oil reduced by the amount of the diverted amount flows to the left travel hydraulic motor 2. . That is, although sufficient pressure oil is flowing into the right-hand hydraulic motor 14, a reduced amount of pressure oil flows into the left-hand hydraulic motor 2 by the amount flowing into the pipe 36, so that the entire hydraulic excavator is damaged. As a result, it will curve to the left.

Similarly, if the bucket drive cylinder 12 is driven when the left travel hydraulic motor 2 and the right travel hydraulic motor 14 are self-propelled in a balanced state, the cylinder extending from the second pump 16 A center bypass conduit 39 extending through a main conduit 38
Pressure oil flows into a conduit 40 that further branches from there, and therefore the pressure oil for the right travel hydraulic motor 14 is reduced by that amount. Therefore, the hydraulic excavator as a whole ends up turning to the right.

In this state where the hydraulic motor 2 and the hydraulic motor 14 are trying to move straight while maintaining their respective balances, the hydraulic excavator can turn to the left or right by operating the other various driving switching valves. Therefore, if it is desired to maintain straight running, it becomes impossible to use any of the swing hydraulic motor, arm drive cylinder, boom drive cylinder, and bucket drive cylinder. That is, while the vehicle is moving straight, it is difficult to perform other tasks at the same time.

The present invention has been made in order to solve the above-mentioned problems, and is an object of the present invention, in which a switching valve for driving a cylinder or the like is operated in a self-propelled hydraulic machine to perform work other than driving while the machine is running. Even if I did,
An object of the present invention is to provide a hydraulic control circuit for a self-propelled hydraulic machine that can maintain its self-propelled state.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a self-propelled hydraulic machine comprising: a hydraulic pump; a tank connected to the hydraulic pump; and a first traveling hydraulic motor. a first control valve group that includes a first switching valve that drives an actuator, one or more switching valves that are connected in tandem to the first switching valve to drive an actuator, and a first center bypass line; a second control valve that includes a second switching valve that drives a travel hydraulic motor; one or more switching valves that are connected in tandem to the second switching valve to drive an actuator; and a second center bypass pipe. a first control valve, which is provided between the hydraulic pump, the first control valve group, and the second control valve group, and which diverts pressure oil to the switching valves constituting each of the control valve groups through a main pipe.
a flow divider valve including a valve body and a second valve body, when the first and second hydraulic motors for travel are driven,
The first valve body of the diverting valve is switched in response to an energizing signal from the actuator of at least one of the first control valve group or the second control valve group, and in the switching position, the hydraulic pump is switched to the first control valve. The first switching valve of the group is connected to another switching valve that energizes the actuator, and the second valve body of the branch valve switches in response to the energizing signal of the actuator, and in the switching position, the hydraulic pump is switched to the second switching valve. A second switching valve of the control valve group is connected to another switching valve that energizes the actuator, while a first valve body and a second valve body of the diverter valve are connected to the first and second switching valves in the non-switching position. Pressure oil is introduced directly into the center bypass line.

[Function] When the hydraulic excavator (not shown) is about to move forward, the first switching valve and the second switching valve are switched, and the pressure oil supplied from the hydraulic pump is transferred to the first traveling hydraulic motor via the diversion valve. and is sent to the second travel hydraulic motor. While the hydraulic excavator is traveling as described above, for example, when driving the swing hydraulic motor as an actuator, a signal is supplied to the first valve body and the second valve body that constitute the diverting valve, and the diverting valve is activated. is switched, and pressure oil is supplied from the first valve body and the second valve body to the swing hydraulic motor via the main pipe and the switching valve. This causes the hydraulic excavator to perform a turning operation, but does not prevent the hydraulic excavator from moving straight ahead or the like.

[Embodiments] Next, preferred embodiments of the hydraulic control circuit according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, reference numeral 50 indicates a tank for storing oil, reference numeral 52 indicates a first hydraulic pump connected to the tank 50, and reference numeral 54 indicates a second hydraulic pump connected to the tank 50. A hydraulic pump is shown. The discharge sides of the first pump 52 and the second pump 54 are connected to a flow dividing valve 56 . Details of the flow dividing valve 56 will be described later.

Therefore, the first main line 58 connected to the branch valve 56 is connected to a center bypass line 59, and this center bypass line 59 is connected to a first switching valve 60, a second switching valve 60, and a second switching valve 60, which are connected in tandem from the upstream side. It is connected to the switching valve 62 and the third switching valve 64, and is ultimately connected to return to the tank 50. In this case, the first switching valve 60 to the third switching valve
The switching valve 64 is configured as a 4-port, 3-position valve.

Next, a relief valve 68 is provided in a pipe line 66 branching from the center bypass pipe line 59 and reaching the tank 50.
is inserted, and pressure oil at a predetermined pressure or higher supplied from the main pipe line 58 is led out from the pipe line 66 to the tank 50.

In the above configuration, the P port of the first switching valve 60 is connected to the center bypass line 59, and the R port is connected to the line 66.
On the other hand, the A port of the first switching valve 60 is connected to one port of the left travel hydraulic motor 70, and the B port is similarly connected to the other port of the left travel hydraulic motor 70.

The P port of the second switching valve 62 is connected to the center bypass pipe 59 via the check valve 72, and
The R port of the second switching valve 62 is connected to the pipe line 66. Further, the A port of the second switching valve 62 is connected to one port of a swing hydraulic motor 74 as an actuator, and the second switching valve 62 is connected to one port of a swing hydraulic motor 74 as an actuator.
The second B port is connected to the other port of the swing hydraulic motor 74. Note that this second switching valve 62
The P port is connected to the relief valve 7 via the supply line 76.
8, and the output side of this relief valve 78 is connected to the center bypass pipe 59. Furthermore, the P port of the third switching valve 64 is connected to the supply line 76, and the R port thereof is connected to the line 66. On the other hand, the A port of the third switching valve 64 is connected to an arm driving cylinder 80 as an actuator.
The B port is connected to the other port of the arm driving cylinder 80.

In this case, the second switching valve 62 and the third switching valve 64 have a check mechanism therein, as can be easily understood from the figure.

The first switching valve 60 configured as described above,
The second switching valve 62 and the third switching valve 64 constitute a first composite control valve group 82 . The supply pipe line 76 is connected to a pipe line 86 connected to one port of the flow dividing valve 56 via a check valve 84.

Next, a second main line 90 extending from the other port of the diverter valve 56 is connected to the tank 50 via a center bypass line 91. A relief valve 9 is provided in a pipe line 92 branching from the center bypass pipe line 91.
Moreover, this pipe line 92 is connected to the center bypass pipe line 91 and finally reaches the tank 50. A fourth switching valve 96, a fifth switching valve 98, and a sixth switching valve 100, which are 4-port, 3-position valves, are connected in tandem to the center bypass pipe 91.

Note that, similarly to the above, the fifth switching valve 98 and the sixth switching valve 100 include a check mechanism therein.

The P port of the fourth switching valve 96 is connected to the center bypass line 91, and the R port thereof is connected to the line 92. On the other hand, the A port of the fourth switching valve 96 is connected to one port of the right travel hydraulic motor 102, and the B port thereof is connected to the other port of the right travel hydraulic motor 102.

The R port of the fifth switching valve 98 is connected to the pipe line 92, and its P port is connected to the center bypass pipe line 91 via the check valve 104. The A port of this fifth switching valve 98 is connected to one port of the bucket drive cylinder 106 as an actuator, and the B port is connected to the other port of the bucket drive cylinder 106. Further, the R port of the sixth switching valve 100 is connected to the pipe line 92, while the P port is connected to the pipe line 107,
This conduit 107 is connected to the center bypass conduit 91 via a supply conduit 117 in which a relief valve 108 is interposed. The A port of the sixth switching valve 100 is connected to one port of the boom driving cylinder 110, and its B port is also connected to the other port of the boom driving cylinder 110 as an actuator.

Note that the supply pipe line 117 is connected to the check valve 114.
It is connected to conduit 86 via.

It will be easily understood that the switching valves and pipelines configured in this manner constitute the second control valve group 115.

Next, the flow dividing valve 56 will be explained. Diversion valve 5
Reference numeral 6 denotes a spring offset type valve, and the flow dividing valve 56 includes a first valve body 120 having orifices 116 and 118 having different diameters inside thereof, and orifices 122 and 124 having similarly different diameters. and a second valve body 126.

The hydraulic control circuit for the self-propelled hydraulic machine according to the present invention is basically configured as described above.
Next, its action and effects will be explained.

In the normal state, the left travel hydraulic motor 70,
Swing hydraulic motor 74, arm drive cylinder 8
0, right travel hydraulic motor 102, bucket drive cylinder 106, and boom drive cylinder 11
0 is not driven at all, the pressure oil supplied by the first hydraulic pump 52 and the second hydraulic pump 54 is divided by the diverter valve 56 and flows through the main pipes 58,
90 and the tank 5 via the center bypass lines 58, 90 and the center bypass lines 59, 91.
Flows into 0. In such a state, when the switching valve 60 and the switching valve 96 are energized to occupy the switching position, the left travel hydraulic motor 70 and the right travel hydraulic motor 102 rotate under the action of the switching valve 60 and the switching valve 96, and the hydraulic motor 102 (not shown) rotates. The shovel begins forward movement.
Therefore, while the vehicle is traveling forward in this way, for example, when attempting to drive the turning hydraulic motor 74, the switching valve 62 is operated to switch. That is, when a lever (not shown) located at the driver's seat of the hydraulic excavator is operated, a signal related to the switching operation by this lever is transmitted as a signal to the first valve body 120 and the second valve body 120 constituting the diverter valve 56.
It will be introduced into the valve body 126 of.

As a result, the first valve body 120 supplies the pressure oil of the first hydraulic pump 52 to the orifices 116 and 118 under the switching action of the switching valve 62, and
The pressure oil flowing through 6 reaches the main pipe 58 and is fed from the first switching valve 60 to the left travel hydraulic motor 70. On the other hand, a part of the pressure oil branched from the orifice 118 constituting the first valve body 120 flows toward the second switching valve 62 via the conduit 86 to drive the swing hydraulic motor 74.

On the other hand, the second valve body 126, which constitutes the flow dividing valve 56 together with the first valve body 120, is also switched. That is, the pressure oil flowing from the second pump 54 reaches the fourth switching valve 96 via the orifice 124 and rotates the right travel hydraulic motor 102, but at the same time, the orifice 122
The branched pressure oil passing through reaches the pipe line 86. That is, the pressure oil flowing through the orifice 118 and the orifice 122 join together through the pipe line 86. At that time, since the fifth switching valve 98 and the sixth switching valve 100 are in a neutral state, the combined pressure oil is transferred to the check valve 84 and the sixth switching valve 100.
114 and supply lines 76 and 117. The pressure oil passing through the supply pipe line 76 reaches the second switching valve 62, and as a result, sufficient pressure oil is supplied to the turning hydraulic motor 74, and the hydraulic excavator turns. At this time, the check valve 72 connected to the switching valve 62 acts to prevent blow-through, that is, to prevent pressure oil from escaping, and to supply sufficient driving force to the swing hydraulic motor 74. On the other hand, orifice 116 and orifice 124
Pressure oil is branched from the first switching valve 60 and the fourth switching valve 60, respectively.
It flows to the switching valve 96. Therefore, the orifice 1
16. If the diameters of the discharge ports of the orifices 124 are selected in the same manner, even if a predetermined pressure oil is diverted to the swing hydraulic motor 74, running can be maintained in a balanced state between the left and right sides. In addition, in that case,
If the pressure in the pipeline downstream of the check valves 84, 114 exceeds a predetermined pressure, the relief valves 78, 108
Of course, the excess pressure oil is supplied to the tank 50. Note that the third switching valve 64 is in the neutral position as shown in the figure.

As can be easily understood from the above, the first
The hydraulic pump 52 and the second hydraulic pump 54 are rotated at the same speed, so that the pressure oil is transferred from the respective discharge sides to the first valve body 120 and the second valve body 12 of the distribution valve 56.
6, pressure oil of the same pressure is fed to the first switching valve 60 and the fourth switching valve 96 via the orifices 116, 124 of the valve bodies 120, 126. As a result, the left travel hydraulic motor 70 and the right travel hydraulic motor 102 can receive pressure oil of the same pressure and rotate in the same direction and at the same number of rotations. During this time, when attempting to turn the hydraulic excavator to the left by energizing the left turning hydraulic motor 74,
The diversion valve 56 is switched, and the switching valve 62 is also switched. By this, in particular, the orifice 11
8, 122, the pressure oil passes through the main pipe 86, reaches the check valve 84 and the switching valve 62, and the left-turning hydraulic motor 74 is energized. Switching valve 64,9
Pressure oil will not be diverted to 8,100. This is because each is in a neutral position. Furthermore, the arm driving cylinder 8 is not limited to the swing hydraulic motor 74.
0. Even if the bucket drive cylinder 106 and the boom drive cylinder 110 are attempted to be driven during self-propelled operation in the same way as described above, the direction of movement of the bucket drive cylinder 106 and the boom drive cylinder 110, such as turning, will not be displaced. Note that the signal input to the diverter valve 56 is, for example, a limit switch disposed close to an operating lever disposed in the driver's seat of the hydraulic excavator, and a left/right travel signal from the limit switch and other signals. What is necessary is to extract the signal when the actuator signal is input in a superimposed manner and operate the flow dividing valve 56.

[Effects of the Invention] As is clear from the above description, when another work is to be performed during the traveling operation, the traveling is not hindered by the biasing of the actuator for performing that work. In other words, as shown in the example, when another work signal is input at the same time as left/right travel, the pressure oil is diverted by the diversion valve that branches the pressure oil from the pump, and the pressure oil is divided between travel and other work. Since these are performed in parallel, it is possible to perform a plurality of different functions in a self-propelled state. Moreover, it goes without saying that in states other than self-propelled operation, various tasks can be accomplished at the same operating rate as in the past.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a hydraulic control circuit for a hydraulic excavator according to the prior art, and FIG. 2 is an explanatory diagram of a hydraulic control circuit according to the present invention. 2... Hydraulic motor for left travel, 4... Hydraulic motor for swinging, 6... Cylinder for arm drive, 8... First hydraulic pump, 10... Cylinder for boom drive,
12... Cylinder for bucket drive, 14... Hydraulic motor for right travel, 16... Second hydraulic pump, 18
...first compound control valve group, 20...second compound control valve group, 22...first switching valve, 24...second switching valve,
26...Third switching valve, 28...Fourth switching valve, 30
...Fifth switching valve, 32...Sixth switching valve, 34...
Main pipe line, 36...Pipe line, 38...Main pipe line, 40...
...Pipeline, 50...Tank, 52...First hydraulic pump, 54...Second hydraulic pump, 56...Diversion valve,
58... Main pipeline, 59... Center bypass pipeline,
60...First switching valve, 62...Second switching valve, 64
...Third switching valve, 66...Pipe line, 68...Relief valve, 70...Hydraulic motor for left travel, 72...Check valve, 74...Hydraulic motor for turning, 76...
Supply pipe line, 78... Relief valve, 80... Arm drive cylinder, 82... First composite control valve group, 8
4...Check valve, 86...Pipe line, 90...Main pipe line, 91...Center bypass line, 92...Pipe line, 94...Relief valve, 96...Fourth switching valve,
98...Fifth switching valve, 100...Sixth switching valve, 1
02... Hydraulic motor for right travel, 104... Check valve, 106... Cylinder for bucket drive, 10
7...Pipe line, 108...Relief valve, 110...
Boom drive cylinder, 112...Pipe line, 114
...Check valve, 115...Second composite control valve group,
116... Orifice, 117... Supply pipe, 1
18... Orifice, 120... Valve body, 122,
124... Orifice, 126... Valve body.

Claims (1)

[Scope of Claims] 1. A self-propelled hydraulic machine, comprising: a hydraulic pump, a tank connected to the hydraulic pump, a first switching valve that drives a first traveling hydraulic motor, and the first switching valve. a first control valve group including one or more switching valves that are connected in tandem to drive an actuator and a first center bypass line; a second switching valve that drives a second travel hydraulic motor; a second control valve group including one or more switching valves connected in tandem to the second switching valve to drive an actuator and a second center bypass line; the hydraulic pump; the first control valve group; A first control valve which is provided between the two control valve groups and diverts pressure oil to the switching valves constituting the respective control valve groups through the main pipe.
a flow divider valve including a valve body and a second valve body, when the first and second hydraulic motors for travel are driven,
The first valve body of the diverting valve is switched in response to an energizing signal from the actuator of at least one of the first control valve group or the second control valve group, and in the switching position, the hydraulic pump is switched to the first control valve. The first switching valve of the group is connected to another switching valve that energizes the actuator, and the second valve body of the branch valve switches in response to the energizing signal of the actuator, and in the switching position, the hydraulic pump is switched to the second switching valve. A second switching valve of the control valve group is connected to another switching valve that energizes the actuator, while a first valve body and a second valve body of the diverter valve are connected to the first and second switching valves in the non-switching position. A hydraulic control circuit for a self-propelled hydraulic machine characterized by introducing pressure oil directly into a center bypass pipe. 2. A hydraulic control circuit for a self-propelled hydraulic machine according to claim 1, wherein the first valve body and the second valve body of the diverter valve each have a fixed orifice. 3 In the hydraulic control circuit according to claim 2, one fixed orifice of the first valve body and one fixed orifice of the second valve body constituting the flow dividing valve are connected to each other via a pipe line when switching. A hydraulic control circuit for a self-propelled hydraulic machine consisting of communication. 4. In the hydraulic control circuit according to claim 3, the pipeline is branched and connected to a supply pipeline, and the supply pipeline is connected to another switching valve in the first control valve group and to the other switching valve in the second control valve group. A hydraulic control circuit for a self-propelled hydraulic machine connected to other switching valves. 5. In the hydraulic control circuit according to claim 4, each supply pipe line is provided with a check valve, and the output side of each check valve is further provided with a check valve that closes the passage to the center bypass pipe line. A hydraulic control circuit for a self-propelled hydraulic machine connected to a valve. 6. In the hydraulic circuit according to claims 1 to 5, the self-propelled hydraulic machine is a hydraulic control circuit for a self-propelled hydraulic machine including a hydraulic shovel. 7. In the hydraulic control circuit according to claim 6, the other switching valves constituting the first control valve group include a switching valve that drives the swing hydraulic motor and a switching valve that drives the arm cylinder, On the other hand, the other switching valves constituting the second control valve group are a hydraulic control circuit for a self-propelled hydraulic machine that includes a switching valve that drives a boom cylinder and a switching valve that drives a bucket cylinder.