JP2010101096A - Hydraulic control device for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control device for a working machine allowing an operator to change a set value for difference in pressure of a flow rate control valve freely, based on the system for ensuring the fixed flow rate of actuator with the flow rate control valve with pressure compensation function. <P>SOLUTION: A circuit configuration constituted by connecting a plurality of hydraulic actuators used as an oil pressure source in common with a hydraulic pump in parallel and operating and controlling with the control valves, respectively, includes the flow rate control valve 30 with the pressure compensation function for controlling the flow rate to keep difference in pressure between before and after a pressure oil supply opening in a control valve 29 for crushing to a set value. The flow rate control valve 30 is constituted to allow the set value for the difference in pressure to be changed through pilot pressure when operating the control valve 29 for crushing. On the other hand, a pilot pressure control valve 41 for changing control pressure by orders from the controller 40 based on the operation of a means 39 for ordering set value for difference in pressure is provided to allow the operator to freely change the set value for the difference in pressure of the flow rate control valve 30 with the pilot pressure control valve 41. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hydraulic control device for a working machine such as a hydraulic excavator and a crusher configured by diverting the hydraulic excavator.

  The background art will be described using a hydraulic excavator as an example.

  As shown in FIG. 4, the excavator has an upper swing body 2 mounted on a crawler-type lower traveling body 1 so as to be rotatable about a vertical axis. The upper swing body 2 has a boom 3, an arm 4, a bucket 5, And a work attachment A composed of boom, arm, and bucket cylinders (hydraulic cylinders) 6 to 8 as hydraulic actuators for operating them, and excavation and loading work are performed.

  Further, as other hydraulic actuators, left and right traveling motors that drive the lower traveling body 1 and a swing motor (none of which is shown) that swings the upper swing body 2 are provided.

  On the other hand, this hydraulic excavator may be diverted to other work machines, for example, a crusher as shown in FIG.

  In this case, a crushing device 9 as an option for crushing a concrete structure or the like by opening and closing by a crushing cylinder (optional actuator) (not shown) is attached to the tip of the work attachment A instead of the bucket 5. Accordingly, there are seven hydraulic actuators including a crushing cylinder.

  This hydraulic actuator group and a control valve group which is a hydraulic pilot switching valve for individually controlling these hydraulic actuator groups are usually divided into two groups and driven by separate pumps.

  A specific example is shown in FIG.

  The first group G1 on the left side of the figure includes an arm cylinder 7, a swing motor 10, a left traveling motor 11L, a crushing cylinder 12, and control valves 13 to 16 that are hydraulic pilot switching valves that individually control these, in order from the upper side of the figure. And is connected in parallel to the first pressure oil supply line L1.

  The second group G2 on the right side of the figure consists of a boom cylinder 6, a bucket cylinder 8, a right travel motor 11R, and control valves 17 to 19 which are hydraulic pilot switching valves for individually controlling these, in order from the upper side of the figure. The pressure oil supply line L2 is connected in parallel.

  In addition, remote control valves 20 to 26 are provided for each control valve, and the control valves 13 to 19 are stroke-operated by the pilot pressure from the remote control valves 20 to 26 to control the operation of each actuator.

  On the other hand, first and second pumps 27 and 28 are provided as pressure oil supply sources for the hydraulic actuator group, and the discharge oil of the first hydraulic pump 27 is supplied to the first group G1 via the first pressure oil supply line L1. The oil discharged from the second hydraulic pump 28 is supplied to the second group G2 via the second pressure oil supply line L2. T is a tank.

  In this circuit configuration, there is a problem that the actuator flow rate on the high load pressure side is insufficient when the load pressure (operating pressure) of the simultaneously operating hydraulic actuators is different at the time of composite operation in which a plurality of hydraulic actuators in the same group are simultaneously operated. is there.

  For example, when the swing motor 10 and the arm cylinder 7 are operated simultaneously, the circuit flow rate of the swing motor 10 having a high load pressure is insufficient, and the swing speed becomes slow. Further, when the crushing cylinder 12 and other actuators are operated simultaneously, the circuit flow rate of the crushing cylinder on the high load pressure side is insufficient.

  As a means for solving this problem, for example, a technique described in Patent Document 1 is known.

  In this technology, the required circuit flow rate of a specific hydraulic actuator is secured by restricting the circuit flow rate of a hydraulic actuator other than the hydraulic actuator with the highest load pressure (hereinafter referred to as a specific hydraulic actuator) with a throttle valve. It has been taken.

  However, according to this technique, the pressure loss due to the throttle is large and the energy efficiency (fuel consumption) is deteriorated. In addition, the throttle valve is provided for all hydraulic actuators other than the specific hydraulic actuator, so that the valve configuration is complicated and the cost is increased. .

  On the other hand, a technology is also known in which a flow control valve with pressure compensation is provided upstream of a control valve for a specific hydraulic actuator, and the flow control is performed by this flow control valve so as to keep the differential pressure across the pressure oil supply opening constant. (For example, see Patent Document 2).

According to this technology, the circuit flow rate determined by the set value of the differential pressure across the front and rear can be secured regardless of the load pressure. Therefore, the required circuit flow rate for the specific hydraulic actuator can be reduced during combined operation of the specific hydraulic actuator and other actuators. Can be supplied. In addition, the pressure loss is small and energy efficiency is good as compared with the known technique of Patent Document 1, and the valve configuration is simple.
JP 2003-301803 A JP 2006-183413 A

  However, according to the known pressure compensation flow control technology, the flow rate can be controlled by the differential pressure setting value regardless of the load pressure as described above, but the differential pressure setting value is constant and cannot be changed. The corresponding flow rate characteristics could not be obtained, and the operability sometimes deteriorated in this respect.

  Accordingly, the present invention presupposes a flow rate control method with pressure compensation, and the differential pressure set value, that is, the flow rate characteristic can be freely changed according to the operator's preference, thereby improving the operability of the hydraulic control of the work machine. A device is provided.

  According to a first aspect of the present invention, there is provided a hydraulic control device for a work machine in which a plurality of hydraulic actuators are connected in parallel to a hydraulic pump serving as a common hydraulic source, and each of which is controlled by a control valve. Pressure that controls the flow rate so that the differential pressure across the pressure oil supply opening of the specific control valve is kept at a set value on a pipe that connects a specific control valve that controls the operation of the specific hydraulic actuator among the hydraulic actuators A flow control valve with compensation is provided, and when the specific control valve is operated, the flow control valve is switched to a priority position where the discharge oil from the hydraulic pump is preferentially supplied to the specific control valve. The set value of the differential pressure varies depending on the pilot pressure applied to the pilot port. And a pilot pressure control valve for controlling the pilot pressure supplied to the flow control valve, a differential pressure set value command means operated by an operator, and an operation of the differential pressure set value command means The pilot pressure control valve is provided with control means for instructing a set value of the differential pressure.

  According to a second aspect of the present invention, in the configuration of the first aspect, a control valve for controlling the operation of any one of a traveling motor of a hydraulic excavator as a work machine, a turning motor, and a crushing cylinder as an optional actuator is provided. A flow control valve with pressure compensation, a pilot pressure control valve, and control means are provided as the specific control valve.

  According to a third aspect of the present invention, in the configuration of the first or second aspect, each of the flow rate control valves with pressure compensation is provided in a pipe line connecting a plurality of hydraulic pumps and the specific control valve. The oil whose flow rate is controlled by the valve is joined and supplied to the specific hydraulic actuator.

  According to a fourth aspect of the present invention, in the configuration of the third aspect, the hydraulic pump does not include a first hydraulic pump that drives a first group including a plurality of hydraulic actuators including the specific hydraulic actuator, and a specific hydraulic actuator. A second hydraulic pump that drives a second group of a plurality of hydraulic actuators is provided, and the first hydraulic pump and the specific control valve are connected to the first hydraulic pump as a flow control valve with pressure compensation. A second flow rate control valve is provided in each of the pipes connecting the flow rate control valve and the second hydraulic pump and the specific control valve, and the second flow rate control valve is configured to operate when the specific control valve is operated. 2 It is configured to switch to a priority position that preferentially supplies the oil discharged from the hydraulic pump to the specific control valve. The is intended.

  According to the present invention, in a circuit configuration in which a plurality of hydraulic actuators connected in parallel are driven by a common hydraulic pump, a flow rate control valve with pressure compensation is provided in a pipeline connecting the hydraulic pump and a specific control valve. Since the flow rate control is performed by the flow rate control valve so that the differential pressure across the pressure oil supply opening in the specific control valve is maintained at the set value, the basic hydraulic effect is as follows. Any one of the traveling motor, the turning motor, and the crushing cylinder) can be supplied with a flow rate determined by the set value regardless of the load pressure.

  Therefore, by providing a flow control valve with a hydraulic actuator having a high load pressure (for example, a crushing cylinder) as the specific hydraulic actuator, the specific hydraulic actuator and another hydraulic actuator having a lower load pressure can be operated simultaneously. The required circuit flow rate of the specific hydraulic actuator can be ensured during operation.

  Moreover, in such a flow rate control method with pressure compensation, the flow rate control valve is configured as a hydraulic pilot valve whose set value changes depending on the pilot pressure, and the pilot pressure of the flow rate control valve is set to a differential pressure setting operated by an operator. Since the control is performed according to the command from the value command means, the differential pressure set value of the flow control valve can be freely changed.

  That is, on the premise of the flow rate control method with pressure compensation, the flow rate characteristic of the specific hydraulic actuator can be freely changed according to the preference of the operator, thereby improving the operability.

  By the way, a work machine such as a hydraulic excavator is generally provided with a plurality (usually two as in claim 4) of hydraulic pumps, and the discharge amount of each pump is the hydraulic actuator (in claim 4, the first, To the second group).

  In this case, according to the third and fourth aspects of the present invention, a flow rate control valve with pressure compensation is provided in each pipe line connecting each hydraulic pump and the specific control valve, and oil whose flow rate is controlled by each flow rate control valve is supplied. Since they are combined and supplied to the specific hydraulic actuator, the range of flow rate control can be expanded. For this reason, operativity can be improved more.

  In the following embodiments, a hydraulic excavator diverted to a crusher is taken as an application object in accordance with the description of the background art.

1st Embodiment (refer FIG. 1)
In the first embodiment, the following points are the same as those of the prior art shown in FIG.

  (A) As a hydraulic actuator, in addition to the boom, arm, and bucket cylinders 6 to 8, left and right traveling motors 11L and 11R, a turning motor 10, and a crushing cylinder 12 for a crushing device are provided.

  (B) The hydraulic actuator group and the hydraulic pilot type control valve group for individually controlling the hydraulic actuator group are divided into first and second groups G1 and G2.

  (C) The first group G1 on the left side of the figure includes an arm cylinder 7, a turning motor 10, a left traveling motor 11L, a crushing cylinder 12, and a control valve 13 that is a hydraulic pilot switching valve for individually controlling them. , 14, 15, 29, and connected in parallel to the first pressure oil supply line L1.

  (D) The second group G2 on the right side of the figure includes a boom cylinder 6, a bucket cylinder 8, a right travel motor 11R, and control valves 17, 18, and 19 that are hydraulic pilot switching valves that individually control them. And is connected in parallel to the second pressure oil supply line L2.

  (E) A remote control valve 20 to 26 is provided for each control valve, and each control valve is stroke-operated by the pilot pressure from the remote control valves 20 to 26 to control the operation of each actuator.

  (F) First and second pumps 27 and 28 are provided as pressure oil supply sources for the hydraulic actuator group, and discharged oil from the first hydraulic pump 27 is transferred to the first group G1 via the first pressure oil supply line L1. The oil discharged from the second hydraulic pump 28 is supplied to the second group G2 via the second pressure oil supply line L2.

  The crushing control valve 29 has a different reference from the crushing control valve 16 shown in FIG.

  In the first embodiment, the crushing cylinder 12 having the highest load pressure in the first group G1 is used as a specific hydraulic actuator, and the crushing control valve 29 is used as a specific control valve, and the control valve 29 and the first hydraulic pump 27 are connected to each other. A flow rate control valve 30 with pressure compensation is provided at the most upstream portion of the one-pressure oil supply line L1.

  The flow control valve 30 is configured as a hydraulic pilot valve having a priority pilot port 31 on one side (left side in the figure) and a non-priority pilot port 32 on the opposite side (same right side). Is switched between the priority position A on the left side of the figure and the non-priority position B on the right side, and the flow rate is controlled. Reference numeral 33 denotes a spring of the flow control valve 30.

  The control valve 30 includes a passage (referred to as a right passage according to the direction of the drawing) 34 leading to the first pressure oil supply line L1 and a passage (referred to as a left passage) connected to the pressure oil supply opening of the crushing control valve 29. 35, the left passage 35 is a priority passage for preferentially sending pump discharge oil to the crushing control valve 29, and the right passage 34 is configured to supply the excess flow rate to the first pressure oil supply line L1 (the other control valves 13 to 15). ) Is a passage to send to.

  The priority side pilot port 31 of the flow control valve 30 has a load pressure (operating pressure) Poh when the crushing cylinder is operated, and the right pilot port 32 is supplied with a supply pressure Poi when the crushing cylinder is operated. Is added as pilot pressure.

  The left pilot line 36 communicates with the tank T through a throttle 38.

  Further, a pilot pressure control valve (electromagnetic proportional valve) 41 controlled by a differential pressure set value command means 39 and a controller 40 as a control means is connected to the non-priority pilot port 32, and the output of the pilot pressure control valve 41 Pe is also applied to the non-priority pilot port 32 as a pilot pressure.

  The differential pressure set value command means 39 is a so-called operation panel in which the operator selects the differential pressure set value stepwise in the form of, for example, “high speed”, “medium speed”, and “low speed” or continuously from low speed to high speed. When the command from the differential pressure set value command means 39 is applied to the pilot pressure control valve 41 via the controller 40, the differential pressure set value of the flow control valve 30 changes.

  The operation of this apparatus including this point will be described in detail.

  When the crushing control valve 29 is operated to the crushing cylinder extension side or the contraction side, the load pressure Poh of the crushing cylinder 12 is applied as a pilot pressure to the priority side pilot port 31 of the flow control valve 30 as described above. Thus, the control valve 30 is set to the priority position a.

  In this state, the discharge oil of the first hydraulic pump 27 is preferentially supplied to the crushing cylinder 12 via the left passage 35 of the flow control valve 30 and the crushing control valve 29, and surplus oil is supplied to the first pressure oil supply line. L1 is supplied.

  On the other hand, the pressure Poi supplied to the crushing cylinder 12 and the output (control pressure) Pe of the pilot pressure control valve 41 are applied to the right pilot port 32 as pilot pressure.

  As a result, the flow control valve 30 is balanced by the following pressure. In the following equation, A1 is the pressure receiving area of the flow control valve 30 with respect to the pilot pressures Poh and Poi, A2 is the pressure receiving area with respect to the pilot pressure Pe, and Fs is the spring force of the spring 33.

Poh · A1 + Fs = Poi · A1 + Pe · A2 …… Formula 1
Thereby, the front-rear differential pressure ΔP = Poi−Poh at the supply side opening of the crushing control valve 29 is expressed by the following equation.

ΔP = Poi−Poh = Fs / A1−Pe · A2 / A1 Equation 2
The flow rate Qo of the crushing control valve 29 is given by the following equation, where the opening area of the control valve 29 is Ao. Here, Cv is a flow coefficient, g is a gravitational acceleration, and γ is a specific gravity of hydraulic oil.

Qo = CvAo√ (2 g · ΔP / γ) …… Equation 3
As described above, the differential pressure set value is changed by controlling the control pressure Pe of the pilot pressure control valve 41 in the range of 0 to Fs / A2 through the operation of the differential pressure set value command means 39, and the flow rate of the crushing cylinder 12 is reduced to 0. It can be arbitrarily set within the range of ~ CvAo√ (2 g · Fs / A1γ).

  That is, when the operator operates the differential pressure set value command means 39 to the high speed side or the low speed side, a command of the pilot pressure Pe corresponding to the above operation is issued from the controller 40 to the pilot pressure control valve 41, and this pilot pressure Pe. The flow control according to is performed.

  For example, when the operator gives an instruction to increase the speed, the pilot pressure Pe decreases, the differential pressure ΔP increases from Expression 2, and the speed of the crushing cylinder 12 increases by increasing Qo from Expression 3. On the contrary, when a command to reduce the speed is issued, the pilot pressure Pe increases, the differential pressure ΔP decreases, and the operating speed of the crushing cylinder 12 decreases as Qo decreases.

  Note that when the crushing cylinder 12 is not operated, the pressure in the left pilot pipe line 36 decreases, so the flow control valve 30 is set to the non-priority position b. In this state, the discharge oil of the first hydraulic pump 27 is preferentially supplied to the first pressure oil supply line L1 (actuator other than the crushing cylinder 12).

  As described above, when the crushing cylinder 12 that is the specific hydraulic actuator is operated, the priority flow rate controlled by the flow rate control valve 30 with pressure compensation is supplied to the crushing cylinder 12. A constant flow rate is preferentially supplied regardless of the load pressure of the crushing cylinder 12 at the time of a composite operation in which other hydraulic actuators in the group G1 (the arm cylinder 7, the turning motor 10, and the left traveling motor 11L) are simultaneously operated. For this reason, the problem that the circuit flow rate of the crushing cylinder 12 having a high load pressure is insufficient and the operating speed is reduced can be solved.

  Moreover, in such a flow rate control system with pressure compensation, the flow rate control valve 30 is configured as a hydraulic pilot valve whose differential pressure set value changes depending on the pilot pressure, and the pilot pressure Pe of the flow rate control valve 30 is operated by an operator. Therefore, the differential pressure setting value of the flow control valve 30 can be freely changed.

  That is, on the premise of the flow rate control method with pressure compensation, the flow rate characteristic of the specific hydraulic actuator (crushing cylinder 12) can be freely changed according to the preference of the operator, thereby improving the operability.

Second embodiment (see FIG. 2)
In the following second and third embodiments, only differences from the first embodiment will be described.

  In the second embodiment, instead of the crushing cylinder 12, the swing motor 10 is a specific hydraulic actuator, the swing control valve 42 is a specific control valve, and the flow rate controlled by the flow control valve 30 is passed through the swing control valve 42. A configuration in which the rotation motor 10 is preferentially supplied is employed.

  According to this configuration, since a constant flow rate is supplied to the swing motor 10 regardless of the load pressure during the combined operation in which the swing operation in the first group G1 and other actuator operations are performed simultaneously, the circuit of the swing motor 10 The problem that the flow rate is insufficient and the operating speed decreases can be solved, and the turning speed can be freely changed according to the preference of the operator.

  In this case, since the crushing control valve 16 may have the same valve configuration as the crushing control valve 16 in the conventional circuit shown in FIG.

  By the way, the traveling motor 11L can be used as a specific hydraulic actuator to supply a priority flow rate thereto.

3rd Embodiment (refer FIG. 3)
In the third embodiment, for example, on the premise of the configuration of the first embodiment, the pressure compensation flow control with the same configuration as the pressure compensated flow control valve 30 of the first embodiment is also provided on the discharge side of the second hydraulic pump 28. A valve 30 '(hereinafter referred to as a first flow control valve and a second flow control valve) is provided.

  The second flow rate control valve 30 'is provided in a state where the left passage 35 communicates with the pressure oil supply opening of the crushing control valve 29 and the right passage 34 communicates with the second pressure oil supply line L2. 30, the load pressure Poh of the crushing cylinder 12 is applied to the priority side pilot port 31, and the supply pressure Poi when the crushing cylinder is operated and the control pressure Pe of the pilot pressure control valve 41 ′ are applied to the non-priority side pilot port 32. It is done.

  According to this configuration, the priority flow rate from the second hydraulic pump 28 controlled by the second flow rate control valve 30 ′ merges with the priority flow rate from the first hydraulic pump 27 supplied by the first flow rate control valve 30 route. And supplied to the crushing cylinder 12.

  Therefore, according to the second embodiment, for example, when the operator operates the differential pressure setting value command means 39 so as to increase the crushing cylinder flow rate, the first flow rate is from 0 to CvAo√ (2 g · Fs / A1γ). The flow rate can be controlled by the flow rate control valve 30 and the flow rate can be controlled by the second flow rate control valve 30 ′ in a range exceeding this (maximum 2 CvAo√ (2 g · Fs / A1γ)).

  That is, the flow rate of the crushing cylinder 12 can be continuously controlled in the range of 0 to 2 CvAo√ (2 g · Fs / A1γ), and the operating speed of the crushing cylinder 12 can be adjusted in a very wide range. Therefore, the operability can be further improved.

  The configuration of the third embodiment can be similarly applied when another actuator is a specific hydraulic actuator.

It is a circuit block diagram which shows 1st Embodiment of this invention. It is a circuit block diagram which shows 2nd Embodiment of this invention. It is a circuit block diagram which shows 3rd Embodiment of this invention. It is a schematic side view of a hydraulic excavator. It is a schematic side view of the state which diverted the hydraulic excavator to the crusher. It is a conventional circuit block diagram.

Explanation of symbols

G1 1st group G2 2nd group L1, L2 Pressure oil supply line 1 Lower traveling body of hydraulic excavator 2 Same, upper turning body A Same, work attachment 3 Boom constituting work attachment 4 Same, arm 5 Same, bucket 6 Boom Cylinder 7 Arm cylinder 8 Bucket cylinder 9 Crushing device 10 Rotating motor 11L Left traveling motor 11R Right traveling motor 12 Crushing cylinder as specific hydraulic actuator 13 Arm control valve 14 Turning control valve 15 Left traveling control valve 17 Boom control valve 18 control valve for bucket 29 control valve for crushing as specific control valve 27 first hydraulic pump 28 second hydraulic pump 29 control valve for crushing 30 flow rate with pressure compensation Valve 31 the flow control valves on each side pilot port 34 the controller 41 the pilot pressure control valve 42 swing control valve as right passageway 35 left passage 36,37 a pilot conduit 39 differential pressure set value command means 40 control means

Claims (4)

  In a hydraulic control device for a work machine in which a plurality of hydraulic actuators are connected in parallel to a hydraulic pump serving as a common hydraulic source and are each controlled by a control valve, the hydraulic pump and a specific hydraulic pressure among the plurality of hydraulic actuators A flow control valve with pressure compensation that controls the flow rate so that the differential pressure across the pressure oil supply opening of the specific control valve is maintained at a set value on a pipe line connecting a specific control valve that controls the operation of the actuator. The flow rate control valve is switched to a priority position where the discharge oil from the hydraulic pump is preferentially supplied to the specific control valve when the specific control valve is operated, and is added to the pilot port. Configured so that the set value of the differential pressure varies with pressure, and A pilot pressure control valve that controls the pilot pressure supplied to the flow rate control valve, a differential pressure set value command means that is operated by an operator, and the pilot pressure control valve that is operated based on the operation of the differential pressure set value command means. A hydraulic control device for a work machine, comprising: a control unit that commands a set value of the differential pressure.   A flow control valve with pressure compensation as a specific control valve, which is a control valve for controlling the operation of one of a traveling motor of a hydraulic excavator as a work machine, a swing motor, and a crushing cylinder as an optional actuator, 2. The hydraulic control device for a work machine according to claim 1, further comprising a pilot pressure control valve and a control means.   A flow rate control valve with pressure compensation is provided in each pipe line connecting a plurality of hydraulic pumps and the specific control valve, and the oil whose flow rate is controlled by each flow rate control valve is joined to the specific hydraulic actuator. The hydraulic control device for a work machine according to claim 1, wherein the hydraulic control device is configured to be supplied.   As the hydraulic pump, a first hydraulic pump that drives a first group that includes a plurality of hydraulic actuators including the specific hydraulic actuator, and a second that drives a second group that includes a plurality of hydraulic actuators that do not include the specific hydraulic actuator. A hydraulic pump, and as a flow control valve with pressure compensation, a first flow control valve, a second hydraulic pump and the specific control are connected to a pipe connecting the first hydraulic pump and the specific control valve. A second flow rate control valve is provided in each pipe line connecting the valve, and the second flow rate control valve supplies the discharge oil from the second hydraulic pump to the specific control valve when the specific control valve is operated. 4. The work machine according to claim 3, wherein the work machine is configured to switch to a priority position to be preferentially supplied. Hydraulic control apparatus.

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