JP2012002261A - Hydraulic device for driving rotating body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic device for driving a rotating body capable of eliminating a bleed-off flow rate accompanied by an energy loss while maintaining a favorable operating feeling the same as the characteristic of a bleed-off circuit.SOLUTION: The rotational speed of a motor 3 is controlled not only based on the amount of the operation of an operation part 7 but also on first deviation between target pressure according to the operation amount of the operation part 7 and the discharge pressure of a pump 2, and second deviation between the first deviation and the rotational speed of the pump 2.

Description

  The present invention relates to a hydraulic device for driving a revolving structure, for example, a hydraulic device such as a hydraulic apparatus for driving a revolving structure of a construction machine such as a hydraulic excavator.

  Conventionally, as a hydraulic device for driving a revolving structure, there are an open center system having a bleed-off circuit and a closed center system having no bleed-off circuit.

  In the open center system having the bleed-off circuit, as shown in FIG. 3, a pump 102 that discharges the liquid that rotates the swivel body 101, a motor 103 that drives the pump 102, and the liquid discharged from the pump 102 And a switching valve 115 for switching the flow path. The pump 102 is connected to the tank 117 via a bleed-off circuit BOC (indicated by a bold line in the figure).

  The switching valve 115 is, for example, an electromagnetic valve, and is switched according to an operation amount (operation angle) of a lever that operates the swing body 101. The switching valve 115 has a first position S1 for flowing the liquid of the pump 102 to the hydraulic motor 116 of the swivel body 101 so as to turn the swivel body 101 in one direction, and the pump 102 so as to turn the swivel body 101 in the other direction. Switching is made between a second position S2 for flowing the liquid to the hydraulic motor 116 of the swivel body 101 and a neutral position S0 between the first position S1 and the second position S2. This neutral position S0 has a bleed-off passage D, and when the switching valve 115 is switched to the neutral position S0, the liquid of the pump 102 flows into the tank 117 via the bleed-off circuit BOC.

  By using the bleed-off circuit BOC, the turning speed of the turning body 101 can be adjusted according to the load (for example, the loaded weight) applied to the turning body 101. Specifically, when the load on the swing body 101 is large, even if the operation amount is the same, that is, the switching position of the switching valve 115 is the same, the swing speed of the swing body 101 can be reduced, and the load on the swing body 101 is reduced. Is small, the turning speed of the turning body 101 can be increased. As a result, a good operational feeling can be obtained.

  However, in the open center system having the bleed-off circuit, a flow rate that does not contribute to work out of the fluid discharged from the pump 102 flows to the tank 117 via the bleed-off circuit BOC. For this reason, there is a problem that a loss flow is always generated, energy loss occurs, and the oil temperature rises.

  Specifically, when the lever is not operated, the switching valve 115 is in the neutral position S0, and the entire flow rate supplied from the pump 102 flows out to the tank 117 via the bleed-off passage D and the bleed-off circuit BOC. It was.

  Further, when the lever is operated, the opening degree of the bleed-off passage D is changed so as to be narrowed down at the time of transition to switch the switching valve 115 from the neutral position S0 to the first position S1 or the second position S2, and at the same time, the pump The opening between the port P and the load port A or B is gradually increased, and oil is supplied to the hydraulic motor 116 while generating a bleed-off flow by the bleed-off passage D and the bleed-off circuit BOC. A good operation feeling is obtained according to the size. However, since a bleed-off flow occurs even at such a switching position according to the operation amount, energy loss occurs and the problem of an increase in oil temperature occurs.

  On the other hand, in the closed center system without the bleed-off circuit, the supply flow rate is changed so that the differential pressure between the load pressure of the rotating body and the pump pressure is constant (Japanese Patent Laid-Open No. 4-136509: Patent Document 1). reference).

  However, in the closed center system without the bleed-off circuit, the supply flow rate is uniquely determined by the amount of lever operation regardless of the load, so that the same good operational feeling as the characteristics of the bleed-off circuit can be obtained. There wasn't.

JP-A-4-136509

  Accordingly, an object of the present invention is to provide a hydraulic device for driving a revolving structure capable of eliminating the bleed-off flow rate accompanied by energy loss while maintaining the same good operational feeling as the characteristics of the bleed-off circuit.

In order to solve the above problem, a hydraulic device for driving a revolving structure according to the present invention includes:
A pump that discharges liquid that swirls the swivel body; and
A variable speed motor for driving the pump;
A pressure sensor for detecting the discharge pressure of the pump;
A rotational speed detector for detecting the rotational speed of the pump;
A control unit for controlling the rotation speed of the motor;
A target pressure setting unit for setting a target pressure according to the operation amount of the operation unit;
A first addition point for obtaining a first deviation between the target pressure set by the target pressure setting unit and the current pump discharge pressure detected by the pressure sensor;
A second summing point for obtaining a second deviation between the first deviation output from the first summing point and the current rotational speed of the pump detected by the rotational speed detector;
The control unit controls the rotational speed of the motor based on the second deviation output from the second addition point.

  Here, in this specification, the “operation unit” is for operating the revolving body manually or the like, for example, a lever, a handle, a pedal, or the like. The “operation amount” refers to an amount by which the operation unit is moved manually or the like, for example, an operation angle of a lever or a rotation angle of a handle. The “pump discharge pressure” means a pressure directly related to the pump discharge pressure, such as a discharge line pressure and a load line pressure.

  According to the hydraulic device for driving the revolving structure of the present invention, the target pressure is set by the target pressure setting unit according to the operation amount of the operation unit, and is set by the target pressure setting unit by the first addition point. A first deviation between the target pressure and the current discharge pressure of the pump detected by the pressure sensor is obtained, and the first deviation output from the first addition point and the rotation speed detector are detected by the second addition point. The second deviation from the current pump rotational speed is obtained, and the rotational speed of the motor is controlled based on the second deviation output from the second addition point by the control section. Rotation of the motor based on the first deviation between the target pressure corresponding to the operation amount of the operation unit and the discharge pressure of the pump and the second deviation between the first deviation and the rotation speed of the pump. Control the speed Therefore, without using a bleed-off circuit, it is possible to obtain the same operational feeling as the characteristics of the bleed-off circuit, and since the liquid is not bleed-off, there is little energy loss and the liquid temperature rise is prevented. it can.

  Therefore, the bleed-off flow rate with energy loss can be eliminated while maintaining the same good operational feeling as the characteristics of the bleed-off circuit.

Further, in the hydraulic device for driving the revolving structure of one embodiment,
A maximum speed setting unit for setting the maximum rotation speed of the pump corresponding to the maximum speed of the revolving structure;
A target speed limiter configured to limit the first deviation output from the first addition point so as not to exceed a maximum rotation speed of the pump set by the maximum speed setting unit;

  According to the hydraulic device for driving the revolving structure of this embodiment, the target speed limiting unit is configured such that the first deviation output from the first addition point is set by the maximum speed setting unit. Therefore, the revolving structure can be safely turned without turning the revolving structure at a speed exceeding the maximum speed of the revolving structure.

  According to the hydraulic device for driving the revolving structure of the present invention, not only the magnitude of the operation amount of the operation unit, but also the first deviation between the target pressure corresponding to the operation amount of the operation unit and the discharge pressure of the pump, Since the motor speed is controlled based on 1 deviation and the second deviation of the pump speed, the bleed-off flow with energy loss is eliminated while maintaining the same good operating feeling as the characteristics of the bleed-off circuit. be able to.

It is a simplified block diagram which is one Embodiment of the hydraulic apparatus for driving a turning body of the present invention. It is a simplified block diagram which shows the control algorithm of a hydraulic apparatus. It is a simplified block diagram which shows the conventional hydraulic apparatus.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 shows a simplified configuration diagram as an embodiment of a hydraulic device for driving a revolving structure of the present invention. FIG. 2 shows a simplified configuration diagram showing a control algorithm of the hydraulic device of the present invention. This hydraulic device is, for example, a hydraulic device that drives a turning body of a construction machine such as a hydraulic excavator. The swivel body is, for example, a cab of a hydraulic excavator.

  As shown in FIGS. 1 and 2, a pump 2 that discharges the liquid that rotates the swivel body 1, a variable-speed motor 3 that drives the pump 2, and a switch that switches the flow path of the liquid discharged from the pump 2. And a valve 15.

  The switching valve 15 is, for example, an electromagnetic valve, and is switched according to the operation amount of the operation unit 7 that operates the swing body 1. The operation unit 7 is for operating the revolving body 1 manually or the like, and is, for example, a lever, a handle, a pedal, or the like. The operation amount of the operation unit 7 refers to the amount by which the operation unit 7 is moved manually or the like, for example, the lever operation angle or the handle rotation angle.

  The switching valve 15 has a first position S1 for flowing the liquid of the pump 2 so as to turn the swivel body 1 in one direction, and a second position S2 for flowing the liquid of the pump 2 so as to turn the swivel body 1 in the other direction. And the neutral position S0 where the liquid flow of the pump 2 is blocked.

  In the first position S 1 of the switching valve 15, the liquid discharged from the pump 2 flows into the first port of the hydraulic motor 16 that drives the revolving body 1, flows out of the second port of the hydraulic motor 16, and the tank 17 is discharged. In the second position S <b> 2 of the switching valve 15, the liquid discharged from the pump 2 flows into the second port of the hydraulic motor 16 that drives the swing body 1, flows out of the first port of the hydraulic motor 16, and the tank 17 is discharged.

  A brake valve 18 is provided in the flow path between the switching valve 15 and the hydraulic motor 16. The brake valve 18 includes a counter balance valve 20 and a check valve 21. A relief valve 14 and a check valve 19 are sequentially provided in the flow path between the pump 2 and the switching valve 15.

  The hydraulic device includes a pressure sensor 4, a rotation speed detector 5, a control unit 6, a target pressure setting unit 8, a first addition point 11, and a second addition point 12.

  The pressure sensor 4 is connected to a flow path between the pump 2 and the check valve 19 and detects the discharge pressure of the pump 2. In addition, the discharge pressure of the pump 2 is the discharge pressure of the pump 2 such as the pressure of the discharge line 31 between the pump 2 and the switching valve 15 and the pressure of the load line 32 between the switching valve 15 and the swing body 1. You may detect with the pressure directly related.

  The rotational speed detector 5 detects the rotational speed of the pump 2. The target pressure setting unit 8 sets a target pressure according to the operation amount of the operation unit 7. The target pressure setting unit 8 sets the target pressure based on, for example, a table determined in advance with respect to the relationship between the operation amount of the operation unit 7 and the target pressure.

  The first addition point 11 obtains a first deviation between the target pressure set by the target pressure setting unit 8 and the current discharge pressure of the pump 2 detected by the pressure sensor 4. The second summing point 12 obtains a second deviation between the first deviation output from the first summing point 11 and the current rotational speed of the pump 2 detected by the rotational speed detector 5.

  The control unit 6 controls the rotational speed of the motor 3 based on the second deviation output from the second addition point 12. The control unit 6 includes a speed control unit 6a and a current control unit 6b. The speed control unit 6a performs PID control, for example. The current control unit 6b performs inverter control, for example.

  The hydraulic device has a maximum speed setting unit 9 and a target speed limiter 10. The maximum speed setting unit 9 sets the maximum rotation speed of the pump 2 corresponding to the maximum speed of the swing body 1. The target speed limiter 10 is connected between the first addition point 11 and the second addition point 12, and the first deviation output from the first addition point 11 is set by the maximum speed setting unit 9. The maximum rotation speed of the pump 2 is limited so as not to exceed.

  A target speed generator 13 is connected between the first addition point 11 and the target speed limiter 10. The target speed generation unit 13 generates a target speed of the rotational speed of the pump 2 based on the first deviation output from the first addition point 11. For example, the target speed generation unit 13 generates a target speed based on a table determined in advance with respect to the relationship between the first deviation output from the first addition point 11 and the target speed.

  Next, the operation of the hydraulic device will be described.

  First, when the operation unit 7 is operated in a direction in which the swing body 1 is swung in one direction, the switching valve 15 is switched to the first position S1, and the liquid discharged from the pump 2 is supplied to the hydraulic motor. 16 flows into the first port 16 and flows out from the second port of the hydraulic motor 16 to rotate the swing body 1 in one direction. At this time, since the control unit 6 controls the rotational speed of the motor 3 based on the second deviation output from the second addition point 12, the control unit 6 loads the load (for example, load weight) applied to the revolving structure 1. ), The turning speed of the swing body 1 can be adjusted. That is, the control unit 6 can reduce the turning speed of the revolving structure 1 when the load of the revolving structure 1 is large, and can increase the turning speed of the revolving structure 1 when the load of the revolving structure 1 is small.

  On the other hand, when the operation unit 7 is operated in a direction in which the swing body 1 is swung in the other direction, the switching valve 15 is switched to the second position S2, and the liquid discharged from the pump 2 is supplied to the hydraulic motor. 16 flows into the second port 16 and flows out from the first port of the hydraulic motor 16 to rotate the swing body 1 in the other direction. At this time, since the control unit 6 controls the rotational speed of the motor 3 based on the second deviation output from the second addition point 12, the control unit 6 loads the load (for example, load weight) applied to the revolving structure 1. ), The turning speed of the swing body 1 can be adjusted. That is, the control unit 6 can reduce the turning speed of the revolving structure 1 when the load of the revolving structure 1 is large, and can increase the turning speed of the revolving structure 1 when the load of the revolving structure 1 is small.

  When the operation unit 7 is not operated, the switching valve 15 is switched to the neutral position S0, and the liquid discharged from the pump 2 does not flow into the hydraulic motor 16.

  According to the hydraulic device for driving the revolving structure having the above configuration, the target pressure is set according to the operation amount of the operation unit 7 by the target pressure setting unit 8, and the target pressure setting unit 8 is set by the first addition point 11. Is obtained from the first summing point 11 by the second summing point 12. The first deviation between the target pressure set by the pressure sensor 4 and the current discharge pressure of the pump 2 detected by the pressure sensor 4 is obtained. And a second deviation between the current rotational speed of the pump 2 detected by the rotational speed detector 5 and the rotation of the motor 3 based on the second deviation output from the second addition point 12 by the control unit 6. Since the speed is controlled, that is, not only the magnitude of the operation amount of the operation unit 7, but also the first deviation between the target pressure corresponding to the operation amount of the operation unit 7 and the discharge pressure of the pump 2, the first deviation and the pump Second deviation with a rotational speed of 2 Since the rotational speed of the motor 3 is controlled based on the above, the same good operating feeling as the characteristics of the bleed-off circuit can be obtained without using the bleed-off circuit, and the liquid does not bleed off. The loss of the liquid is small and the temperature rise of the liquid can be prevented.

  Therefore, the bleed-off flow rate with energy loss can be eliminated while maintaining the same good operational feeling as the characteristics of the bleed-off circuit.

  Further, the target speed limiter 10 limits the first deviation output from the first addition point 11 so that it does not exceed the maximum rotational speed of the pump 2 set by the maximum speed setting unit 9. The revolving body 1 can be safely turned without turning the body 1 at a speed exceeding the maximum speed of the revolving body 1.

  In addition, this invention is not limited to the above-mentioned embodiment. For example, the maximum speed setting unit 9 and the target speed limiting unit 10 may be omitted. The configuration of the control unit 6 may be a configuration other than the speed control unit 6a and the current control unit 6b.

  The setting of the target pressure by the target pressure setting unit 8 and the generation of the target speed by the target speed generation unit 13 may be obtained by a predetermined characteristic curve in addition to the predetermined table.

DESCRIPTION OF SYMBOLS 1 Revolving body 2 Pump 3 Variable speed motor 4 Pressure sensor 5 Rotational speed detector 6 Control part 6a Speed control part 6b Current control part 7 Operation part 8 Target pressure setting part 9 Maximum speed setting part 10 Target speed limit part 11 1st Additional point 12 Second additional point 13 Target speed generation unit 14 Relief valve 15 Switching valve 16 Hydraulic motor 17 Tank 18 Brake valve 19 Check valve 20 Counter balance valve 21 Check valve 31 Discharge line 32 Load line BOC Bleed-off circuit

Claims (2)

A pump (2) for discharging a liquid for rotating the rotating body (1);
A variable speed motor (3) for driving the pump (2);
A pressure sensor (4) for detecting the discharge pressure of the pump (2);
A rotational speed detector (5) for detecting the rotational speed of the pump (2);
A control unit (6) for controlling the rotational speed of the motor (3);
A target pressure setting unit (8) for setting a target pressure according to an operation amount of the operation unit (7);
A first addition point (11) for obtaining a first deviation between the target pressure set by the target pressure setting unit (8) and the discharge pressure of the current pump (2) detected by the pressure sensor (4); ,
A second addition for obtaining a second deviation between the first deviation output from the first addition point (11) and the current rotational speed of the pump (2) detected by the rotational speed detector (5). With a point (12),
The controller (6) controls the rotational speed of the motor (3) based on the second deviation output from the second addition point (12). Hydraulic device. The hydraulic device for driving a revolving structure according to claim 1,
A maximum speed setting unit (9) for setting the maximum rotation speed of the pump (2) corresponding to the maximum speed of the revolving structure (1);
Target speed limit for limiting the first deviation output from the first addition point (11) so as not to exceed the maximum rotational speed of the pump (2) set by the maximum speed setting section (9). A hydraulic device for driving a revolving structure, characterized in that it has a section (10).

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