JP2011220390A - Control device of hydraulic working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase energy regenerative efficiency while securing the anti-cavitation action, in a hydraulic working machine for regenerating energy of oil discharged from a hydraulic actuator as engine assist force via a regenerative motor.SOLUTION: In a turning circuit of a hydraulic excavator, the accumulator 32 is arranged as a hydraulic pressure source for anti-cavitation, and in turning deceleration, while rotating the regenerative motor 26 by regenerative oil taken out of the meter-out side of a turning motor 12, the oil of the accumulator 32 is supplied as anti-cavitation oil to the meter-in side via a control valve 25.

Description

  The present invention relates to a control device that performs an energy regenerative action when turning and decelerating in a hydraulic working machine such as a hydraulic excavator.

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

  As shown in FIG. 4, the hydraulic excavator is configured such that an upper swing body 2 is mounted on a crawler type lower traveling body 1 so as to be rotatable around a vertical axis X, and an excavation attachment 3 is mounted on the upper swing body 2. The

  The excavation attachment 3 includes an up and down boom 4, an arm 5 attached to the tip of the boom 4, a bucket 6 attached to the tip of the arm 5, and a boom, an arm, and a bucket cylinder for operating them ( (Hydraulic cylinder) 7,8,9.

  Further, the lower traveling body 1 and the upper swing body 2 are driven and turned by a travel motor and a swing motor (hydraulic motor) (not shown), respectively.

  In this hydraulic excavator, energy due to the inertia of the upper-part turning body 2 works during turning deceleration.

  Further, since the boom cylinder 7 is always subjected to a load in the boom lowering direction due to the weight of the attachment, etc., pressure is always applied to the extending side (boom raising side) of the cylinder 7, and the oil discharged therefrom is Have a certain energy.

  As means for effectively using the energy of such a hydraulic actuator, as disclosed in Patent Document 1, a regenerative motor is connected to the engine, and the regenerative motor is rotated by oil discharged from the hydraulic actuator. Techniques for assisting are known.

  This known technique will be described with reference to FIG. 5, taking a turning circuit as an example.

  In the figure, 10 is a hydraulic pump as a hydraulic source driven by the engine 11, and 12 is a turning hydraulic motor (hereinafter referred to as a turning motor) that is rotated by pressure oil from the hydraulic pump 10 to drive the upper swing body 2. Therefore, a control valve 13 is provided between the hydraulic pump 10 and the tank T and the swing motor 12 and is a hydraulic pilot type switching valve that is switched and operated by a pilot pressure from a remote control valve (not shown). 13 controls the supply / discharge of pressure oil to / from the swing motor 12 (rotation / stop, rotation direction, rotation speed of the swing motor 12).

  That is, when the remote control valve is not operated, the control valve 13 is set to the neutral position A shown in the figure. When the remote control valve is operated, the control valve 13 is moved from the neutral position A to the left side (for example, the left turn position) Same as the right turn position).

  At the neutral position A of the control valve 13, motor both-side conduits 14, 15 connecting the control valve 13 and the turning motor 12 (the left turning conduit on the left side and the right turning conduit on the right side) 14, 15 are connected to the pump 10. Since it is blocked, the turning motor 12 does not rotate.

  From this state, when the remote control valve is operated to the left turning side and the control valve 13 is switched to the left turning position B, the pressure oil is supplied from the pump 10 to the left turning pipeline 14 and the turning motor 12 rotates to the left. The upper swing body 2 turns left.

  On the other hand, when the remote control valve is operated to the right turning side and the control valve 13 is switched to the right turning position C, the pump oil is supplied to the right turning pipeline 15 and the turning motor 12 rotates to the right. The upper swing body 2 turns right.

  On the other hand, relief valves 16 and 17 as brake valves are provided opposite to each other between the two turning pipes 14 and 15, and in parallel therewith, a check valve for anti-cavitation (for preventing cavitation = oil suction) 18 and 19 are provided in an opposing arrangement.

  The outlet side of both relief valves 16 and 17 and the inlet side of both check valves 18 and 19 are connected by a communication passage 20, and this communication passage 20 is connected to the tank T.

  In the configuration so far, for example, when the control valve 13 returns from the left turning position B to the neutral position A, the turning motor 12 and the both turning pipelines 14 and 15 are disconnected from the pump 10 and the tank T, and the pressure applied to the turning motor 12 is increased. The supply of oil and the return of oil from the turning motor 12 to the tank T are stopped.

  Here, since the swing motor 12 tries to continue the left turn due to the inertia of the upper swing body 2, a pressure is generated in the right turn pipeline (meter-out side pipeline) 15 on the outflow side, and this reaches a certain value. Then, the relief valve 17 on the right side of the figure opens and the oil in the right turning pipe line 15 passes through the relief valve 17 -the communication path 20 -the check valve 18 on the left side of the figure and enters the left turning pipe line (meter-in side pipe line) 14. Enters and flows into the turning motor 12.

  At this time, if the left turning pipe line 14 tends to have a negative pressure, tank oil is sucked up from the communication path 20 to the left turning pipe line 14 via the check valve 18 to prevent cavitation. That is, the anti-cavitation action is automatically performed.

  Thereby, since the turning motor 12 receives a braking force while inertially rotating, it stops gently. The same applies when stopping from a right turn.

  The double line arrows in FIG. 5 indicate the flow of oil when turning left, and the black arrow indicates the flow of anti-cavitation oil (abbreviated as “anti-cavity oil” in the figure).

  On the other hand, a variable capacity type regenerative motor (hydraulic motor) 21 is connected to the engine 11, and the inlet side of the regenerative motor 21 is branched and connected to the motor side pipe lines 14 and 15 via a regenerative switching valve 22. The outlet side is connected to the tank T at both the side and right turn side regeneration lines 23 and 24, respectively.

  The regenerative switching valve 22 is switched and controlled between neutral, left-turning side regeneration, and right-turning side regeneration positions a, b, and c by a command from a controller (not shown). When decelerating to the right, the vehicle switches to the right-turning regeneration position c.

  Thereby, for example, when the left turn is decelerated, the oil discharged from the turn motor 12 is converted into the left turn side regeneration position of the meter-out side pipe line (right turn pipe line) 15, the left turn side regeneration line 23, and the regeneration switching valve 22. It is introduced into the regenerative motor 21 via b and the motor 21 rotates.

  That is, by driving the regenerative motor 21 with the oil discharged from the turning motor 12, the energy of the oil is converted into rotational energy and regenerated (in this case, regenerated as engine assist force).

JP 2003-120616 A

  As described above, the energy efficiency of the system can be improved by regenerating the energy of the return oil from the turning motor 12 as rotational energy.

  However, in the above-described known technology, on the other hand, a part of the return oil is used as the oil for anti-cavitation on the meter-in side. Therefore, the flow rate (regeneration flow rate) that can be used for regeneration is reduced by this anti-cavitation flow rate. .

  Further, since the high pressure oil on the meter-out side is decompressed by the relief valve 14 and returned to the meter-in side, energy loss due to this decompression occurs.

  Due to these two points, there is a problem that the ratio of the actual regenerative energy to the regenerative energy is small, that is, the regenerative efficiency is poor.

  Therefore, the present invention provides a control device for a hydraulic working machine that can increase energy regeneration efficiency while ensuring an anti-cavitation action.

  According to the first aspect of the present invention, the oil discharged from the hydraulic pump driven by the engine is supplied to the hydraulic actuator via the control valve, and the regenerative motor is driven by the oil discharged from the hydraulic actuator. A hydraulic working machine control device configured to convert energy into rotational energy and regenerate includes an accumulator as a hydraulic source for anti-cavitation, and the oil in the accumulator is supplied to the hydraulic actuator via the control valve. The meter-in side pipe is configured to be supplied for anti-cavitation.

  According to a second aspect of the present invention, in the configuration of the first aspect, the regenerative motor is configured as a pump motor that performs a motor action and a pump action, and the regenerative motor is pumped while the regenerative action is not performed. The anti-cavitation oil is supplied to the accumulator.

  According to a third aspect of the present invention, in the configuration of the first aspect, a back pressure valve having a variable set pressure is provided in a tank line for returning the oil discharged from the hydraulic actuator to the tank, and an accumulator is provided in the tank line upstream of the back pressure valve. In addition to branching the inflow line, connect this accumulator inflow line to the accumulator that is the hydraulic source for anti-cavitation, and when the pressure of this accumulator is below the set value, The oil in the tank line is supplied to the accumulator, and when the pressure of the accumulator is equal to or higher than a set value, the pressure set value of the back pressure valve is relatively lowered to reduce the pressure to the accumulator. The oil supply is stopped.

  According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, a pump assist accumulator is provided separately from the accumulator serving as an anti-cavitation hydraulic power source, and the pump assist accumulator includes: It is configured to accumulate excess oil exceeding the regenerative capacity of the regenerative motor and supply the accumulated oil to the pump discharge pipe.

  According to the present invention, the return oil from the hydraulic actuator is not used as anti-cavitation oil as in the known technique, but the separately provided accumulator oil is sent to the meter-in side to perform the anti-cavitation action. Thus, the flow rate (regenerative flow rate) that can be supplied to the regenerative motor can be increased.

  Further, there is no energy loss when the meter-out side oil is decompressed by the relief valve and returned to the meter-in side as in the known art.

  With these two points, the energy regeneration efficiency can be greatly increased while ensuring the anti-cavitation action.

  In this case, according to the second aspect of the present invention, the regenerative motor configured as a pump motor performs the pumping action, and according to the third aspect of the present invention, the set pressure of the back pressure valve is increased, thereby causing the anti-cavitation in each accumulator. Oil can be supplied and accumulated.

  According to the invention of claim 4, a pump assist accumulator for accumulating surplus oil on the meter-out side exceeding the regenerative capacity of the regenerative motor is provided separately from the accumulator serving as a hydraulic source for anti-cavitation. Since the oil accumulated in the accumulator is supplied to the discharge side of the hydraulic pump to perform the pump assist action, energy can be used effectively.

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. 1 is a schematic side view of a hydraulic excavator to which the present invention is applied. It is a circuit block diagram which shows a prior art.

  An embodiment of the present invention will be described with reference to FIGS.

  The embodiment is taken as an example when applied to a swing circuit of a hydraulic excavator.

In the following embodiment,
(A) Between the hydraulic pump 11 as a hydraulic source driven by the engine 11 and the tank T and the turning motor 12, neutral, left-turning, and right-turning positions a, b by pilot pressure from a remote controller (not shown) , A control valve 25 is provided which is a hydraulic pilot type switching valve that is switched between c and c. The control valve 25 supplies and discharges pressure oil to and from the swing motor 12 (rotation / stop of the swing motor 12, rotation direction, rotation). Speed) is controlled,
(B) Relief valves 16 and 17 as brake valves are provided opposite to each other between the two turning pipes 14 and 15, and in parallel therewith, a check valve for anti-cavitation (for preventing cavitation = oil suction) 18 and 19 are provided in an opposing arrangement, and the outlet side of both relief valves 16 and 17 and the inlet side of both check valves 18 and 19 are connected by a communication passage 20, and this communication passage 20 is connected to the tank T. Point,
(C) When the control valve 25 returns from the left turning position B to the neutral position A, for example, the turning motor 12 and both turning pipelines 14 and 15 are disconnected from the pump 10 and the tank T, and pressure oil is supplied to the turning motor 12. And the point where the return of the oil in the tank T from the turning motor 12 stops,
(D) In this case, since the swing motor 12 tries to continue the left turn due to the inertia of the upper swing body 2, pressure is generated in the right turn pipeline (meter-out side pipeline) 15 on the outflow side, and this is constant. When the value is reached, the relief valve 17 on the right side of the figure opens and the oil in the right turning pipe line 15 passes through the relief valve 17 -the communication path 20 -the check valve 18 on the left side of the figure and the left turning pipe line (meter-in side pipe line). ) Entering 14 and flowing into the turning motor 12,
(E) At this time, when the left turning pipeline 14 tends to have a negative pressure, tank oil is sucked from the communication passage 20 to the left turning pipeline 14 via the check valve 18 to prevent cavitation,
(F) A variable displacement type regenerative motor (hydraulic motor) 26 is connected to the engine 11, and the inlet side of the regenerative motor 26 is branched and connected to the motor side pipe lines 14 and 15 via the regenerative switching valve 22. A point where the outlet side is connected to the tank T on both the regenerative line 23 and 24 on the revolving side and the right turn side,
(G) The regenerative switching valve 22 is switched and controlled by the controller 27 between neutral, left-turning side regeneration, right-turning side regeneration positions a, b, and c. By switching to the right turn side regenerative position c at the time of right turn deceleration, oil discharged from the turn motor 12, for example, at the time of left turn deceleration, the meter-out side line (right turn line) 15, left turn The regenerative motor 26 is driven by oil that is introduced into the regenerative motor 26 via the side regenerative line 23 and the regenerative switching valve 22 via the left revolving side regenerative position b, that is, the oil that is discharged from the revolving motor 12. Thus, the configuration is such that oil energy is converted into rotational energy and regenerated (in this case, regenerated as engine assist force), which is the same as the known technique shown in FIG.

First embodiment (corresponding to claims 1 and 2 of the claims, see FIG. 1)
The control valve 25 includes anti-cavitation passages 25a and 25a communicating with both the swirling conduits 14 and 15 at the neutral position A, and an accumulator discharge conduit 28 is connected to the anti-cavitation passages 25a and 25a.

  On the other hand, an accumulator inflow line 30 is connected to the inlet line 29 of the regenerative motor 26, and the accumulator discharge line 28 and the accumulator inflow line 30 are connected via an accumulator switching valve 31 as an accumulator as a hydraulic source for anti-cavitation. 32 to be selectively connected.

  A tank line 33 is branched and connected to the accumulator inflow line 30, and the tank line 33 is connected to the tank T via the accumulator switching valve 31.

  The accumulator switching valve 31 includes a discharge position (i) where the accumulator (32) communicates with the accumulator discharge line (28), a storage position (b) where the inlet line (29) of the regenerative motor (26) communicates with the accumulator (32), and the inlet line (29) as the accumulator (32). An accumulator / tank position C that communicates the tank pipe 33 with the tank T and is controlled to be switched between positions a to c by the controller 27.

  The regenerative motor 26 is configured as a pump motor that performs a pump action and a motor action, and is switched between a pump action state and a motor action state by the operation of the regulator 34 based on a command from the controller 27.

  In addition, an operation sensor 35 that detects an operation of a remote control valve (not shown) and a pressure sensor 36 that detects a pressure accumulated in the accumulator 32 are provided as sensors, and signals from these are input to the controller 27.

  Based on these sensor signals, the controller 27 controls the regenerative switching valve 22 and the accumulator switching valve 31 so that an anti-cavitation action and a regenerative action are performed during turning deceleration.

  The operation of the control device including the operation of the controller 27 will be described.

  Taking the case where the control valve 25 returns from the left turning position B to the neutral position A as an example, the turning motor 12 is decelerated by the braking action of the relief valve 17.

  At this time, the regenerative switching valve 22 is switched to the left turning side regenerative position b by a command from the controller 27 that has received the operation signal, and the oil discharged from the turning motor 12 is turned to the left turning side regenerative line 23, the regenerative switching valve 22, The regenerative motor 26 is introduced into the regenerative motor 26 through the path of the regenerative motor inlet pipe 29.

  Thereby, the regenerative motor 26 rotates, the energy of the return oil is converted into rotational energy, and is regenerated as an engine assist force.

  On the other hand, the accumulator switching valve 31 is set to the discharge position (i), and the pressure oil accumulated in the accumulator (32) passes through the switching valve (31), the accumulator discharge line (28) and the neutral position (a) of the control valve (25). Cavitation is prevented by being supplied to.

  Thus, instead of using the return oil from the turning motor 12 as anti-cavitation oil, the oil of the accumulator 32 provided separately is sent to the meter-in side (left turning side in the above example) to perform the anti-cavitation action. The flow rate (regenerative flow rate) that can be supplied to the regenerative motor 26 can be increased as compared with the known technology.

  Further, there is no energy loss when the pressure on the meter-out side (right turning side in the above example) is reduced by the relief valve and returned to the meter-in side as in the known art.

  With these two points, the energy regeneration efficiency can be greatly increased while ensuring the anti-cavitation action.

  In this embodiment, when the pressure of the accumulator 32 detected by the pressure sensor 36 falls below a set value (pressure necessary for performing the anti-cavitation action), the regeneration motor 26 performs the regeneration action. While it is not performed (when turning is stopped or when turning, which can be determined by an operation signal), a pump action command is issued from the controller 27 to the regulator 34, and based on this, the regenerative motor 26 performs a pump action.

  At this time, the accumulator switching valve 31 is switched to the accumulation position B, and the pressure oil discharged from the regenerative motor 26 by the pump action is supplied to the accumulator 32 via the accumulator inflow conduit 30 and the accumulator switching valve 31 and accumulated. .

  When the accumulator pressure becomes close to the set value, the accumulator switching valve 31 is switched to the accumulation / tank position C. When the accumulator switching valve 31 recovers to the set value or more, it returns to the discharge position a and simultaneously the pump rotation of the regenerative motor 26 stops.

  In this way, the accumulator 32 can be supplemented with anti-cavitation oil.

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

  In the second embodiment, the means for supplying oil to the accumulator 32 is different from that of the first embodiment.

  That is, a back pressure valve (a check valve with a spring) 38 whose set pressure is controlled to be relatively high and low by the controller 27 is provided in the tank line 37 for returning the oil discharged from the swing motor 12 to the tank T. An accumulator inflow conduit 30 is branched and connected to a tank line 37 upstream of the back pressure valve 38.

  In this configuration, when the accumulator pressure is equal to or higher than the set value, that is, when a sufficient amount of oil is accumulated in the accumulator 32 to perform the anti-cavitation action, the controller 27 that receives the pressure signal from the pressure sensor 36 , The back pressure valve 38 is set to a low pressure, allowing the oil to return to the tank T.

  On the other hand, when the accumulator pressure falls below the set value, the back pressure valve 38 is set to a high pressure based on a command from the controller 27, and the accumulator switching valve 31 is switched to the accumulation position b. As a result, the return oil is supplied and accumulated in the accumulator 32.

  When the accumulator pressure is restored to the set value or more by this accumulation action, the back pressure valve 38 is set to a low pressure again, the accumulator switching valve 31 is set to the discharge position A, and the supply of oil to the accumulator 32 is stopped.

  In the second embodiment, the regenerative motor 26 performs only the motor action.

3rd Embodiment (refer FIG. 3)
In the third embodiment, on the premise of the configuration of the first embodiment, a relatively low-pressure accumulator that is a hydraulic source for anti-cavitation (same as the accumulator 32 of the first embodiment, hereinafter referred to as the first accumulator). In addition to 32, a relatively high pressure pump assist accumulator (hereinafter referred to as a second accumulator) 39 is provided.

  A pump connection line 41 is branchedly connected to the discharge line 40 of the hydraulic pump 10, and the pump connection line 41 is connected to an accumulator switching valve (hereinafter referred to as a first accumulator switching valve) 31 for the first accumulator 32. It is connected to the second accumulator 39 via an accumulator switching valve (hereinafter referred to as a second accumulator switching valve) 42 having the same configuration.

  Similarly to the first accumulator 32, the second accumulator 39 has an accumulator inflow conduit 43 (corresponding to the inflow conduit 30 in FIG. 1), a tank conduit (corresponding to the tank conduit 33) 44, and A pressure sensor 45 for detecting the accumulator pressure is provided.

  In this configuration, when surplus oil exceeding the regenerative capacity of the regenerative motor 26 is generated at the time of turning deceleration (for example, it can be detected by providing a flow sensor in the regenerative lines 23 and 24), and the second accumulator 39 is provided. When the accumulated pressure is equal to or lower than the set value, the controller 27 sets the second accumulator switching valve 42 to the accumulation position B.

  As a result, surplus oil is introduced and accumulated in the second accumulator 39 through the paths of the regenerative switching valve 22, the inlet pipe 29, the accumulator inflow pipe 43, and the second accumulator switching valve. After the accumulation, the second accumulator switching valve 42 is switched to the accumulation / tank position C or the discharge position A by a signal from the controller 27 based on the pressure signal from the pressure sensor 45.

  Then, the second accumulator switching valve 42 is switched to the discharge position a at an appropriate time during the operation of the pump (especially when a large flow rate is required. For example, it can be determined by an operation signal from the operation sensor 35).

  Thereby, the accumulated pressure oil can be merged into the pump discharge line 40. That is, surplus energy can be effectively used for pump assist, and the load on the hydraulic pump 10 can be reduced.

  The configuration of the third embodiment can also be applied when the circuit configuration of the second embodiment is taken.

DESCRIPTION OF SYMBOLS 10 Hydraulic pump 11 Engine 12 Turning motor 14 Left turning pipeline 15 Right turning pipeline 21 Regenerative motor 22 Regeneration switching valve 23,24 Regeneration line 25 Control valve 25a Anti-cavitation passage 26 Regeneration motor 27 Controller 28 Accumulator discharge pipeline 29 Regeneration Motor inlet line 30 Accumulator inflow line 31 Accumulator switching valve 32 Accumulator 33 Tank line 35 Operation sensor 36 Pressure sensor 37 Tank line 38 Back pressure valve 39 Pump assist accumulator 40 Pump discharge line 41 Pump connection line 42 Accumulator Switching valve 43 Accumulator inflow line

Claims (4)

  The oil discharged from the hydraulic pump driven by the engine is supplied to the hydraulic actuator via the control valve, and the regenerative motor is driven by the oil discharged from the hydraulic actuator to convert the oil energy into rotational energy. The hydraulic working machine control device is configured to regenerate and include an accumulator as a hydraulic source for anti-cavitation, and the oil of the accumulator is anti-cavitated to the meter-in side pipe of the hydraulic actuator via the control valve. A control device for a hydraulic working machine, characterized in that it is configured to be supplied for use.   The regenerative motor is configured as a pump motor that performs a motor action and a pump action, and while the regenerative action is not performed, the regenerative motor performs a pump action to supply oil for anti-cavitation to the accumulator. 2. The control device for a hydraulic working machine according to claim 1, wherein the control device is configured as described above.   A back pressure valve with variable set pressure is provided in the tank line that returns the oil discharged from the hydraulic actuator to the tank, and the accumulator inflow conduit is branched and connected to the tank line upstream of the back pressure valve. Is connected to an accumulator serving as a hydraulic source for anti-cavitation, and when the pressure of the accumulator is equal to or lower than a set value, the pressure set value of the back pressure valve is relatively increased, thereby Supplying to the accumulator, and when the pressure of the accumulator is equal to or higher than a set value, the supply of oil to the accumulator is stopped by relatively reducing the pressure set value of the back pressure valve. The control device for a hydraulic working machine according to claim 1.   In addition to the accumulator serving as the anti-cavitation hydraulic source, a pump assist accumulator is provided.The pump assist accumulator accumulates excess oil exceeding the regeneration capacity of the regenerative motor, and stores the accumulated oil. The control device for a hydraulic working machine according to any one of claims 1 to 3, wherein the control device is configured to be supplied to the pump discharge pipe.

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