JP5672995B2 - Hydraulic control equipment for construction machinery - Google Patents

Description

  The present invention relates to a hydraulic control apparatus that controls an operation of a hydraulic actuator by operating a hydraulic pilot type hydraulic control valve by a remote control valve using a pilot pump as a pilot pressure source in a construction machine such as an excavator.

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

  In an excavator, pressure oil from a main pump driven by an engine as a prime mover is supplied to a hydraulic actuator via a hydraulic pilot type hydraulic control valve (control valve), while a remote control valve using a pilot pump as a hydraulic source is used. A configuration is adopted in which the operation of the hydraulic actuator is controlled by operating the hydraulic control valve.

  Here, the pilot pump is generally driven by an engine together with the main pump.

  However, according to this engine drive system, the capacity of the pilot pump must be set large so that a pump output that does not hinder work can be obtained even when the engine is running at low speed.

  For this reason, there is a problem that the pilot pump becomes expensive and energy is unnecessarily consumed (high energy loss) by the pump when the engine rotates at high speed.

  Therefore, as shown in Patent Document 1, an electric motor driving method for driving a pilot pump with an electric motor has been proposed.

  This will be described with reference to FIG.

  A main pump 2 is connected to the engine 1, and discharged oil is supplied from the main pump 2 to a hydraulic actuator 4 via a hydraulic pilot type hydraulic control valve 3.

  Reference numeral 5 denotes a remote control valve (hydraulic pilot valve). A pilot pressure corresponding to the amount of operation of the lever 6 as an operation means is sent from the remote control valve 5 to the pilot port of the hydraulic control valve 3, thereby actuating the hydraulic control valve 3 Thus, the operation of the hydraulic actuator 4 is controlled.

  Note that a plurality of hydraulic control valves 3, hydraulic actuators 4 and remote control valves 5 are provided in the actual machine, but only one is shown here for simplification of the drawing. This is the same in FIGS. 1 and 2 showing the embodiment of the present invention.

  On the other hand, a pilot pump 8 is driven by an electric motor 7 that uses a battery (not shown) as a power source, and a pilot primary pressure is supplied from the pilot pump 8 to the remote control valve 6. T is a tank.

  The pilot primary pressure circuit connecting the pilot pump 8 and the remote control valve 5 is connected with a relief valve 9 for determining the maximum pilot pressure and an accumulator 10 for stabilizing the pilot pressure, thereby constituting a hydraulic pilot control unit A. Is done.

  Thus, according to the electric motor drive system in which the pilot pump 8 is driven by the electric motor 7, since the pilot pump 8 can be controlled independently of the engine 1, energy loss can be suppressed.

  In the case of adopting this electric motor drive system, in the known technique disclosed in Patent Document 1, the discharge pressure of the pilot pump 8 is detected by the pressure sensor 11 as shown in FIG. The electric motor 7 is configured to be on / off controlled or feedback controlled so that the target pressure is maintained.

JP 2001-165105 A

  However, according to the above known technique, the pressure sensor 11 for detecting the discharge pressure of the pilot pump 8 must be newly installed, which increases the cost.

  In addition, in the case of on / off control, hysteresis must be provided in the target value in order to ensure the stability of control, resulting in a pressure fluctuation of the hysteresis width. In the case of feedback control, there is a response delay or pressure fluctuation due to gain. Arise. This is disadvantageous in terms of control accuracy.

  Furthermore, since the relief action by the relief valve 9 works when the pressure fluctuation increases, in other words, there is a problem that energy loss still occurs because the construction is based on the relief operation.

  Therefore, the present invention is a construction machine that can reduce the cost by eliminating the need for a pressure sensor, improve the control accuracy, and eliminate the energy loss due to the relief operation while adopting the electric motor drive system in which the pilot pump is driven by the electric motor. A hydraulic control device is provided.

As means for solving the above problems, in the present invention, a prime mover, a main pump driven by the prime mover, a hydraulic actuator driven by pressure oil discharged from the main pump, and operation of the hydraulic actuator are controlled. A pilot control hydraulic control valve, a remote control valve for sending a pilot pressure corresponding to the operation amount of the operating means to the hydraulic control valve, a pilot pump for supplying a pilot primary pressure to the remote control valve, and driving the pilot pump And a control means for controlling the motor, the control means for the motor
Pp = 2π × motor torque ÷ pilot pump capacity
The constant torque control is performed to make the pump pressure Pp of the pilot pump determined in (1) constant .

According to this configuration, the discharge pressure (pump pressure = pilot primary pressure ) P p of the pilot pump can be kept constant.

  Therefore, since no relief operation is performed during normal operation, no energy loss occurs.

  In addition, the pressure sensor required in the known technology is not necessary, and the pressure fluctuation of the hysteresis width in the on / off control, the response delay in the feedback control, and the pressure fluctuation due to the gain are eliminated, and the control accuracy can be improved. .

  In the present invention, a check valve is provided in the pilot primary pressure circuit connecting the pilot pump and the remote control valve, and an accumulator is provided downstream of the check valve, and an operation detection means for detecting whether or not the operation means is operated is provided. It is desirable that the control means is configured so that a torque command for the electric motor is set to 0 when the operation means is neutral (claim 2).

  According to this configuration, since the electric motor stops and the pilot pump stops when the operation means is neutral (non-operating), useless operation is avoided and energy is saved.

  In this case, the pressure in the pilot primary pressure circuit is secured by the accumulator, and the check valve prevents the pilot oil from leaking from the pilot pump.

  As a result, it is possible to prevent a delay due to insufficient pilot primary pressure when the pilot pump is activated.

In the present invention, a relief valve is provided in the pilot primary pressure circuit connecting the pilot pump and the remote control valve, and is obtained from the torque value To commanded to the electric motor and the pilot pump capacity q by (2π × Ts) / q. Pp is the discharge pressure of the pilot pump, and the allowable pressure of the hydraulic pilot control unit consisting of the pilot primary pressure circuit and the hydraulic equipment provided in the same circuit is P1, and the set pressure Ps of the relief valve is
Pp <Ps ≦ Pl
It is desirable to set to (Claim 3).

  According to the present invention, since the relief operation is not performed during the normal operation as described above, a relief valve is theoretically unnecessary.

  However, if the torque control cannot be performed due to a failure of the motor control system and the pressure of the pilot primary pressure circuit rises, there is a risk of damage to the equipment and piping of the hydraulic pilot control unit.

In this respect, the relief valve is provided as described above, and the set pressure Ps is set to Pp <Ps ≦ Pl.
By setting to, damage to equipment including piping of the hydraulic pilot control unit can be prevented.

  Furthermore, in the present invention, it is desirable to provide an emergency switch that permits the operation of the electric motor when the prime mover is stopped, and the control means is configured to operate the electric motor based on the operation of the emergency switch. ).

  According to this configuration, like a shovel, a negative swing brake that releases the brake when pressurized and a holding valve (holding valve) that holds the load on the boom are provided, and these are operated with pilot pressure. Even in situations where the prime mover cannot be operated, such as during maintenance, emergency evacuation, etc., the oil from the pilot pump can operate the hydraulic equipment to release the brake or lower the boom (lower the load). it can.

  On the other hand, in the present invention, a generator motor is connected to the hybrid configuration, that is, the engine as the prime mover, the power battery is charged by the generator action of the generator motor, and the generator motor is driven by the power of the power battery. In the hybrid machine configured to assist the engine by driving as described above, the electric motor that is the driving source of the pilot pump can be driven by the electric power of the power battery or the generator motor.

  According to this configuration, since the power of the power battery and generator motor mounted on the hybrid machine, that is, the power generated using the remaining power of the engine can be used as the power source of the pilot pump motor, an auxiliary battery such as a lead battery There is no need to increase the capacity of the battery as in the case of using the battery, which is advantageous in terms of cost and the like.

  According to the present invention, it is possible to reduce the cost by omitting the pressure sensor while adopting the electric motor drive system, improve the control accuracy, and eliminate the energy loss due to the relief operation.

It is a system configuration figure showing a 1st embodiment of the present invention. It is a system configuration figure showing a 2nd embodiment of the present invention. It is a system block diagram which shows a well-known technique.

  The embodiment is applied to a hybrid excavator.

  In the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 2, the following points are the same as those of the known technique shown in FIG.

  (i) A main pump 22 is connected to an engine 21 as a prime mover, and discharge oil is supplied from the main pump 22 to a hydraulic actuator 24 via a hydraulic pilot type hydraulic control valve 23.

  (ii) A remote control valve (hydraulic pilot valve) 25 is provided, and a pilot pressure corresponding to the amount of operation of the lever 26 as the operating means is sent from the remote control valve 25 to the pilot port of the hydraulic control valve 23, whereby the hydraulic control valve 23 is operated, and the operation of the hydraulic actuator 24 is controlled.

  (iii) A pilot pump 28 is driven by an electric motor (hereinafter referred to as a pilot pump motor) 27, and a pilot primary pressure is supplied from the pilot pump 28 to the remote control valve 25.

  In both the embodiments, as a configuration unique to the hybrid, a generator motor 29 is connected to the engine 21 together with the main pump 22, and the power battery 30 is charged by the generator action of the generator motor 29. The generator motor 29 is configured to assist the engine 21 by performing an electric motor action with 30 electric power.

1st Embodiment (refer FIG. 1)
The generator / motor operation of the generator motor 29 and the charge / discharge operation of the power battery 30 are controlled by a controller 31 and an inverter 32 that constitute control means.

  The pilot pump motor 27 is connected to the power battery 30 via an electric motor controller 33 constituting control means, and is driven by the power battery 30 as a power source, and is controlled by the controller 31 and the electric motor controller 33. .

  On the other hand, a pilot primary pressure circuit connecting the pilot pump 28 and the remote control valve 25 is provided with a relief valve 34, an accumulator 35 for securing a pilot pressure required when the pilot pump is stopped, and the pilot pump 28 on the upstream side of the accumulator 35. A check valve 36 for blocking the flow of pilot oil is provided, and a hydraulic pilot control unit B is configured by these check valves.

  In addition, a pressure sensor 37 for detecting a pilot pressure sent from the remote control valve 25 to the hydraulic control valve 23 is provided as an operation detection means for detecting whether or not the remote control valve 25 is operated, and a signal (operation presence or absence) from the sensor 37 is provided. ) Is sent to the controller 31.

  As a basic action, the controller 31 determines whether or not the remote control valve 25 is operated based on a signal from the pressure sensor 37, and the motor 27 is operated so that the torque of the pilot pump motor 27 is always constant during the operation. Perform constant torque control.

Here, the discharge pressure (pump pressure) Pp of the pilot pump 28 obtained by the constant torque control as described above is assumed that the torque command value for the pilot pump motor 27 is To.
It is determined by Pp = 2π × To ÷ pilot pump capacity.

  That is, by controlling the pilot pump motor 27 at a constant torque, the pilot pump 28 is driven at an arbitrary rotational speed (the rotational speed determined by the target torque) regardless of the engine rotational speed, and the pump pressure (= pilot primary pressure). ) Pp is always constant.

  Accordingly, during normal operation, the relief operation by the relief valve 34 is not performed, and no relief loss occurs.

  In addition, the pressure sensor for detecting the pump pressure, which is necessary in the known technology, is not necessary, and the cost can be reduced.

  Note that a pressure sensor 37 as an operation detecting means is required, but the sensor 37 is originally provided as a standard equipment in the machine for pump control and the like, and this sensor signal is merely used for pilot pump control. Because it is good, it does not increase the cost.

  Further, since there is no pressure fluctuation of the hysteresis width in the on / off control of the known technology, and no response fluctuation or pressure fluctuation due to the gain in the feedback control, the control accuracy can be improved.

  In the embodiment, the torque command sent from the controller 31 to the pilot pump motor 27 is set to 0 when the remote control valve 25 is neutral (not operated).

  According to this configuration, since the pilot pump motor 27 is stopped and the pilot pump 28 is stopped when not operated, useless operation is avoided and energy is saved.

  In this case, the pressure of the pilot primary pressure circuit is secured by the accumulator 35, and the check valve 36 prevents the pilot oil from leaking from the pilot pump 28.

  As a result, it is possible to prevent a delay due to insufficient pilot primary pressure when the pilot pump is activated.

  By the way, since the pump pressure Pp of the pilot pump 28 is always kept constant by constant torque control as described above, the relief valve 34 does not perform a relief operation during normal operation. That is, in theory, the relief valve 34 is unnecessary.

  However, when the torque control cannot be performed due to the failure of the motor control system and the pressure of the pilot primary pressure circuit increases, the equipment and piping of the hydraulic pilot control unit B may be damaged.

Therefore, in the embodiment, a leaf valve 34 is provided, and the set pressure Ps is
Pp <Ps ≦ Pl
Is set to Pl is an allowable pressure of the hydraulic pilot control unit B (a limit pressure that can prevent damage to piping and equipment).

  Thereby, damage to the equipment and piping of the hydraulic pilot control unit B can be prevented.

  In addition, according to the embodiment, the electric power of the power battery 30 mounted on the hybrid machine, that is, the electric power generated using the surplus power of the engine 21 can be used as the power source of the pilot pump motor 27. There is no need to increase the capacity of the battery as in the case of using an auxiliary battery, which is advantageous in terms of cost and the like.

  A configuration may be adopted in which the electric power of the generator motor 29 is used as the power source of the pilot pump motor 27. Even in this case, the same effect as described above can be obtained.

Second embodiment (see FIG. 2)
Only differences from the first embodiment will be described.

  The excavator is provided with a negative swing brake that releases the brake when pressurized and a holding valve (holding valve) that holds the load of the boom cylinder, each of which is operated by pilot pump oil.

  In this case, the engine drive system cannot be operated in a situation where the engine cannot be operated, such as during repair, maintenance, or emergency evacuation.

  In the second embodiment, a measure for this point is taken in addition to the basic configuration of the first embodiment. Here, the holding valve 38 is illustrated, but the same configuration can be adopted for other hydraulic equipment that is operated by pilot oil such as a turning brake.

  A holding valve 38 is provided on the extending side of the boom cylinder 24, which is one of the hydraulic actuators, and the holding valve 38 prevents a natural drop of the boom (load W).

  On the other hand, when the boom remote control valve 25 is operated to lower the boom, the pilot pressure from the boom remote control valve 25 is supplied to the boom control valve in the hydraulic control valve 23, and is also supplied to the holding valve 38 by the holding valve line 39. Is also supplied.

  Thereby, the boom cylinder 24 can be reduced and the load W can be lowered.

  In the second embodiment, an emergency switch 40 is provided, and when the emergency switch 40 is operated with the engine stopped, the pilot pump motor 27 is connected from the controller 31 via the motor controller 33 based on the boom lowering operation. An operation command is issued.

  Accordingly, even when the engine is stopped, if the boom lowering operation is performed after operating the emergency switch 40, the pilot pump motor 27 rotates to drive the pilot pump 28, and the pilot oil is supplied to the holding valve 38. The load W can be lowered by lowering.

  By the way, the present invention is not limited to the hybrid excavator exemplified in the above embodiment, but also to a general hydraulic excavator, an electric excavator using an electric motor as a prime mover, and other construction machines having the same configuration as the excavator. The same can be applied.

  In the case of a machine using an engine as a prime mover, the pilot pump motor 27 is driven by a normal battery such as a lead battery. In the case of an electric machine, it may be driven by the same power source as the motor as the prime mover.

DESCRIPTION OF SYMBOLS 21 Engine 22 Main pump 23 Hydraulic control valve 24 Hydraulic actuator 25 Remote control valve 26 Lever as operation means 27 Pilot pump motor 28 Pilot pump 29 Generator motor 30 Power battery 31 Controller constituting control means 32 Same as inverter 33 Same as motor Controller B Hydraulic pilot control section 34 Relief valve 35 Accumulator 36 Check valve 37 Pressure sensor as operation detection means 40 Emergency switch

Claims (5)

A prime mover, a main pump driven by the prime mover, a hydraulic actuator driven by pressure oil discharged from the main pump, a hydraulic pilot-type hydraulic control valve for controlling the operation of the hydraulic actuator, and an operating means A remote control valve for sending a pilot pressure corresponding to the operation amount to the hydraulic control valve, a pilot pump for supplying the pilot primary pressure to the remote control valve, an electric motor for driving the pilot pump, and a control means for controlling the electric motor The control means includes the motor,
Pp = 2π × motor torque ÷ pilot pump capacity
A hydraulic control device for a construction machine, characterized in that it is configured to perform a constant torque control for making the pump pressure Pp of the pilot pump determined in (1) constant .   The pilot primary pressure circuit connecting the pilot pump and the remote control valve is provided with a check valve, and an accumulator is provided downstream of the check valve, respectively, operation detection means for detecting whether or not the operation means is operated, and the control means includes: 2. The hydraulic control device for a construction machine according to claim 1, wherein a torque command for the electric motor is set to 0 when the operation means is neutral. A pilot primary pressure circuit connecting the pilot pump and the remote control valve is provided with a relief valve, and the discharge pressure of the pilot pump determined by (2π × Ts) / q from the torque value To commanded to the motor and the pilot pump capacity q Pp, where the allowable pressure of the hydraulic pilot control unit composed of the pilot primary pressure circuit and the hydraulic equipment provided in the same circuit is P1, and the set pressure Ps of the relief valve is
Pp <Ps ≦ Pl
The hydraulic control device for a construction machine according to claim 1 or 2, wherein   The emergency switch which permits the action | operation of the said electric motor at the time of the said motor | power_engine stop is provided, The said control means was comprised so that an electric motor might be actuated based on operation of this emergency switch, Any one of Claims 1-3 characterized by the above-mentioned. The hydraulic control device for a construction machine according to claim 1.   The generator motor is connected to the engine as the prime mover, and the power battery is charged by the generator action of the generator motor, and the generator motor is driven as the motor by the power of the power battery to assist the engine. The hydraulic control of the construction machine according to any one of claims 1 to 4, wherein the electric motor that is a driving source of the pilot pump is driven by electric power of the power battery or the generator motor. apparatus.

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