WO2006022043A1

WO2006022043A1 - Hydraulic pressure drive circuit

Info

Publication number: WO2006022043A1
Application number: PCT/JP2005/004930
Authority: WO
Inventors: Masatoshi Miki; Hiroshi Sato; Manabu Tamura; Nobuaki Matoba
Original assignee: Shin Caterpillar Mitsubishi Ltd.
Priority date: 2004-08-26
Filing date: 2005-03-18
Publication date: 2006-03-02
Also published as: JP2006064071A; JP4291759B2

Abstract

A hydraulic pressure drive circuit capable of efficiently recovering energy. A hydraulic oil as a fluid is fed to an actuator (41) by a pump (23) driven by an engine (21) through a drive device (22) after being controlled by a control valve device (25), and the fluid oil returned from the actuator (41) is discharged into a tank (24). A regenerative motor (44) recovering the excess pressure energy of the hydraulic oil returned from the actuator (41) to the tank (24) and regenerating it on the drive device (22) is direct-coupled to the pump (23). The fluid return side pressure and the fluid entering side pressure of the actuator (41) are detected by pressure sensors (48) and (49), a selector valve device (55) selectively controls so that when the fluid return side pressure is higher than the fluid entering side pressure and higher than a set value, the bottom side (41b) of the actuator (41) is allowed to communicate with the regenerative motor (44) by a controller (61), and when it is lower, the bottom side (41b) of the actuator (41) is allowed to communicate with the tank (24).

Description

Specification

Fluid pressure drive circuit

Technical field

[0001] The present invention relates to a fluid pressure drive circuit having an energy regeneration function.

Background art

As shown in FIG. 8, a hydraulic excavator as a work machine is provided with an upper swinging body 12 that can swing with respect to a lower traveling body 11, and the upper swinging body 12 is operated together with a cap 13 and a power unit 14. A device 15 is mounted, and the working device 15 is supported by a pivot 16 that is pivoted up and down by a boom cylinder 16c on an upper swing body 12, and is rotated by a stick cylinder 17c at the tip of the boom 16. The stick 17 is pivotally supported, and the packet 18 rotated by the bucket cylinder 18c via the linkage 19 is pivotally supported at the tip of the stick 17.

[0003] Hybrid machines using the power unit 14 are also being advanced in work machines such as hydraulic excavators. Energy saving can be achieved as an expected effect of this hybrid.

[0004] As a prior art related to this, for example, during the boom lowering operation of a hydraulic excavator, high pressure cylinder return oil generated at the bottom side of the boom cylinder 16c is collected and accumulated in an accumulator for further energy saving. A pressure oil recovery and reuse system is described (for example, see Patent Document 1).

[0005] The one disclosed in Patent Document 1 uses an accumulator as a means for storing pressure energy. Therefore, there is a drawback that the energy is reduced in a short time if the stored energy is not used. In addition, there is a problem that the storage amount of the accumulator is smaller than the required amount, and there is also a problem that a large accumulator is required to store a large amount of energy.

[0006] On the other hand, there is one that can store large energy in a relatively small volume by converting hydraulic energy into electric energy and storing it in a battery (for example, Patent Documents 2, 3, 4 and 5). Patent Document 1: Japanese Patent Publication No. 3-33922 (page 2-4, Fig. 1 2)

Patent Document 2: Japanese Unexamined Patent Publication No. 2000-136806 (Pages 8-9, Fig. 1)

Patent Document 3: Japanese Patent Laid-Open No. 2002-242234 (Page 45, Fig. 1)

Patent Document 4: JP 2002-322682 A (page 3-4, Fig. 1-2)

Patent Document 5: WO0lZ88381 (Pages 27-31, Fig. 4)

Disclosure of the invention

Problems to be solved by the invention

[0007] These conventional techniques may alternately recover and regenerate hydraulic energy and attempt to regenerate energy without waste. In some cases, the hydraulic energy cannot be recovered. In such a case, conversely, the hydraulic energy recovery means becomes a load and energy loss occurs, and energy recovery cannot be performed efficiently.

[0008] The present invention has been made in view of these points, and an object of the present invention is to provide a fluid pressure drive circuit capable of efficiently recovering energy.

Means for solving the problem

[0009] The invention according to claim 1 includes a drive device for driving the pump, and the fluid pumped up from the tank by the pump and supplied to the actuator, and the fluid returned from the actuator is supplied into the tank. Control valve device that discharges, regenerative motor that recovers excess pressure energy of the fluid that is returned to the actuator tank and regenerates it to the drive device, and pressure detection that detects the fluid return side pressure and the fluid entry side pressure of the actuator Switch valve device that connects the fluid return side of the actuator and the actuator to either the regenerative motor or the tank, and the fluid return side pressure of the actuator detected by the pressure detection device is higher than the fluid inlet side pressure and the set value For higher pressures, the fluid return side of the actuator is connected to the regenerative motor, and the fluid return side pressure is lower than the fluid entry side pressure. For, or when a lower pressure than the Jo Tokoro set value is a fluid pressure drive circuit switching valve device equipped with a controller for switching control so as to communicate with the tank fluid return side of Akuchiyueta.

[0010] Then, when the surplus pressure energy of the actuator is recovered by the regenerative motor and regenerated to the drive device, the fluid return side pressure of the actuator detected by the pressure detection device is higher than the fluid entering side pressure and is a set value. For higher pressures, the controller switches By controlling the device to connect the fluid return side of the actuator to the regenerative motor, the fluid return side force pressure energy of the actuator is recovered, while the fluid return side pressure is lower than the fluid entry side pressure, or If the pressure energy cannot be taken out when the pressure is lower than the preset value, the regenerative motor force is also disconnected from the fluid return side of the actuator by the switching valve device so that the regenerative motor is communicated. It is possible to reduce the energy loss that occurs when the motor becomes a load on the drive device, and it is possible to efficiently recover the energy and further save energy.

[0011] According to the invention described in claim 2, the driving device in the fluid pressure driving circuit described in claim 1 includes a generator connected to the engine, an electrical connection to the generator, and a mechanism connected to the pump. A motor and a motor generator that function as a motor and a generator, and a capacitor that is connected to the generator and the motor generator through a converter. The pump and the regenerative motor are each for variable capacity. The controller has a swash plate and controls the rotation speed of the regenerative motor and pump by controlling the opening degree of the switching valve device and the rotation speed of the motor generator so that the commanded actuator speed can be obtained. At the same time, it controls the tilt angle of these swash plates.

[0012] In a series-type drive device in which an engine, a generator, and a motor generator are sequentially connected to a pump, regeneration is controlled by controlling the opening degree of the switching valve device and the rotation speed of the motor generator. It is possible to obtain the commanded actuator speed by controlling the rotational speed of the motor and pump and by controlling the tilt angle of these swash plates.

[0013] In the invention of claim 3, the pump and the regenerative motor in the fluid pressure drive circuit of claim 1 each have a variable capacity swash plate, and the drive device is provided between the engine and the pump. An intervening gearbox, a motor generator connected to the pump in parallel with the engine via the gearbox and functioning as a motor and a generator, and a capacitor connected to the motor generator via a comparator. The controller controls the capacity of the regenerative motor and the pump so as to obtain the commanded actuator speed by controlling the regenerative motor and the swash plate of the pump.

[0014] Then, in a parallel type driving device in which the engine and the motor generator are connected in parallel to the pump via a gear box, the regenerative motor and the swash plate of the pump are controlled. By controlling these capacities, it is possible to obtain the commanded actuator speed.

[0015] The invention of claim 4 comprises a control valve device force in the fluid pressure drive circuit according to any one of claims 1 to 3, a plurality of control valves of a spool structure for controlling a plurality of actuators, The plurality of control valves each have a center passage connected in tandem between the pump and the tank, and the switching valve device is connected to the drain port of the downstream control valve.

[0016] A drive device and a regenerative motor can be shared with a plurality of actuators controlled by a plurality of control valves, and the center binos passages of the plurality of control valves are connected in tandem. If the excess pressure energy discharged from the downstream side actuator after the upstream side actuator is activated with priority, the switching valve device connected to the drain port of the downstream side control valve Thus, the excess pressure energy is regenerated to the pump and the drive device through the regenerative motor.

[0017] In the invention according to claim 5, the switching valve device in the fluid pressure drive circuit according to any one of claims 1 to 4 includes an electromagnetic proportional valve, and the fluid return side of the actuator Since this switching valve device is an electromagnetic proportional valve, a meter-out control function suitable for controlling the operating speed of the actuator on which the load acts can be obtained.

The invention's effect

[0018] According to the invention of claim 1, when the surplus pressure energy of the actuator is recovered by the regenerative motor and regenerated to the drive device, the fluid return side pressure of the actuator detected by the pressure detection device is When the pressure is higher than the fluid entry side pressure and higher than the set value, the controller controls the switching valve device to connect the fluid return side of the actuator to the regenerative motor, thereby recovering the pressure energy from the fluid return side of the actuator. On the other hand, if the pressure energy cannot be taken out when the pressure on the fluid return side is lower than the pressure on the fluid input side or the pressure is lower than the predetermined set value, the switching valve device can be used to return the fluid to the fluid return side of the actuator. Since the regenerative motor force was also disconnected, it was made to communicate with the tank.

In addition, energy loss that occurs when the regenerative motor becomes a load on the drive device can be reduced, energy recovery can be performed efficiently, and energy saving can be further achieved. [0019] According to the invention of claim 2, in the series type driving device in which the engine, the generator, and the motor generator are sequentially connected to the pump, the opening degree of the switching valve device and the electric generator By controlling the rotational speed, the rotational speeds of the regenerative motor and pump can be controlled, and the tilt angle of these swash plates can be controlled to obtain the commanded actuator speed.

[0020] According to the invention of claim 3, in the parallel type driving device in which the engine and the electric generator are connected in parallel to the pump via the gear box, the regenerative motor and the swash plate of the pump are controlled. By doing so, these capacities can be controlled to obtain the commanded actuator speed.

[0021] According to the invention of claim 4, the drive device and the regenerative motor can be shared for the plurality of actuators controlled by the plurality of control valves, and the center binos of the plurality of control valves By connecting the passages in tandem, the upstream side actuator is operated with priority, and if the excess pressure energy discharged from the downstream side is sufficiently high, the drain port of the downstream control valve The surplus pressure energy can be regenerated to the pump and the drive device through the regenerative motor by the switching valve device connected to.

[0022] According to the invention described in claim 5, since the switching valve device on the fluid return side of the actuator is an electromagnetic proportional valve, a meter-out control function suitable for controlling the operating speed of the actuator on which the load acts is provided. Obtainable.

Brief Description of Drawings

FIG. 1 is a circuit diagram showing a first embodiment of a fluid pressure drive circuit according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of a fluid pressure drive circuit according to the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of a fluid pressure drive circuit according to the present invention.

FIG. 4 is a circuit diagram showing a fourth embodiment of a fluid pressure drive circuit according to the present invention.

FIG. 5 is a circuit diagram showing a fifth embodiment of a fluid pressure drive circuit according to the present invention.

FIG. 6 is a circuit diagram showing a sixth embodiment of a fluid pressure drive circuit according to the present invention.

FIG. 7 is a configuration diagram showing another example of the driving device of the fluid pressure driving circuit.

FIG. 8 is a side view of the excavator. Explanation of symbols

[0024] 21 engine

22, 22a Drive unit

23 Pump

24 tanks

25 Control valve device

26, 45 Swash plate

31 Generator

32, 92 Motor generator

33, 93 Converter

34, 94 battery

38, 39, 56, 57 Solenoid proportional valve

41, 81 Actuator

44 Regenerative motor

48, 49 Pressure sensor as pressure detector

55 Switching valve device

61 controller

67, 76, 77 Proportional solenoid valve

71, 82 Control valve

73 Drain port

83, 84 Center bypass passage

91 gearbox

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] Hereinafter, the present invention is shown in the first embodiment shown in FIG. 1, the second embodiment shown in FIG. 2, the third embodiment shown in FIG. 3, and FIG. The fourth embodiment described above, the fifth embodiment shown in FIG. 5, the sixth embodiment shown in FIG. 6, and a modification of the drive device shown in FIG. 7 will be described.

First, the first embodiment shown in FIG. 1 will be described. [0027] A pump 23 is connected to the engine 21 via a drive device 22. The drive device 22 drives the pump 23 in response to the rotation of the engine 21, and controls the hydraulic oil as fluid in the tank 24 with a control valve device. Supply pressure to 25. The pump 23 is a hydraulic pump having a swash plate 26 for variable capacity.

[0028] In the drive unit 22, a generator 31 is connected to the engine 21, and an electric motor mechanically directly connected to the pump 23 and a motor generator 32 functioning as a generator are electrically connected to the generator 31. In this series system, a battery 34 is connected to a generator 31 and a motor generator 32 via a converter 33.

A control valve device 25 is connected to the discharge passage 35 of the pump 23. This control valve device 25 is a bridge circuit by means of four solenoid proportional valves 36, 37, 38, 39 that can adjust only the opening between the discharge passage 35 of the pump 23 and the tank 24 according to the electrical signal. Is formed.

The four proportional solenoid valves 36, 37, 38, 39 constituting this control valve device 25 supply the hydraulic oil pumped from the tank 24 by the pump 23 to the actuator 41 by controlling the direction and flow rate. At the same time, the hydraulic oil returned from the actuator 41 is discharged into the tank 24. The actuator 41 is, for example, a boom cylinder 16c shown in FIG.

A relief valve 42 and an unload valve 43 are connected to the discharge passage 35 of the pump 23. The relief valve 42 acts as a safety valve for setting pressure, and the unload valve 43 has a pressure releasing action that prevents high pressure from being generated by the minimum discharge flow rate of the pump 23 when the actuator 41 is not driven.

The pump 23 is directly connected to a regenerative motor 44 that recovers excess pressure energy of high-pressure oil returned to the actuator 41 force tank 24 and regenerates it to the drive device 22. The regenerative motor 44 is a hydraulic motor having a variable capacity swash plate 45 capable of setting the minimum flow rate to almost zero.

[0033] The bottom side passage 46 and the rod side passage 47 of the actuator 41 include a pressure on the bottom side 41b as the fluid return side of the actuator 41, that is, a bottom side pressure as the fluid return side pressure, and a fluid entry side of the actuator 41. Pressure sensors 48 and 49 as pressure detecting devices for detecting the pressure on the rod side 41r of the rod, that is, the pressure on the rod side as the fluid containing pressure Relief valves 51 and 52 for setting the actuator pressure and check valves 53 and 54 for make-up are connected to each other.

[0034] A switching valve device 55 is provided to communicate the bottom side 41b as the fluid return side of the actuator 41 with one of the regenerative motor 44 and the tank 24. This switching valve device 55 has a bridge circuit formed by four electromagnetic proportional valves 38, 39, 56, and 57 that can adjust only the opening degree that opens according to an electric signal between the regenerative motor 44 and the tank 24. It is.

Of these, the two electromagnetic proportional valves 38, 39 serve as the control valve device 25 and the switching valve device 55, and the output sides of these electromagnetic proportional valves 38, 39 are connected to the tank 24. The output side of the other two electromagnetic proportional valves 56 and 57 are joined together by a regenerative passage 58, a regenerative motor 44, a relief valve 59 for setting the regenerative pressure, and a check valve 60 for regenerative passage make-up. It is connected to the.

[0036] When the negative pressure is likely to be generated in the regenerative passage 58 or the like because of the check valve 60, for example, when the regenerative motor 44 is rotated as a load of the pump 23 in the regenerative state, the tank 24 By sucking the hydraulic oil in the regenerative passage 58 through the check valve 60, it is possible to prevent negative pressure from being generated in the regenerative passage 58 or the like and an increase in pump load.

[0037] The pressure sensors 48 and 49 for detecting the fluid return side pressure and the fluid entering side pressure of the actuator 41 are connected to the input side of the controller 61, and the output side of the controller 61 is connected to the electromagnetic proportional valve 36. , 37, 38, 39, 56, 57 etc.

[0038] When the weight or load is acting on the actuator 41, the fluid return side pressure of the actuator 41 may be higher than the fluid entry side pressure. The detected fluid return side pressure on the bottom side 41b of the actuator 41 is higher than the fluid entry side pressure on the rod side 41r of the actuator 41 detected by the other pressure sensor 49 and higher than a predetermined set value. In this case, the bottom side 41b of the actuator 41 is connected to the regenerative motor 44, and the bottom side pressure force of the actuator 41 detected by one pressure sensor 48 The rod side of the actuator 41 detected by the other pressure sensor 49 If the pressure is lower than the pressure, or if the pressure is lower than the preset value, the bottom 41b of the actuator 41 is The solenoid proportional valves 38, 39, 56, and 57 of the switching valve device 55 are controlled so as to communicate with 24.

That is, the controller 61 includes an actuator detected by the one pressure sensor 48. Pressure pressure on the fluid return side from the bottom side 41b of 41 When the pressure on the rod side 41r of the actuator 41 detected by the other pressure sensor 49 is higher than the pressure on the fluid entering side and higher than the set pressure The high pressure oil from the bottom side 41b of the actuator 41 is pressurized and supplied to the regenerative motor 44 through the electromagnetic proportional valve 56 and the regenerative passage 58, so that the energy of the high pressure oil is regenerated instead of the rotational torque energy of the regenerative motor 44. Let A part of the regenerated energy is consumed by the pump 23 directly connected to the regenerative motor 44, and the surplus is converted into electric energy by the power generation action of the motor generator 32, and the capacitor 34 is charged.

[0040] On the other hand, if the pressure on the fluid return side from the bottom side 41b of the actuator 41 is lower than the pressure on the fluid entering side, or lower than the predetermined set pressure, the energy is supplied to the regenerative motor 44. In this case, the controller 61 opens the solenoid proportional valve 38 so that the return oil from the bottom side 41b of the actuator 41 flows into the tank 24.

[0041] In this way, the controller 61 determines whether or not energy regeneration is performed by the regenerative motor 44 based on the values of the left and right pressure sensors 48 and 49. When energy regeneration is not performed, the actuator 41 returns the return oil. Is not supplied to the regenerative motor 44.

[0042] Further, the controller 61 controls the rotational speed of the electric generator 32 and the opening degree of the electromagnetic proportional valve 56 of the switching valve device 55 so that the commanded actuator speed can be obtained. In addition, the rotational speed of the regenerative motor 44 is controlled, and the tilt angle of the swash plates 26 and 45 of the pump 23 and the regenerative motor 44 is controlled via a regulator not shown by an electromagnetic proportional valve not shown.

In the drawing, for example, an actuator 41 is connected by a pump 23 connected to a boom motor generator 32 of a hydraulic excavator, a control valve device 25 connected to the pump 23, and a regenerative motor 44. Driving force Similarly, traveling system, turning system, stick system or packet system not shown ヽ Other pumps connected to other motor generators, other control valve devices connected to this pump, etc. The other regenerative motor also drives other actuators, and the electric power of the common generator 31 and the accumulator 34 and the regenerated electric power are supplied to these motor drives.

Next, the function and effect of the first embodiment will be described.

[0045] The case where the actuator 41 is the boom cylinder 16c shown in FIG. 8 will be described. . In such an actuator 41, the weight of the work device 15 acts, a high pressure stands on the bottom side 41b, and the rod side 41r has a low pressure.

[0046] When the boom lowering operation is performed, the high pressure oil on the bottom side 41b of the actuator 41 flows to the regenerative motor 44 by electromagnetically driving and opening the electromagnetic proportional valve 56. The energy of the high pressure oil causes the regenerative motor 44 to Drive torque is generated and the rotational speed increases. In other words, the energy of high-pressure oil is regenerated.

When the regenerative motor 44 enters the regenerative state in this way, the regenerative power input to the regenerative motor 44 is converted into electric energy by the power generation action of the directly connected motor generator 32 and stored in the capacitor 34. .

[0048] When the discharge flow rate from the pump 23 directly connected to the regenerative motor 44 increases and at the same time the electromagnetic proportional valve 37 is electromagnetically driven and opened, the pump discharge pressure oil flows to the rod side 41r of the actuator 41. At this time, the proportional function of the electromagnetic proportional valves 37 and 56 is provided by a proportional function, so that the shock at the start can be alleviated.

[0049] Further, since the proportional solenoid valve 56 is connected to the bottom side 41b of the actuator 41, a meter-out control function suitable for controlling the operating speed of the actuator 41 operated by the load can be obtained.

[0050] On the other hand, a method of starting the motor generator 32 until sufficient regenerative power can be obtained, that is, a method of supplying electric power may be employed. In a state where sufficient regenerative power is obtained, the motor generator 32 is caused to generate power.

The actuator 41 is driven by a speed command from the operator's operation lever. By this speed command, the rotation speed of the regenerative motor 44 is controlled to be proportional to the speed command during the above regeneration. Here, the swash plates 26 and 45 of the pump 23 and the regenerative motor 44 are used for adjustment. The rotational speed to be controlled may cause an error with respect to the speed command, and fine adjustment of the flow rate is required. In this embodiment, the regenerative motor 44 and the pump 23 are provided with the swash plates 45 and 26 for fine adjustment of the flow rate, but only one of them can be controlled.

[0052] In general, the power of the pump 23 is smaller than the power regenerated by the regenerative motor 44. Therefore, the surplus power is regenerated to the electric energy by the power generation action of the motor generator 32 and is supplied to the battery 34 via the converter 33. Charged. [0053] In order to detect that a pressure higher than the rod side 41r is standing on the bottom side 41b of the actuator 41, two pressure sensors 48 and 49 are used. If the rod side 41r is in a state where the high pressure is generated on the bottom side 41b of the actuator 41 and the rod side 41r is at a low pressure, and the pressure pressure on the bottom side is greater than the preset pressure value, it is determined that the actuator is in a regenerative state. Then, the high pressure oil is guided to the regenerative motor 44.

[0054] Therefore, in the other stick cylinder 17c and bucket cylinder 18c, the fluid return side pressure of the actuator 41 is higher than the fluid entry side pressure and higher than the set value when weight and load are applied. Therefore, the regenerative action of guiding the high pressure oil on the bottom side 41b of the actuator 41 to the regenerative motor 44 can be applied.

[0055] On the other hand, when the bottom side 41b has a lower pressure than the rod side 41r, or a pressure lower than a predetermined set value, sufficient regenerative power cannot be obtained, so the low pressure on the bottom side 41b of the actuator 41 is low. The oil is not regenerated and is discharged to the tank 24 through the electromagnetic proportional valve 38 that is electromagnetically driven in the open state. Further, the rotational speed of the pump 23 is controlled in proportion to the speed command at the time of the regeneration by the speed command to the motor generator 32.

[0056] For the work corresponding to this, in the boom cylinder 16c, even after the packet 18 is put on the ground, the boom cylinder 16c is contracted and operated to lift the airframe. At this time, the bottom side 41b of the actuator 41 has a low pressure, and the rod side 41r requires a high pressure. The detection of this state can be limited to the case where the pressure sensors 48 and 49 are used and the pressure sensor 49 on the rod side 41r is high pressure and the pressure sensor 48 on the bottom side 41b is low pressure.

[0057] In this way, when the surplus pressure energy of the actuator 41 is recovered by the regenerative motor 44 and regenerated to the pump 23 or the driving device 22, the pressure on the fluid return side of the actuator 41 detected by the pressure sensors 48, 49 is detected. When the pressure is higher than the fluid entry side pressure and higher than the set value, the controller 61 controls the switching valve device 55 so that the bottom side 41b of the actuator 41 communicates with the regenerative motor 44, so that the bottom side 41b of the actuator 41 On the other hand, when the fluid return side pressure is lower than the fluid entry side pressure, or lower than the predetermined set value, that is, when the pressure energy cannot be extracted, the switching valve device Since the bottom side 41b of the actuator 41 is disconnected by the regenerative motor 44 force by 55 and communicated with the tank 24, the regenerative motor 44 And the dynamic device 22 go-between load and In this case, energy loss that occurs can be reduced, energy recovery can be performed efficiently, and energy saving can be further achieved.

[0058] Further, in the series-type drive device 22 in which the engine 21, the generator 31 and the motor generator 32 are sequentially connected to the pump 23, the opening of the electromagnetic proportional valve 56 and the motor generator 32 By controlling the rotational speed, the rotational speeds of the regenerative motor 44 and the pump 23 can be controlled to obtain the commanded actuator speed.

[0059] As described above, a regenerative circuit is provided, and hydraulic energy is regenerated as electric energy, and is directly or temporarily charged in the capacitor 34 and then supplied to the drive system of another actuator as necessary, thereby saving power. It has the effect of reducing harmful emissions by using energy and downsizing the engine 21.

Next, the second embodiment shown in FIG. 2 will be described. The same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Only differences from the first embodiment will be described.

[0061] The control valve device 25 forms a bridge circuit between the pump 23 and the tank 24 by four electromagnetic proportional valves 36, 37, 38, 39 that can adjust only the opening degree that opens in accordance with an electric signal. The force switching valve device 55 is similar to that shown in FIG. 1 in that the return passage 65 connected to the fluid discharge section 64 of the bridge circuit is connected to the electrical signal from the tank passage 66 to the tank 24. Accordingly, an electromagnetic proportional valve 67 that switches to the regenerative passage 58 leading to the regenerative motor 44 is provided.Instead of the electromagnetic proportional valves 38, 39, 56, and 57 shown in FIG. Connecting.

[0062] When high pressure is generated on the bottom side 41b of the actuator 41 and the high pressure oil is regenerated, the electromagnetic proportional valves 38 and 67 are opened to supply the high pressure oil to the regenerative motor 44.

Next, the function and effect of the second embodiment will be described. Differences from the first embodiment are as follows.

[0064] The high pressure oil on the bottom side 41b of the actuator 41 flows to the regenerative motor 44 by opening the electromagnetic proportional valves 38 and 67 by electromagnetic driving, and a driving torque is generated in the regenerative motor 44 by the energy of this high pressure oil. Then the rotation speed increases. In other words, the energy of high-pressure oil is regenerated.

[0065] On the other hand, when the bottom side 41b has a lower pressure than the rod side 41r, or from a predetermined set value. When the pressure becomes low, sufficient regenerative power cannot be obtained, so the low-pressure oil on the bottom side 41b of the actuator 41 is not regenerated and passes through the electromagnetic proportional valve 38 that is electromagnetically driven to the open state. It is discharged to tank 24 from solenoid proportional valve 67.

Next, the third embodiment shown in FIG. 3 will be described. The same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Only differences from the first embodiment will be described.

[0067] The control valve device 25 integrates the functions of the electromagnetic proportional valves 36, 37, 38, and 39 shown in FIG. 1 into a control valve 71 having a spool structure having at least four ports.

[0068] This control valve 71 provides the unloading function shown in FIG. 1 by providing an internal passage 72 through which hydraulic fluid supplied from the pump 23 flows to the tank 24 when the spool is in the neutral position. The unloading valve 43 possessed can be omitted.

[0069] Further, the switching valve device 55 connects the return passage 65 connected to the drain port 73 of the control valve 71 from the tank passage 66 to the tank 24 to the regenerative passage to the regenerative motor 44 in response to an electric signal.

An electromagnetic proportional valve 67 for switching to 58 is provided, and this proportional solenoid valve 67 is connected instead of the solenoid proportional valves 38, 39, 56, 57 shown in FIG.

This electromagnetic proportional valve 67 is used when the pressure on the bottom side 41b of the actuator 41 is low, that is,

When the boom is raised and the aircraft is lifted, the loss increases when the return oil is passed through the regenerative motor 44. Therefore, the structure directly returns to the tank 24.

Next, the function and effect of the third embodiment will be described. Differences from the first embodiment are as follows.

[0072] The high pressure oil on the bottom side 41b of the actuator 41 electromagnetically drives the control valve 71 to switch it to the left position, and at the same time electromagnetically drives the electromagnetic proportional valve 67 of the switching valve device 55, and sets the return path 65 to the tank. By switching from the passage 66 to the regenerative passage 58, high-pressure oil flows into the regenerative motor 44, and drive torque is generated in the regenerative motor 44 by the energy of this high-pressure oil, and the rotational speed of the pump 23 increases. That is, the energy of the high pressure oil is regenerated.

[0073] The discharge passage 35 on the pump side and the return passage 65 on the tank side of the control valve device 25 have a structure of an internal passage 72 that communicates when neutral, and the pressure oil of the pump 23 flows to the tank 24 when neutral. In addition, the minimum pump flow rate at neutrality will prevent high pressure from standing. [0074] On the other hand, if the bottom side 41b of the actuator 41 is lower in pressure than the rod side 41r, or if the pressure is lower than a predetermined set value, sufficient regenerative power cannot be obtained. The oil is not regenerated and is discharged to the tank 24 through the non-excited electromagnetic proportional valve 67.

[0075] Since the solenoid proportional valve 67 is connected to the drain port 73 of the control valve 71 communicating with the bottom side 41b of the actuator 41, meter-out control suitable for controlling the operating speed of the actuator 41 on which the load acts Function is obtained.

Next, the fourth embodiment shown in FIG. 4 will be described. The same parts as those in the embodiment shown in FIGS. 1 and 3 are denoted by the same reference numerals, description thereof is omitted, and only the differences from those embodiments will be described.

[0077] As the control valve device 25, instead of the electromagnetic proportional valves 36, 37, 38, 39 shown in FIG. 1, a control valve 71 having a spool structure is provided. Since the discharge passage 35 and the return passage 65 are not in communication, an unload valve 43 having an unload function is provided for the discharge passage 35 from the pump 23 to the control valve 71.

[0078] The switching valve device 55 uses a return passage 65 connected to the drain port 73 of the control valve 71 instead of the electromagnetic proportional valves 38, 39, 56, 57 shown in FIG. An electromagnetic proportional valve 67 that switches from the passage 66 to the regenerative passage 58 to the regenerative motor 44 according to the electric signal is provided.

[0079] When the pressure on the bottom side 41b of the actuator 41 is low, as in the boom cylinder 16c when the boom is raised and the body is lifted, the electromagnetic proportional valve 67 uses the return oil from the bottom side 41b to regenerate the motor. Since the loss increases when passing through 44, the structure directly returns to the tank 24. In this case, a take-out control function suitable for controlling the operating speed of the actuator 41 to which the load acts is necessary. Use proportional valve 67.

Next, the function and effect of the fourth embodiment will be described. Differences from the first embodiment are as follows.

[0081] When high pressure oil is generated on the bottom side 41b of the actuator 41, the control valve 71 is electromagnetically driven to switch to the left position, and at the same time, the switching valve device 55 is electromagnetically driven to switch to the regenerative passage 58. The high pressure oil generated at the bottom 41b of the actuator 41 High-pressure oil flows into the motor 44, and the drive torque is generated in the regenerative motor 44 due to the energy of this high-pressure oil, and the rotation speed increases. That is, the energy of the high-pressure oil is regenerated in the pump 23 and the drive device 22.

[0082] On the other hand, when the bottom side 41b has a lower pressure than the rod side 41r, or a pressure lower than a predetermined set value, sufficient regenerative power cannot be obtained, so the low pressure on the bottom side 41b of the actuator 41 The oil is not regenerated and is discharged to the tank 24 from the non-excited solenoid proportional valve 67.

Next, the fifth embodiment shown in FIG. 5 will be described. The same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Only differences from the first embodiment will be described.

The control valve device 25 includes a spool-structured control valve 71 instead of the electromagnetic proportional valves 36, 37, 38, 39 shown in FIG.

[0085] Further, the switching valve device 55 has an electric signal for the bottom passage 46 to the control valve 71 force actuator 41 instead of the electromagnetic proportional valves 38, 39, 56, 57 shown in FIG. A plurality of proportional solenoid valves 76, 77 that can be adjusted only in accordance with the opening degree are provided.

That is, the switching valve device 55 branches off from the bottom side passage 46 and the one electromagnetic proportional valve 76 interposed in the bottom side passage 46 communicating the control valve 71 and the bottom side 41b of the actuator 41. The other electromagnetic proportional valve 77 interposed in the regenerative passage 58 communicating with the regenerative motor 44 is provided.

Next, the function and effect of the fifth embodiment will be described. Differences from the first embodiment are as follows.

[0088] When high pressure oil is generated on the bottom side 41b of the actuator 41, the control valve device 25 is electromagnetically driven to switch to the left position, and the electromagnetic proportional valve 77 is electromagnetically driven to open. By switching the bottom side 41b to the regenerative passage 58, the high pressure oil on the bottom side 41b flows into the regenerative motor 44, and the driving torque is generated in the regenerative motor 44 by the energy of this high pressure oil, and the rotational speed increases. That is, the energy of the high pressure oil is regenerated in the pump 23 and the drive device 22. At this time, the electromagnetic proportional valve 76 is closed in a non-excited state, and high pressure oil does not flow into the control valve device 25. [0089] On the other hand, when the bottom side 41b of the actuator 41 is at a lower pressure than the rod side 41r, or when the pressure is lower than a predetermined set value, sufficient regenerative power cannot be obtained and the control valve does not regenerate. At the same time as the device 25 is electromagnetically driven to the left position, the electromagnetic proportional valve 76 is electromagnetically driven, and the low pressure oil on the bottom side 41b of the actuator 41 is discharged to the tank 24 through the electromagnetic proportional valve 76. At this time, the solenoid proportional valve 77 is in a non-excited state, and high pressure oil does not flow into the regenerative motor 44.

Next, the sixth embodiment shown in FIG. 6 will be described. The same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Only differences from the first embodiment will be described.

[0091] The control valve device 25 includes a plurality of control valves 71, 82 having a spool structure for controlling the plurality of actuators 41, 81 in place of the electromagnetic proportional valves 36, 37, 38, 39 shown in FIG. These control valves 71 and 82 have center bypass passages 83 and 84 connected in tandem between the pump 23 and the tank 24, respectively.

In addition, the switching valve device 55 is connected to a drain port 73 of a control valve 71 arranged on the downstream side, and a return passage 65 connected to the drain port 73 is connected to the tank 24 from a tank passage 66. It is equipped with an electromagnetic proportional valve 67 that switches to the regenerative passage 58 to the regenerative motor 44 according to the electrical signal, and instead of the electromagnetic proportional valve 38, 39, 56, 57 shown in Fig. 1, this electromagnetic proportional valve 67 Is installed.

[0093] When the pressure on the bottom side 41b of the actuator 41 is low, as in the boom cylinder 16c when the boom is raised and the aircraft is lifted, the electromagnetic proportional valve 67 uses the return oil from the bottom side 41b as a regenerative motor. Since the loss increases when passing through 44, the structure directly returns to the tank 24. In this case, a take-out control function suitable for controlling the operating speed of the actuator 41 to which the load acts is necessary. Use proportional valve 67.

[0094] Since the control valves 82 and 71 have the center bypass passages 83 and 84 through which the pressure oil from the pump 23 flows to the tank 24, the unload valve of the unload function can be omitted.

Further, on the upstream side of the control valve 71, another control valve 82 having a center bypass passage 83 and driving another actuator 81 is provided, and high-pressure oil from the pump 23 is supplied to the control valve 82. To the pump port 85 of the control valve 71 via the center bypass passage 83 of A tandem circuit connected to supply.

[0096] Thus, when the drive device 22 and the energy recovery regenerative motor 44 are shared by one actuator circuit and another actuator circuit (especially the traveling system), the upstream side of the one actuator is used. Further, another actuator circuit is provided to connect the center bypass passages 83 and 84 to each other.

Next, the function and effect of the sixth embodiment will be described. Differences from the first embodiment are as follows.

[0098] When high pressure oil is generated on the bottom side 41b of the actuator 41, the first control valve 71 is electromagnetically driven to switch to the left position, and at the same time, the electromagnetic proportional valve 67 of the switching valve device 55 is electromagnetically driven. The high pressure oil flows into the regeneration motor 44 by switching the return passage 65 connected to the drain port 73 of the control valve 71 from the tank passage 66 to the tank 24 to the regeneration passage 58 in response to an electrical signal. Due to the energy of the high-pressure oil, a driving torque is generated in the regenerative motor 44, and the rotational speed of the pump 23 increases. In other words, the energy of high-pressure oil is regenerated.

[0099] On the other hand, if the bottom side 41b of the actuator 41 is at a lower pressure than the rod side 41r, or if the pressure is lower than a predetermined set value, sufficient regenerative power cannot be obtained. The oil is not regenerated and is discharged to the tank 24 from the non-excited solenoid proportional valve 67.

[0100] When one control valve 71 that drives one actuator 41 and another control valve 82 that drives another actuator 81 are operated simultaneously, a part of the pressure oil is the other first. The other control oil flows from the control valve 82 to the other actuator 81, and the other pressure oil flows from the control valve 71 to the actuator 41.

[0101] At this time, when the speed of the other actuator 81 is increased, the opening of the control valve 82 is increased, and when the speed of the actuator 41 is increased, the opening of one control valve 71 is increased. Reduce the opening of the other control valve 82.

[0102] According to this embodiment, the drive device 22 and the regenerative motor 44 can be shared for the plurality of actuators 41, 81 controlled by the plurality of control valves 71, 82. By connecting the center bypass passages 83 and 84 of the control valves 82 and 71 in tandem, the upstream actuator 81 is preferentially operated, and the pressure sensors 48 and 49 If the controller determines that the excess pressure energy discharged from the downstream actuator 41 is sufficiently high based on the pressure detection signal, the switching valve device 55 connected to the drain port 73 of the downstream control valve 71 The surplus pressure energy can be regenerated to the pump 23 and the driving device 22 through the regenerative motor 44.

Next, FIG. 7 shows a parallel type driving device 22a installed in place of the series type driving device 22 shown in FIG. 1 and FIG.

[0104] In Fig. 7, the pump 23 and the regenerative motor 44 have swash plates 26 and 45 for variable capacity, respectively, and are directly connected in the same way as in the series system. A gear box 91 is interposed between the engine 21 and the pump 23, and the motor generator 92 functioning as an electric motor and a generator is connected to the pump 23 in parallel with the motor 21 through the gear box 91. A capacitor 94 is connected to the output side of the motor generator 92 via a converter 93.

[0105] The controller (not shown) controls the regulators 95 and 96 for tilting the swash plates 26 and 45 of the pump 23 and the regenerative motor 44 by means of the solenoid proportional valves 97 and 98, and the command actuator is instructed. The capacities of the pump 23 and the regenerative motor 44 are controlled so that the speed can be obtained.

That is, in this parallel type drive device 22a, the rotational shaft of the regenerative motor 44 is mechanically connected to the engine 21 via the pump shaft and the gear box shaft, and the rotational speed of these shafts is determined by the engine 21. Therefore, in order to control the speed of the actuator 41, the tilt angle of the swash plate 45 of the regenerative motor 44 is controlled. In other words, the swash plate 45 is controlled to a low position at low speeds to flow a low flow rate, and the swash plate 45 is controlled to a high position at high speeds to flow a high flow rate. Similarly for the pump 23, the tilt angle of the swash plate 26 is controlled to adjust the flow rate.

[0107] In the case of this parallel type, when the regenerative motor 44 enters the regenerative state, the regenerative motor 44 and the engine 21 are mechanically connected via the gear box 91 or the like. For example, if the stick cylinder 17c (Fig. 8) is powered at the same time and the required power is more than the regenerative power, it will be consumed by this stick system. On the other hand, if the system is powered at the same time or if the required power is smaller than the regenerative power! /, It is connected to the gearbox 91! By causing the motor generator 92 to generate electricity, surplus regenerative power is converted into electric energy and the battery 94 is charged.

In this way, in the parallel drive unit 22a in which the engine 21 and the motor generator 92 are connected in parallel to the pump 23 via the gear box 91, the regenerative motor 44 and the swash plate of the pump 23 are used. By controlling the tilt angles of 45 and 26, these capacities can be controlled to obtain the commanded actuator speed.

Industrial applicability

[0109] The present invention can also be used for work machines other than hydraulic excavators.

Claims

The scope of the claims

[1] a driving device for driving the pump;

The control valve device that controls the fluid pumped from the tank by the pump and supplies it to the actuator, and discharges the fluid returned to the tank into the tank, and the excess pressure of the fluid to be returned to the tank A regenerative motor that recovers energy and regenerates the drive unit;

A pressure detection device for detecting the fluid return side pressure and the fluid containing side pressure of the actuator;

A switching valve device for communicating the fluid return side of the actuator with either the regenerative motor or the tank;

When the fluid return side pressure of the actuator detected by the pressure detector is higher than the fluid entry side pressure and higher than the set value, the fluid return side of the actuator is connected to the regenerative motor, and the fluid return side pressure is the fluid entry side pressure. When the pressure is lower, or when the pressure is lower than the preset value, the controller switches the switching valve device so that the fluid return side of the actuator communicates with the tank.

A fluid pressure drive circuit comprising:

[2] The drive is

A generator connected to the engine;

A motor generator that is electrically connected to the generator and mechanically connected to the pump and functions as a motor and a generator;

A power generator connected to a generator and a motor generator through a converter, and the pump and the regenerative motor each have a variable capacity swash plate,

The controller controls the rotational speed of the regenerative motor and pump by controlling the opening of the switching valve device and the rotational speed of the motor generator so that the commanded actuator speed can be obtained, and the inclination of these swash plates. It controls the turning angle

The fluid pressure drive circuit according to claim 1, wherein:

[3] The pump and regenerative motor each have a swash plate for variable capacity,

The drive device A gearbox interposed between the engine and the pump;

A motor generator connected to the pump in parallel with the engine via a gearbox and functioning as a motor and generator;

A capacitor connected to the motor generator via a converter,

The controller controls the capacity of the regenerative motor and pump so that the commanded actuator speed is obtained by controlling the regenerative motor and swash plate of the pump.

The fluid pressure drive circuit according to claim 1, wherein:

[4] The control valve device includes a plurality of control valves having a spool structure for controlling the plurality of actuators.

The plurality of control valves each have a center bypass passage tandemly connected between the pump and the tank,

The switching valve device was connected to the drain port of the downstream control valve

The fluid pressure drive circuit according to any one of claims 1 to 3, wherein

[5] The switching valve device has an electromagnetic proportional valve

5. The fluid pressure drive circuit according to claim 1, wherein