JPH0744806Y2 - Hybrid hydraulic unit - Google Patents

Description

[Detailed Description of Device] a. The present invention relates to a hydraulic unit that supplies hydraulic oil to an actuator such as a hydraulic cylinder, and further a hybrid hydraulic unit having two types of pumps, an engine driven pump and an electric motor driven pump. Concerning the control of.

(Prior Art) An engine-driven hydraulic pump (engine-driven pump) is used for a hydraulic unit that supplies hydraulic oil to an actuator that operates by supplying hydraulic oil, such as a hydraulic cylinder or hydraulic motor.
And a hydraulic pump driven by an electric motor (electric motor driven pump) connected to a battery. There is also a hybrid hydraulic unit that includes an engine driven pump driven by an engine and an electric motor driven pump, and that is also configured to charge a battery for driving the electric motor by the engine.

In such a hybrid hydraulic unit, the electric motor drive pump is operated only when the flow rate of the hydraulic oil required to operate the actuator at an appropriate operating speed exceeds the discharge amount at the maximum discharge capacity of the engine drive pump. To compensate for the shortage of flow. Therefore, the hydraulic oil is always supplied in accordance with the required flow rate, which enables energy saving or high-speed operation of the actuator.

In order to perform such operation control of the electric motor driven pump, it is necessary to determine whether or not the discharge capacity of the engine driven pump is maximum. As a method therefor, there is a method of detecting the discharge pressure of the engine drive pump and the load pressure when the actuator operates, and performing the following control based on these pressures and their differential pressures.

If the load pressure is less than or equal to the predetermined pressure, the electric motor drive pump is not operated because the actuator is not operating, and if the load pressure exceeds the predetermined load pressure, the difference between the discharge pressure and the load pressure is Is less than or equal to a predetermined differential pressure, the discharge amount of the engine drive pump is determined to be sufficient for the required flow rate of the actuator, and the electric motor drive pump is stopped. On the other hand, when the load pressure exceeds the predetermined load pressure and the difference between the discharge pressure and the load pressure exceeds the predetermined differential pressure, the discharge amount of the engine-driven pump is the maximum, and the discharge amount is the actuation of the actuator. Operate the electric motor drive pump because it is insufficient for the required flow rate.

(Problems to be solved by the invention) However, in such a control method, a plurality of pressure detectors are required for discharge pressure detection and load pressure detection, and a differential pressure between these pressures is calculated, Since the control microcomputer etc. that perform the above control based on the differential pressure are expensive,
There is a problem that the cost of the unit becomes high. Further, such a hydraulic unit is often mounted on a work vehicle, but in order to make it suitable for mounting on a vehicle, the engine driving pump and the engine that drives the generator should be made as small and lightweight as possible to make the unit as a whole. Need to be compact.

In view of the above problems, in the present invention, the operation control of the electric motor drive pump or the like is performed based on the operation / non-operation of the actuator and the level of the operating oil pressure with respect to a predetermined pressure.
Moreover, it is an object of the present invention to provide a hybrid hydraulic unit capable of downsizing the entire unit.

B. Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, in the present invention, an operation detector that detects whether or not an operation control means that controls the supply of hydraulic oil to an actuator is operated. , A pressure detector for detecting whether or not the hydraulic pressure of the hydraulic oil supplied to the actuator is equal to or higher than a predetermined pressure, and the electric motor is turned off when the pressure detector detects that the hydraulic pressure is equal to or higher than the predetermined pressure. And a controller that turns on the electric motor when it is detected that the hydraulic pressure is less than a predetermined pressure, and turns on the generator only when the operation detector does not detect the operation of the operation control means. Form a hybrid hydraulic unit.

(Operation) When such a hydraulic unit is used, for example, when the operator switches the operation control means to the operation side of the actuator by operating the lever or the like, the pressure detector detects that the operating oil pressure is lower than the predetermined pressure. If so, it is assumed that the actuator requires a large amount of hydraulic oil at low pressure, and the controller supplies a large amount of hydraulic oil by the engine drive pump and the electric motor drive pump. Also,
When the pressure detector detects that the working oil pressure is higher than the predetermined pressure, it is assumed that the actuator requires high pressure and a small amount of working oil, and the controller supplies a small amount of working oil only by the engine driven pump. I do.

Therefore, the pressure detector may be one that detects whether the operating oil pressure is equal to or higher than a predetermined pressure and sends an ON / OFF signal. In addition, the controller may control the operation of the electric motor drive pump based on the on / off signal from the operation detector and the on / off signal from the pressure detector. Then, it is not necessary to have a high-level one that controls the operation of the electric motor drive pump or the like based on the pressure difference. Furthermore, since it was decided to drive the generator by the engine only when the OFF signal (signal indicating the stop of the actuator) from the operation detector was input, when the ON signal (signal indicating the operation of the actuator) was input. Almost all of the engine power can be used to drive the pump. For this reason,
The engine can be made smaller and lighter.

(Embodiment) Hereinafter, a preferred embodiment of the hybrid hydraulic unit according to the present invention will be described with reference to the drawings.

FIG. 1 shows an aerial work vehicle using this hydraulic unit.

At four locations on the front, rear, left and right of the body 2 of the aerial work vehicle 1, the body 2
Is mounted on the road surface for stable support (in the figure, the jacks 3 and 4 mounted on the left side of the vehicle body 2 are shown). The lower ends of the jacks 3 and 4 are grounded by extending the jack cylinders 5 and 6 mounted therein. The two jacks attached to the right side of the vehicle body 2 have the same configuration as the jacks 3 and 4.

A swivel base 7 is attached to the rear portion of the vehicle body 2. The swivel base 7 can be swung freely by the rotation of a swivel motor 8. A base end of a boom 9 is pivotally attached to the upper part of the swivel base 7. The boom 9 is composed of a base end side member 9a and a tip end side member 9b, and can be lifted and lowered by expanding and contracting the hoisting cylinder 10. Further, the distal end side member 9b can freely expand and contract with respect to the proximal end side member 9a by the expansion and contraction of the expandable cylinder 11 installed in the proximal end side member 9a. Further, the bucket 12 is attached to the tip of the tip side member 9b. The worker boards this bucket 12 and works at a high place.

Each of the actuators (5, 8, 10, 11, 13,
15 and 16) are all operated by the supply of hydraulic oil, and the device for supplying the hydraulic oil is the hydraulic unit 20 shown in FIG.

First, the configuration of the hydraulic unit 20 will be described.

The hydraulic unit 20 includes an engine drive pump 21 driven by an engine E, an electric motor drive pump 22 mounted in parallel with the pump 21 and driven by an electric motor M, and each actuator (5, 8, 10, 11). It is composed of operation valves (operation control means) (5a, 8a, 10a, 11a) which are attached to each of the control valves (operation control means). From the discharge ports of both pumps 21 and 22, each actuator (5, 8, 1
A pressure switch (pressure detector) 24 is mounted on the main oil passage 23 connected to the (0, 11). Pressure switch 24
Turns on when the operating oil pressure is equal to or higher than a predetermined pressure. Here, the predetermined pressure is, for example, a pressure slightly lower than the set pressure of a relief valve (not shown) provided for circuit protection. The pressure switch 24 is connected to the controller C via a pressure signal line. In addition, the main oil passage 23
An unload valve (solenoid valve) 26 is mounted on a drain oil passage 25 which branches off from and is connected to the tank T. The unload valve 26 has a closed position for closing the drain oil passage 25 and an open position for opening the drain oil passage 25, and is in the closed position when the solenoid 26a is excited, and the solenoid 26a is not excited. When in the open position. The solenoid 26a
Are connected from the controller C via a switching command line. Further, on the power supply line 27 that connects the electric motor M and the battery B that drives the electric motor M, the motor operation switch MS
Is attached. The switch MS is connected to the controller C via on / off line. Further, a generator B for charging the battery B that drives the electric motor M is driven by the engine E, and the generator G is connected to the controller C via an operation command line.

The engine drive pump 21 is a pressure compensation type variable displacement hydraulic pump whose discharge amount decreases as the working oil pressure increases. Further, the operation valve 5a controls all the operations of the four jack cylinders (5, 6 and the like) (second one).
Only the jack cylinder 5 is shown in the figure).

The operation valves (5a, 8a, 10a, 11a) have valve positions such that the jack cylinder 5 is extended / shortened, the swing motor 8 is rotated, and the undulating cylinder 10 is extended / shortened. And telescopic cylinder
Operating position detection switches (operation detectors) (5b, 8b, 10b, 11b) for detecting that the actuator 11 is in a position for extending / shortening (hereinafter referred to as an operating position of each actuator) are attached. The operating position detection switch (5b,
8b, 10b, 11b) are connected to the controller C via separate signal lines.

Next, the operation of the hydraulic unit 20 will be described.

When a worker operates a lever or the like to operate any of the actuators (5, 8, 10, 11), the operation position detection switch (5b, 8b, 10b or 11b) of the selected actuator is operated. An operating position detection signal is sent to the controller C. At this time, the controller C first energizes the solenoid 26a to position the unload valve 26 at the closed position, and supplies hydraulic oil to the actuator. Next, the operation of the selected actuator is larger than the maximum discharge amount of the engine-driven pump 21, such as the expansion and contraction operation of the jack cylinder (5, 6 and the like) or the expansion operation of the expansion and contraction cylinder 11, and the hydraulic oil flow rate (large flow rate). ) Is required, the working hydraulic pressure does not reach the predetermined pressure and the pressure switch 24 is turned off. At this time, the controller C turns on the motor operation switch MS to operate the electric motor drive pump 22, and stops the generator G.

On the other hand, the operation of the actuator is the rotation operation of the swing motor 8, the expansion / contraction operation of the hoisting cylinder 10, or the expansion / contraction cylinder.
When only the hydraulic oil flow rate of the maximum discharge amount of the engine drive pump 21 or less is required as in the shortening operation of 11, the hydraulic pressure becomes higher than a predetermined pressure and the pressure switch 24 is turned on. At this time, the controller C turns off the motor operation switch MS to stop the electric motor drive pump 22 and also stops the operation of the generator G.

In addition, neither actuator is operated (non-operation)
In this case, the operating position detection signal is not sent from any of the operating position detection switches, and the controller C is
26 is placed in the open position and hydraulic oil is drained to the tank T. At this time, the hydraulic pressure does not rise, so the pressure switch 24
Turns off. Then, the controller C stops the electric motor drive pump 22 and operates the generator G to charge the battery B. In this way, by operating the generator G only when the actuator is not operating, when the actuator is operating, all of the engine power can be used for driving the pump, and accordingly, the engine can be made smaller, that is, Noise reduction is possible.

FIG. 3 is a table summarizing the operation of the hydraulic unit described above.

C. Effects of the Invention As described above, in this hydraulic unit, the operation of the electric motor drive pump and the like is controlled based on the on / off signal from the operation detector and the on / off signal from the pressure detector, and the actuator is required. Since it supplies the amount of hydraulic oil, it is a high-performance system that controls the operation of electric motor driven pumps by calculating multiple pressure detectors that detect the discharge pressure and load pressure of engine driven pumps and the pressure differences between them, as in the past. Since no controller is required, the cost of the unit can be reduced. Furthermore, since it was decided to drive the generator by the engine only when an OFF signal (a signal indicating the stop of the actuator) was input from the operation detector, when an ON signal (a signal indicating the operation of the actuator) was input. Almost all of the engine power can be used to drive the pump. Therefore, the engine can be reduced in size and weight.

[Brief description of drawings]

FIG. 1 is a perspective view showing an aerial work vehicle using a hybrid hydraulic unit according to the present invention, FIG. 2 is a schematic view showing the configuration of the hydraulic unit, and FIG. 3 is a diagram showing the operation of the hydraulic unit. It is the table shown. 5, 6 ... Jack cylinder 8 ... Slewing motor, 10 ... Elevating cylinder 11 ... Telescopic cylinder 21 ... Engine drive pump 22 ... Electric motor drive pump 24 ... Pressure switch, 26 ... Unload valve G ... Generator

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Claims (1)

[Scope of utility model registration request] 1. A hybrid hydraulic unit for supplying hydraulic oil to an actuator, the engine driving pump driven by an engine, a motor driving pump driven by an electric motor, and the hydraulic oil discharged from these pumps. An operation detector for detecting whether or not an operation control means for performing supply control to the actuator has been operated, a pressure detector for detecting whether or not the hydraulic pressure of the hydraulic oil discharged from the both pumps is equal to or higher than a predetermined pressure, A generator that is driven by an engine and charges a battery that drives the electric motor; and when the pressure detector detects that the hydraulic pressure is equal to or higher than the predetermined pressure, the electric motor is turned off, and the hydraulic pressure is changed. Is detected to be below the predetermined pressure, the electric motor is turned on, and the operation detector detects the Hybrid hydraulic units that control means is not operated is characterized in that it consists of a controller to turn on the generator only when it is detected.