JP2978750B2 - Construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction machine such as a hydraulic shovel, a bulldozer, a loader and the like using a battery as a power source.

[0002]

2. Description of the Related Art Construction machines such as hydraulic shovels generally use an engine as a power source. That is, the hydraulic pump is driven by the engine, and the hydraulic pressure generated by the hydraulic pump is controlled by the hydraulic valve to operate the hydraulic cylinder and the like of the working machine.

FIG. 5 shows an example of a conventional hydraulic excavator, in which an engine-related device such as an engine and a radiator is arranged at a rear portion of an operator space 1 and an engine hood 2 is provided.
And hydraulic-related equipment such as a hydraulic tank, a hydraulic pump, and a hydraulic valve are arranged on the side of the operator space 1 and covered with the side cover 3.

In the operator space 1, the seat 4
Various levers such as an operation lever 6 for operating the work machine 5, a traveling lever 7, a swing swing pedal 8, and the like, a pedal, and switches are arranged around the work device 5.

As described above, since the conventional hydraulic excavator uses the engine as a power source, it has environmental problems such as noise and exhaust gas generated from the engine, and is limited to work in a city area, at night, in a tunnel, or the like. Is receiving.

FIG. 6 shows a hydraulic circuit of such a hydraulic shovel, in which the suction side of a hydraulic pump 92 driven by an engine 91 is inserted into a hydraulic tank 93, and a filter 94 and a pressure setting Relief valve 95 and pilot valve 96
The pilot valve 96 is operated by an operator's lever operation or the like, the main control valve 97 is operated by the pilot pressure output from the pilot valve 96, and the hydraulic pump 92 or a separate hydraulic pump passes through the main control valve 97. The direction control and the flow rate control of the hydraulic oil supplied to the actuator 98 are performed.

Thus, the hydraulic pump 92 is driven by the engine 91.
When driving, because refueling is easy,
It is not necessary to stop the rotation of the engine 91 even when the operation lever 6, the traveling lever 7, the turning swing pedal 8 and the like are not operated.

For this reason, when the pilot valve 96 is operated by the operating lever 6 or the like, the pilot valve 96 which is always receiving the supply of the pressure oil from the hydraulic pump 92 constantly driven by the engine 91 immediately outputs the pilot pressure. be able to.

On the other hand, the applicant according to the present invention starts an electric motor by using a large battery mounted on the machine body, instead of the conventional engine having environmental problems such as noise and exhaust gas, and starts the electric motor. A construction machine that drives a hydraulic pump of a hydraulic circuit by a motor has been proposed.

In this type of electro-hydraulic construction machine, it is necessary to minimize the consumption of a battery which requires time for charging from the viewpoint of work efficiency. When the hydraulic actuator is not operated, the electric motor is stopped. Preferably, the electric motor is started by an operation signal for operating the hydraulic actuator.

[0011]

As described above, in the electro-hydraulic construction machine, even if the electric motor is started by the operation signal for operating the hydraulic actuator, the rotation speed of the electric motor stopped when it is not operated is increased. Takes some time and the pilot pressure does not rise immediately.

Therefore, the operation of the main control valve cannot be performed immediately, and the response from the input of the operation signal to the operation of the hydraulic actuator is not good.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to rapidly increase the pilot pressure at the start of an electric motor in a construction machine in which an electric motor drives a hydraulic pump of a hydraulic circuit. It is another object of the present invention to improve the responsiveness from the input of the operation signal to the activation of the hydraulic actuator.

[0014]

According to a first aspect of the present invention, there is provided a construction machine in which a working machine is mounted on a machine body provided with a traveling device, wherein a battery mounted on the machine body is used as a power source. An electric motor activated by an operation signal for operating at least one of the hydraulic actuators of the traveling device and the working machine, a hydraulic pump driven by the electric motor, and a hydraulic pressure discharged from the hydraulic pump according to the operation signal. A pilot valve for converting to a pilot oil pressure, a main control valve that operates by the pilot oil pressure supplied from the pilot valve to control the hydraulic oil supplied from the hydraulic pump to the hydraulic actuator, and between the hydraulic pump and the pilot valve. And an accumulator provided for the pipeline.

[0015] The delay in the rising pressure from the hydraulic pump to the pilot valve due to the gradual increase in the motor rotation speed when the electric motor is started by turning on the operation signal is compensated for by the hydraulic pressure accumulated in the accumulator, thereby ensuring the responsiveness of the main control valve. I do.

According to a second aspect of the present invention, in the construction machine according to the first aspect, a solenoid valve is interposed between the accumulator and the pipeline.

The electromagnetic valve is opened at the same time when the electric motor is started by turning on the operation signal, the hydraulic pressure accumulated in the accumulator is released to the pipeline, and power is continuously supplied to the electric motor for a certain period of time after the operation signal is turned off. By operating the hydraulic pump for a certain period of time, the accumulated pressure in the accumulator is secured and then the solenoid valve is closed.

According to a third aspect of the present invention, in the construction machine according to the first aspect, the pump is located closer to the pump than a portion where the accumulator is connected in a pipeline between the hydraulic pump and the pilot valve. A check valve for preventing backflow of hydraulic oil to the side is interposed.

When the discharge pressure of the hydraulic pump at the time of starting the electric motor is not sufficient, the check valve prevents backflow from the accumulator to the pump side.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to FIGS.

FIGS. 3 and 4 show an electric hydraulic excavator according to the present invention, in which a machine main body (slewing table) 14 is pivotally provided by a swivel bearing 13 on a traveling device 12 on which a crawler belt 11 is mounted.
A blade 16 is attached to a front portion of the traveling device 12 by an arm 15, and a work implement 17 is attached to a front portion of the machine body 14.

As shown in FIG. 3, in the upper part of the machine body 14, one battery box 22 is arranged from above the turning center 21 to one side. This battery box 22
It is a box body provided with an openable and closable lid plate 22a on the upper surface, and houses therein a large number of batteries 22b connected in series and in parallel.

The battery box 22 is mounted on the machine main body 14 by a crane or a forklift.
When the battery b is consumed, the battery box 22 is detachably mounted with a bolt (not shown) so that the battery box 22 can be replaced with a charged battery box.

A battery is provided at the rear of the battery box 22.
DC motor as electric motor operated by 22b
And a hydraulic pump 24 driven by the DC motor 23
And an oil cooler 25 for suppressing an increase in oil temperature in the hydraulic circuit, and these are covered with a hood 26 that can be freely opened and closed.

Further, a hydraulic tank 27 and a hydraulic valve 28 are arranged on the other side of the machine body 14. This hydraulic valve 28
Is supplied from the hydraulic tank 27 to a plurality of hydraulic actuators (hydraulic motors, hydraulic cylinders) of a traveling system, a swing system, and a working machine system (hereinafter, the swing system and the working machine system are called working systems) by the hydraulic pump 24. It is composed of a number of hydraulic valves for controlling the hydraulic oil, respectively, and is operated by a command signal input from outside the machine body 14 as described later.

As shown in FIG. 4, the working machine 17 includes a boom 32 which is vertically turned by a boom hydraulic cylinder 31.
Arm 34 rotated by an arm hydraulic cylinder 33
And a bucket 37 that is rotated by a bucket hydraulic cylinder 35 via a bucket linkage 36.

This work machine 17 is mounted at the front of the machine body 14 so as to be able to swing horizontally. That is, the machine body 14
A swing post 41 formed in a substantially U-shape is rotatably supported in a horizontal direction on a swing frame 41 protruding from the hydraulic cylinder for boom.
The base ends of the boom 31 and the boom 32 are rotatably supported in the vertical direction.

A rod end of a hydraulic cylinder 43 for swing provided in the machine main body 14 is connected to one side surface of the swing post 42 via linkages 44 and 45, and the hydraulic cylinder 43 for swing is extended and contracted. The swing post 42 is rotated left and right. As a result, the work machine 17 swings right and left.

Further, as shown in FIGS. 3 and 4, on one side of the machine body 14 and along one side of the battery box 22, power is supplied from the battery 22b to control various hydraulic actuators. The controller 48 for controlling the hydraulic valve for use is erected.

The controller 48 includes a battery box
The power supplied from the battery 22b in the battery 22 is controlled based on an operation signal input from a remote control device such as a wireless control device or a wired control device (both not shown), and the DC motor 23, the traveling system or A current is supplied to a solenoid of an electromagnetically operated pilot valve for controlling various hydraulic actuators of a working system.

Further, as shown in FIG.
A pilot valve 54 that converts a working oil pressure discharged from the hydraulic pump 24 into a pilot oil pressure according to the operation signal through a filter 52 and a check valve 53 to a discharge pipe line 51 of a hydraulic pump 24 driven by 23. Connect the supply port.

The pilot valve 54 may be a single electromagnetic proportional valve, or a composite valve combining, for example, an electromagnetically operated proportional pressure reducing valve and a direction switching valve. The pilot pressure line 55 passing through the pilot valve 54 is connected to pilot pressure action portions 56a and 56b on both sides of the main control valve 56.

The main control valve 56 has a built-in spool which operates according to the pilot pressure supplied from the pilot valve 54,
The direction and flow rate of hydraulic oil supplied from the hydraulic pump 24 or another hydraulic pump to the traveling or working hydraulic actuator 57 via this spool are controlled.

In such a pilot pressure control circuit, the pipeline 51 between the hydraulic pump 24 and the pilot valve 54
, An accumulator 62 is provided via an electromagnetic valve 61. The accumulator 62 stores the pressure inside the pipe 51 when the pipe 51 is at high pressure by the action of the built-in compressible gas,
Has a function of discharging the stored pressure to the pipeline 51 when the pressure is low.

The solenoid valve 61 interposed between the accumulator 62 and the pipeline 51 switches when the operating current is supplied from the controller 48 to its solenoid 61a, against the return spring 61b, and the solenoid valve 61 switches. The path 51 communicates with the accumulator 62.

The check valve 53 is provided in the pipeline 51 between the hydraulic pump 24 and the pilot valve 54 and on the pump side from a portion 51a where the accumulator 62 is connected to the pipeline 51. To prevent backflow of hydraulic oil from the pump to the pump side.

Next, the operation of the embodiment shown in FIG. 1 will be described.

The operator inputs an operation signal for traveling or work to the controller 48 from the outside of the machine body 14 by a command device of a wireless control device or a wired control device.

When this operation signal is input, the controller 48 starts the DC motor 23 powered by the battery 22b in the battery box 22 and drives the hydraulic pump 24 of a hydraulic source directly connected to the DC motor 23. At the same time, the solenoids of the various pilot valves 54 are energized and the main control valve 56 is controlled by the pilot pressure output from the pilot valves 54.

The main control valve 56 controls the direction and flow rate of the hydraulic oil supplied from the hydraulic pump 24 or another hydraulic pump to the supply port P of the main control valve 56, so that the traveling system or the working system (swing system and It is supplied to the hydraulic actuator 57 of the working machine system) to control the operating direction and speed of the hydraulic actuator 57.

As shown in FIG. 2, even if the DC motor 23 is started by turning on the operation signal, the motor rotation speed does not increase rapidly and the pump discharge pressure does not increase sharply. At the same time, the solenoid 61a of the solenoid valve 61 is excited to open the solenoid valve 61, and the hydraulic pressure accumulated in the accumulator 62 is discharged to the pipeline 51.

Thus, the hydraulic pump caused by the gradual increase of the motor rotation speed when the DC motor is started by turning on the operation signal
The delay in the rising pressure from 24 to the pilot valve 54 is compensated for by the hydraulic pressure accumulated in the accumulator 62, and the pilot pressure is rapidly increased at the same time as the operation signal is turned on, thereby ensuring the responsiveness of the main control valve 56, The responsiveness of the operating pressure supplied from the control valve 56 to the hydraulic actuator 57 such as a working machine is improved.

In FIG. 2, a two-dot chain line shows a characteristic curve when no accumulator is provided, and a solid line shows a characteristic curve when an accumulator is provided.

When the discharge pressure of the hydraulic pump 24 at the time of starting the DC motor is not sufficient, the check valve 53
Prevents backflow from 62 to the pump 24 side.

When the operation signal is turned off, the pilot valve 54 returns to the neutral position and closes the pipe line 51. By operating 24 for a certain period of time and energizing the solenoid valve 61 for a certain period of time,
The pressure oil is supplied from the pipe line 51 to the accumulator 62, and after accumulating the pressure inside the accumulator 62, the power supply to the solenoid valve 61 is stopped and the solenoid valve 61 is closed.

When the battery 22b is exhausted, the battery box 22 is removed from the machine body 14 and replaced with a battery box containing a charged battery.

Finally, the present invention is not limited to hydraulic excavators, but can be applied to other construction machines such as bulldozers and loaders.

[0048]

According to the first aspect of the present invention, since the accumulator is provided in the pipeline between the hydraulic pump and the pilot valve, the motor speed at the time of starting the electric motor by turning on the operation signal is reduced. The delay of the rising pressure from the hydraulic pump to the pilot valve due to the gradual increase is compensated for by the hydraulic pressure accumulated in the accumulator, and the quick response of the main control valve can be ensured.

According to the second aspect of the present invention, since the solenoid valve is interposed between the accumulator and the pipeline, opening and closing the solenoid valve releases the hydraulic pressure from inside the accumulator to the pipeline and causes the accumulator to open. It is possible to reliably control the pressure accumulation in the inside.

According to the third aspect of the present invention, since the check valve is interposed on the pump side from the accumulator connection portion, when the discharge pressure of the hydraulic pump at the time of starting the electric motor is not enough, the check valve is moved from the accumulator to the pump side. Can be prevented by the check valve.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a hydraulic circuit in a construction machine according to the present invention.

FIG. 2 is a characteristic diagram showing an effect of a hydraulic circuit in the construction machine.

FIG. 3 is a plan view of the construction machine.

FIG. 4 is a perspective view of the construction machine.

FIG. 5 is a plan view showing a conventional construction machine.

FIG. 6 is a circuit diagram showing a conventional hydraulic circuit.

[Explanation of symbols]

 12 Traveling device 14 Machine body 17 Work machine 22b Battery 23 DC motor as electric motor 24 Hydraulic pump 51 Pipe line 53 Check valve 54 Pilot valve 56 Main control valve 57 Hydraulic actuator 61 Solenoid valve 62 Accumulator

Claims (3)

(57) [Claims] 1. A construction machine in which a working machine is mounted on a machine body provided with a traveling device, wherein a battery mounted on the machine body is used as a power source to operate at least one hydraulic actuator of the traveling device and the working machine. An electric motor started by an operation signal, a hydraulic pump driven by the electric motor, a pilot valve for converting a working oil pressure discharged from the hydraulic pump into a pilot oil pressure according to the operation signal, and supplied from the pilot valve A main control valve that operates by a pilot hydraulic pressure to control hydraulic oil supplied from a hydraulic pump to a hydraulic actuator; and an accumulator provided for a pipeline between the hydraulic pump and the pilot valve. A construction machine characterized by the above. 2. The construction machine according to claim 1, wherein an electromagnetic valve is interposed between the accumulator and the pipeline. 3. A check valve for preventing backflow of hydraulic oil to the pump side from a portion connected to the accumulator in a pipeline between the hydraulic pump and the pilot valve. The construction machine according to claim 1, wherein: