JPH0228500A - Hydraulic device for battery type industrial vehicle - Google Patents

Abstract

PURPOSE:To prevent the reduction of the working efficiency by installing a hydraulic mechanism for electric power regeneration which can carries out the lowering operation and tilt operation of a fork, onto the hydraulic device for a battery fork. CONSTITUTION:The titled hydraulic device is equipped with a lift cylinder 8, tilt cylinder 15, pressurized oil feeding passage 13 for lift, control valve 7, control valve 12, and a branched stream connecting point 21. Further, an electric motor 3 is installed, and is driven by a battery 1 and drives a hydraulic pump 4 in the normal direction, and when a fork is lowered by a load over a prescribed value, the electric motor 3 is driven by the hydraulic pump 4 which is reversely driven by the pressurized oil which returns through a pressurized oil return passage 14 by the lift cylinder 8, and the electric power regeneration of the battery 1 is carried out. Further, when a lift lever 10 and a tilt lever 11 are simultaneously operated, a portion of the pressurized oil which is returned into a pump 4 through a pressurized oil feedback passage 14 from the cylinder 8 is sent under pressure into the cylinder 15 through the branched stream connection point 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a hydraulic mechanism for power regeneration in a battery-powered industrial vehicle.

[Prior Art] In a battery-powered industrial vehicle, such as a battery forklift, an oil pump is driven to rotate in the normal direction by the forward rotation of the electric motor, and the pressurized oil discharged from the oil pump is supplied to the lift cylinder and the tilt cylinder to raise the fork. and tilting is performed. In some forklifts, when the fork is lowered, the pressure oil discharged from the lift cylinder is returned to the oil pump, and the pump is reversed to drive the electric motor in reverse, and the electric motor is used as a generator, thereby draining the battery. There is one that allows you to charge the battery.

An example of a battery forklift truck having a hydraulic circuit equipped with the power regeneration function is disclosed in Japanese Patent Publication No. 6215478. As shown in FIG. 4, the hydraulic circuit of this forklift includes a main circuit 43 extending from an oil pump 42 driven by an electric motor 41, and a tilt control valve 44.
A tilt cylinder 45 and a lift cylinder 47 are connected through a lift control valve 46 and a lift cylinder 47, respectively.

The lift control valve 46 and the lift cylinder 47
A pressure switch 49 is disposed in the lift circuit 48 that connects the lift circuit 48 with a pressure switch 49 that detects pressure and turns off the pressure, and a limit switch 5 that is activated in response to the operation of the lift lever 50.
1 is provided near the base end of the lever 50. Then, the pressure in the pipe of the lift circuit 48 falls below a predetermined value,
And only when the lift lever 50 is operated to lower the fork, that is, when there are signals from both switches 49 and 51, the bypass circuit 5 branched from the main circuit 43 is activated.
The second electromagnetic switching valve 53 is excited and opened.

When the lift lever 50 is operated to raise the fork, the control valve 46 is switched to the raising side, and the lift circuit 48
The lift cylinder 47 is extended by the pressure oil sent through the fork, and the fork is raised.

Then, in order to lower the fork, the lift control valve 46 is activated as shown in FIG. 5 by operating the lift lever 50.
When switched to the lowering side, pressure oil in the lift cylinder 47 flows from the lift circuit 48 through the control valve 46 into the main circuit 43.

When the load of the descending fork is sufficient, that is, the pressure oil is discharged from inside the lift cylinder 47.

When the oil pressure exceeds a predetermined amount, the pressure switch 49 is also not activated. Therefore, the switching valve 53 only receives the signal from the limit switch 51, and the switching valve 53 is kept closed. Therefore, the pressure oil discharged from the lift cylinder 47 passes through the pump 42 to the tank 54.
The oil pump 4 is returned to
2 functions as a hydraulic motor. For this reason, the electric motor 4
1 can act as a generator and charge the battery.

When the fork is lowered with a light load such as its own weight, the switching valve 5 is activated by signals from both switches 49 and 51.
3 is released. As a result, the return oil from the lift cylinder 47 avoids the pump 42, which has a large passage resistance, passes through the bypass circuit 52, and flows into the tank 54. This prevents the lowering speed of the fork from decreasing, and also reduces the charging effect. Power regeneration is avoided.

Further, when the tilt lever 55 is operated while the lift cylinder 47 is being lowered, the main circuit 43 is shut off by the tilt control valve 44, as shown in FIG. 6, and the return oil from the lift cylinder 47 to the pump 42 is passage is cut off. Therefore, the pipe pressure in the lift circuit 48 increases, the pressure switch 49 is switched, and the bypass circuit 52 is closed by the switching valve 53. Furthermore, the tilt lever 5
5, the operation is detected by the limit switch 56. Then, the battery energizes the electric motor 41 in response to a signal from the limit switch 56, and as the electric motor 41 rotates in the normal direction, the pump 42 is driven in the normal rotation.

[Problems to be Solved by the Invention] Therefore, when a tilt operation is performed when the fork is lowered, the lift cylinder 47 is cut off from the pump 42 to stop the lowering of the fork, and then the tilt cylinder 45, which is communicated with the pump 42, is The tilting movement of the fork is performed by pressure oil that is pumped into the fork.

Therefore, the lowering operation and the tilting operation of the fork cannot be performed at the same time, and the lowering operation is stopped and only the tilting operation is performed, resulting in a decrease in work efficiency.

This invention was made to solve the above-mentioned problems, and its purpose is to provide power regeneration in a battery-powered industrial vehicle that can perform both the lowering operation and the tilting operation of the fork to ensure high work efficiency. The objective is to provide a type hydraulic mechanism.

[Means for Solving the Problem] In order to achieve the above-mentioned object, the present invention provides a lift cylinder that is operated to raise and lower a cargo handling member by operating a lift operating means, and a lift cylinder that is operated to raise and lower a cargo handling member by operating a tilt operating means. a tilt cylinder that is operated to tilt the cylinder; a hydraulic pump that rotates in both forward and reverse directions and discharges pressurized oil to at least one of the two cylinders during forward rotation and functions as a hydraulic motor during reverse rotation; and the lift cylinder. A lift pressure oil supply path is switchably interposed between the lift cylinder and the hydraulic pump, through which the pressure oil discharged by the hydraulic pump rotates in the normal direction when the cargo handling member is raised, and the lift cylinder returns from the lift cylinder when the cargo handling member is lowered. a lift switching means that connects and disconnects the lift cylinder to a pressure oil return path through which the pressure oil passes through by operating the lift operation means, and is switchably interposed between the tilt cylinder and the hydraulic pump,
a tilt switching means that connects and disconnects the tilt cylinder from the tilt pressure oil supply path extending from the hydraulic pump by operating the tilt operating means; an electric motor that is driven by a hydraulic pump that regenerates battery power by being reversed by pressure oil returned from a lift cylinder via a pressure oil return path when the cargo handling member is lowered under a load of a predetermined value or more; The return path is communicated with the tilt supply path, and when the hydraulic pump is reversed by the pressure oil flowing in the pressure oil return path, the pressure oil that receives pressure from the lift cylinder and resistance from the hydraulic pump is fed to the tilt cylinder. The gist is that a pressure oil distribution means is provided.

[Function] This invention employs the solution described above, so that when the lift operation means and the tilt operation means are simultaneously operated to lower and tilt the cargo handling member with a load of a predetermined value or more, the lift A portion of the pressure oil returning from the cylinder to the hydraulic pump through the lift switching means and the pressure oil return path is forced into the tilt cylinder via the pressure oil distribution means due to the pressure from the lift cylinder and the resistance from the hydraulic pump. Ru.

[Embodiment 1] An embodiment in which the present invention is embodied in a hydraulic circuit for a Panteri forklift will be described in detail below with reference to FIGS. 1 to 3.

In FIG. 1, a controller 2 is connected to a battery 1, and an electric motor 3 is driven by the controller 2.

A hydraulic pump 4 is mechanically connected to the electric motor 3, and the hydraulic pump 4 is rotated in the forward direction by the electric motor 3, and the pressure oil stored in the oil tank 5 on the drain side is transferred to the lift lever 10.
, and is adapted to be force-fed to the main circuit 6 side in accordance with the operation of the tilt lever 11. Note that when the fork of the vehicle (not shown) is lowered, the hydraulic pump 4 is rotated in the opposite direction by pressure oil flowing from the main pipe 6 side, that is, return oil, and functions as a motor, causing the electric motor 3 to reverse and rotate. generates power and charges the battery 1.

A drain passage 6a is connected to the main pipe 6, and a lift control valve 7 is disposed in the drain passage 6a, and the lift control valve 7 is connected to a piston chamber 9 of a lift cylinder 8. . This lift control valve 7 is switched by a lift lever 10, and when the lift lever 10 is switched to three positions: up, neutral, and down, the lift control valve 7 is operated to control the lift accordingly. 'lll valve 7 is A,
It is switched to three positions B and C, and controls the direction of flow of pressure oil in the pipe line between the hydraulic pump 4 and the lift cylinder 8. As shown in FIG. 2, when the lift control valve 7 is in position A, the pressure oil that has passed through the lift supply path 13 from the main pipe 6 flows into the lift cylinder 8 via the lift control valve 7. , the fork is raised.

Further, as shown in FIG. 3, when the lift control valve 7 is in the C position, the pressure oil return path 1
The return oil that has passed through the pump 4 flows into the pump 4, and the fork is lowered. Furthermore, as shown in FIG. 1, when the lift control valve 7 is at the 1 and 8 positions, the position of the rod is fixed and the fork is held so as not to move up and down.

Further, the pressure oil return path 14 is connected to the main pipe line 6 via a branch connection point 23 as a pressure oil distribution means, and is further connected to the tilt supply line 18 by this main pipe line 6.

In FIG. 1, a tilt control valve 12 is disposed in the drain passage 6a on the downstream side of the lift control valve 7, and this control valve 12 is connected to the front chamber 16 of the tilt cylinder 15.
and is connected to the rear chamber 17. When the tilt cylinder 15 is operated by the tilt lever 11 and the tilt lever 11 is switched to three positions: backward, neutral, and forward, the tilt control valve 12 is set to A, B in response.
, C can be selected.

As shown in FIG. 2, when the tilt control valve 12 is in the A position, pressure oil from the pump 4 enters the front chamber 16 of the tilt cylinder 15 via the tilt supply path 18 and the tilt control valve 12. At the same time, the rear chamber 17 is communicated with the drain passage 19 by the tilt control valve 12, and the fork is tilted rearward. Further, as shown in FIG. 3, when the tilt control valve 12 is in the C position, pressure oil from the tilt supply path 18 is supplied to the rear chamber 17 of the tilt cylinder 15 via the tilt control valve 12. Along with
The front chamber 16 is connected to the drain path 6a by the tilt control valve 12.
The fork is tilted forward. Further, as shown in FIG. 1, when the tilt control valve 12 is at the 8th position, the front and rear chambers 16 and 17 of the tilt cylinder 15 are respectively cut off from the tilt supply path 18 and the drain path 6a, and the fork The inclination angle of is maintained as it is.

When the lift lever 10 is operated to the upward or downward side, this is detected by the limit switch LSI, and a signal based on this detection operation is output from the limit switch LSI to the controller 2.

Further, the operation amount of the lift lever 10 is detected by a lift lever operation amount sensor 20 consisting of a potentiometer, and a signal based on this detected value is output to the controller 2. Then, when the lift lever 10 is operated to the upward side, the controller 2 maintains the electric motor 3 in the normal rotation power running mode according to the signal from the limit switch LSI, and furthermore, the controller 2 maintains the rotation speed based on the signal from the sensor 20. The electric motor 3 is driven to rotate the pump 4 in the normal direction, and the pump 4 supplies pressure oil in an amount based on the rotational speed of the electric motor 3 to the position A as shown in FIG. 2 via the main pipe 6 and the supply path 13. It is discharged to a certain lift control valve 7.

Further, when the lift lever 10 is operated to the lowered position, the controller 2 converts the electric motor 3 to the power regeneration mode according to a signal from the limit switch LSI. At the same time, by lowering the lift lever 10, the lift control valve 7 is held at the C position shown in FIG. 3, and the return oil flowing out from inside the lift cylinder 8 is returned to the pump 4 via the lift control valve 7. .

The oil pressure in the piston chamber 9 of the lift cylinder 8 is detected by a pressure sensor 21, and when this detected value falls below a preset light load reference value, a signal is output from the pressure sensor 21 to the controller 2. For example, when the lift lever 10 is lowered with the fork empty and a signal from the pressure sensor 21 is output to the controller 2,
The controller 2 invalidates the signal from the lift lever operation amount sensor 20 instructing conversion to the power regeneration mode, and sets the mode of the electric motor 3 to reverse power running mode, thereby reversing the mode. Therefore, when the fork is lowered under a light load, the pump 4 is supplied from the lift cylinder 8 via the lift control valve 7.
Return oil having a low hydraulic pressure flowing into the pump is quickly discharged into an oil tank 5 by a pump 4 which is reversed by an electric motor 3.

Therefore, despite the light load, the contraction of the lift cylinder 8, that is, the lowering of the fork does not occur slowly.

Furthermore, although the pump 4 is reversed, the electric motor 3 is forcibly maintained in the power mode, so that wasteful power regeneration with low charging effect due to return oil of low oil pressure can be avoided.

Note that, at this time, no pressure oil is discharged from the pump 4, and the forward and backward tilting operations of the tilt lever 11 are forcibly stopped.

Further, when the tilt lever 11 is operated from the neutral position to the forward or backward tilting position, the limit switch LS
Detected at 2. A signal based on this detection operation is output from the limit switch LS2 to the controller 2, and the controller 2 maintains the motor 3 in the running mode in accordance with this signal.

In addition, when the pressure sensor 21 is not activated while the lift cylinder 8 is contracting due to the lowering operation of the lift lever 10, that is, when the fork is lowered under a load exceeding a predetermined value, the fork is tilted to perform a tilt operation. Lever 11
When the motor 3 is tilted forward or backward, the limit switch is activated and the controller 2 maintains the electric motor 3 in the power regeneration mode based on a signal from Sl. Therefore, in order to make the pump 4 function as a generator, the return oil is reversed while receiving strong resistance from the vanes inside the pump 4. Therefore, the pressure within the pipeline up to the main pipeline increases. Then, a portion of the pressure oil from the lift cylinder 8 travels from the return path 14 through the branch connection point 23 in the main pipe 6 in the opposite direction to the pump 4, and flows into the tilt supply path 18. Then, the return oil flows from the tilt supply path 18 into the tilt cylinder 15 via the tilt control valve 12. Therefore, the lowering operation and the tilting operation of the fork are performed simultaneously, and furthermore, the battery 1 is charged while performing both of these operations.

In the embodiment described above, when the lift lever 10 is lowered, the fork is lowered and the battery 1 is charged, and when the fork is lowered under a light load, charging of the battery is stopped. By forcibly rotating the pump 4 in the opposite direction, the low hydraulic pressure of the return oil is compensated for, and a rapid downward movement is promoted.

In addition, when the tilt lever 11 is tilted forward or backward while the fork is lowering due to a load exceeding a predetermined value, the fork lowers and tilts at the same time while maintaining the charge of the battery 1, resulting in high work efficiency. can be guaranteed.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, a shovel loader, etc. can be used instead of the hatch lift truck, etc.
As long as it does not deviate from the spirit of this invention, it is possible to adopt a battery-powered industrial vehicle equipped with a hydraulic loading mechanism, or use various electric motors such as DC shunt motors and induction motors as electric motors. It is possible to make changes to the above.

[Effects] As described in detail above, the regeneration hydraulic circuit of the present invention exhibits the excellent effect of ensuring high work efficiency by performing both the lowering and tilting operations of the fork.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing the hydraulic and electrical configuration of this invention, Figure 2 is a circuit diagram showing the hydraulic and electrical configuration when the fork is raised and tilted backward, and Figure 3 is when the fork is lowered. FIG. 4 is a hydraulic circuit diagram in the conventional example, and FIG. Similarly, FIG. 6 is a hydraulic circuit diagram showing the valve switching state when the fork of the conventional example is lowered and tilted forward.

Claims (1)

[Scope of Claims] 1. A lift cylinder that is operated to raise and lower a cargo handling member by operating a lift operating means, and a tilt cylinder that is operated to tilt a cargo handling member by operating a tilt operating means, in the forward and reverse directions. a hydraulic pump that rotates in both directions and discharges pressure oil to at least one of the two cylinders during forward rotation, and functions as a hydraulic motor during reverse rotation, and is switchably interposed between the lift cylinder and the hydraulic pump; For the lift pressure oil supply path through which the pressure oil discharged by the hydraulic pump that rotates normally when the cargo handling member is raised, and the pressure oil return path through which the pressure oil returned from the lift cylinder when the cargo handling member is lowered. a lift switching means that connects and disconnects the lift cylinder by operating the lift operating means; and a tilt pressure oil supply path that is switchably interposed between the tilt cylinder and the hydraulic pump and extends from the hydraulic pump. a tilt switching means that connects and disconnects the tilt cylinder by operating the tilt operation means; and a tilt switching means that is driven by a battery to rotate the hydraulic pump in the normal direction and when the cargo handling member is lowered with a load of a predetermined value or more. The motor includes an electric motor that is driven by a hydraulic pump that is reversed by pressure oil returned from the lift cylinder via a pressure oil return path to regenerate battery power, and the pressure oil return path is communicated with a tilt supply path. , and a pressure oil distribution means for force-feeding the pressure oil that receives pressure from the lift cylinder and resistance from the hydraulic pump to the tilt cylinder when the hydraulic pump is reversed by the pressure oil flowing in the pressure oil return path. Hydraulic systems in battery-powered industrial vehicles.