JP5963588B2 - Lifting mechanism - Google Patents

Description

The present invention relates to elevator structure having a lift cylinder.

As this type of device, for example, the device described in Patent Document 1 has been conventionally known.
In this conventional apparatus, an electric motor whose inverter is controlled by a hydraulic pump is used as a drive source, and a switching valve having a check valve is connected to a flow path connecting the hydraulic pump and a lift cylinder.

The check valve provided in the switching valve is configured to allow only the flow from the hydraulic pump to the lift cylinder. Therefore, when this switching valve is switched to the check valve position, the lift cylinder stops and holds the load.
In the apparatus as described above, the operation speed of the lift cylinder is controlled by controlling the rotation speed of the electric motor.

  When the lift cylinder is lowered, the lowering speed is controlled by controlling the rotation speed of the electric motor. Furthermore, when stopping the lift cylinder when it is lowered, the lowering speed is slowed in advance, and the switching valve is switched to the check valve position when the lowering speed becomes slow to some extent.

JP-A-8-26697

In the conventional apparatus as described above, the switching valve is switched to the check valve position after the lift cylinder descending speed has slowed to some extent. For example, when the weight of the object placed on the loading platform is large, Even if the lowering speed of the lift cylinder is slow, there is a problem that a shock occurs when the switching valve is switched.
The purpose of the present invention is to provide a lift structure that shock does not occur even when stopping it when the lift cylinder lowering.

The first invention includes a lift cylinder that raises and lowers a cargo bed, a fluid pressure pump, a flow path that connects the fluid pressure pump and the lift cylinder, a fluid pressure motor that operates with a return fluid from the lift cylinder, and the fluid A regenerative mechanism having an electric motor that functions as a generator by the operation of the pressure motor, an on-off valve mechanism that opens and closes a flow path provided between the fluid pressure pump and the regenerative mechanism and the lift cylinder, and a lift signal of the loading platform operation means for outputting, and a brake mechanism to maintain a state in which the electric motor is stopped, the descending control of the loading platform, when a signal for stopping the lowering of the loading platform from the operation means is outputted, the electric The motor functions as a generator, the brake mechanism is operated after the lift cylinder contraction speed is reduced, and the rotation of the fluid pressure motor stops. Characterized in that closing said opening and closing valve mechanism.

According to a second aspect of the present invention, when a signal for stopping the lowering of the loading platform is output from the operation means during the lowering control of the loading platform, the electric motor functions as a generator, and the contraction speed of the lift cylinder is reduced. characterized in that the lift cylinder is Ru actuates the braking mechanism after stopping.

The third invention is characterized in that the fluid pressure pump and the fluid pressure motor comprise an integral fluid pressure pump / motor .

The fourth invention is characterized in that the electric motor consumes the inertia energy of the lift cylinder as regenerative energy by the operation of the fluid pressure motor and exhibits a deceleration function for the fluid pressure pump .

According to the first invention, by operating the braking mechanism after the contraction rate of the lift cylinder is decelerated, the rotation of the fluid pressure motor has to close the opening and closing valve mechanism After stopping, mitigating stop shock it can.
According to the second invention, when the signal for stopping the lowering of the loading platform is output from the operation means when the loading platform is lowered, the open / close valve mechanism is closed after the regeneration mechanism is stopped. It will be alleviated further.

According to the third invention, since the fluid pressure pump also serves as the fluid pressure motor that operates the regeneration mechanism, the configuration can be simplified.

According to the fourth invention, the fluid energy of the return fluid of the lift cylinder can be recovered, so that the energy can be reused. In addition, the electric motor consumes the inertial energy of the lift cylinder as regenerative energy and also exerts a deceleration function for the fluid pressure pump. Therefore, after the inertial energy is consumed by the regenerative mechanism, the motor stops when the open / close valve mechanism is closed The shock of time can be further reduced.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In the illustrated embodiment, a hydraulic pump P and a lift cylinder LC that are capable of forward and reverse rotation are connected via a flow path 1, and the flow path 1 includes a first opening / closing valve mechanism of the present invention. An electromagnetic switching valve V1 is provided.
The hydraulic pump P constitutes a fluid pressure pump of the present invention.
The first electromagnetic switching valve V1 is a two-port two-position switching valve that can be switched between a closed position (a) that is a normal position and an open position (b) that is a switching position.

A check valve mechanism 2 is provided at the closed position (a) of the first electromagnetic switching valve V1. The check valve mechanism 2 blocks the flow of the flow path 1 and exhibits load holding capability for the lift cylinder LC.
On the other hand, the flow path 3 which connects the flow path 1 is provided in the said open position (b) of the 1st electromagnetic switching valve V1. Therefore, when the first electromagnetic switching valve V1 is in the open position (b), the hydraulic pump P and the lift cylinder LC communicate with each other via the flow passage 3.

The lift cylinder LC is a single-acting cylinder, which connects the head side chamber 5 defined by the piston 4 to the flow path 1, and has a loading platform 7 at the tip of the piston rod 6.
When pressure oil is supplied to the head side chamber 5, the lift cylinder LC extends to raise the loading platform 7. On the other hand, when the pressure oil in the head side chamber 5 is released, the lift cylinder LC contracts due to its own weight and the load of the loading platform 7.

Further, the branch flow paths 8 and 9 are connected to the flow path 1 on the upstream side of the first electromagnetic switching valve V1 with respect to the flow from the hydraulic pump P to the lift cylinder LC. Is connected to a tilt cylinder TC via a second electromagnetic switching valve V2.
The second electromagnetic switching valve V2 is a four-port three-position switching valve. The ports 10, 11 are connected to the branch flow paths 8, 9, and the ports 12, 13 are connected to the tilt cylinder TC.
In the figure, reference numeral 14 is a check valve that allows only the flow from the second electromagnetic switching valve V2 to the hydraulic pump P.

The tilt cylinder TC is for tilting the loading platform 7 so that an object placed on the loading platform 7 does not fall.
Reference numeral 15 denotes an operation check valve, which normally allows only the flow from the second electromagnetic switching valve V2 to the rod side chamber 16 of the tilt cylinder TC. However, the pressure in the head side chamber 17 of the tilt cylinder TC When the pressure is higher than the pressure, the flow from the rod side chamber 16 to the second electromagnetic switching valve V2 is allowed.

The joystick 18 performs the switching operation of the first and second electromagnetic switching valves V1, V2. The joystick 18 constitutes the operating means of the present invention.
In addition, since this invention has the characteristics in control of the lift cylinder LC, the 1st electromagnetic switching valve V1 is demonstrated below.
When the joystick 18 is maintained in the neutral position, the first electromagnetic switching valve V1 maintains the illustrated closed position (a), and when the joystick 18 is tilted in either direction, the first electromagnetic switching valve V1 is in the open position. Switch to (b).

The joystick 18 is also electrically connected to the controller C. The controller C is connected to an electric motor M and a brake mechanism B including an electric brake that keeps the electric motor M stopped. The controller C controls the rotational speed of the electric motor M according to the tilt angle of the joystick 18 and also controls the rotation direction of the electric motor M according to the tilt direction.
In the figure, reference numeral 19 denotes a battery connected to the controller C, and 20 denotes a relief valve.

Next, the operation of the above embodiment will be described. When the lift cylinder LC is extended to raise the loading platform 7, the joystick 18 is tilted in a predetermined direction, that is, the direction in which the lift cylinder LC is extended. When the joystick 18 is tilted in the direction in which the lift cylinder LC is extended in this way, the controller C determines from the direction of the tilt that the signal in the extension direction has been input from the joystick 18.

When a signal in a direction for extending the lift cylinder LC is input from the joystick 18, the controller C rotates the electric motor M forward and the hydraulic pump P forward.
When the joystick 18 is tilted in the extending direction, the raising signal is transmitted to the first electromagnetic switching valve V1, and the first electromagnetic switching valve V1 is switched from the closed position (a) to the open position (b). If the first electromagnetic switching valve V <b> 1 is switched to the open position (b), the flow path 1 flows through the flow path 3.

Accordingly, the pressure oil discharged from the hydraulic pump P is guided to the head side chamber 5 of the lift cylinder LC via the flow path 1 to extend the lift cylinder LC and raise the loading platform 7.
The ascending speed of the loading platform 7 at this time is controlled by the rotation speed of the hydraulic pump P, that is, the rotation speed of the electric motor M. The rotation speed is controlled by the controller C according to the tilt angle of the joystick 18.

When the lift cylinder LC is extended to the target position as described above, the joystick 18 is returned to the neutral position. When the joystick 18 is returned to the neutral position, the controller C stops the electric motor M and stops the hydraulic pump P.
When the joystick 18 is returned to the neutral position, the first electromagnetic switching valve V1 is also returned to the closed position (a), and the communication between the hydraulic pump P and the head side chamber 5 of the lift cylinder LC is shut off.
Therefore, the lift cylinder LC stops and holds its stop position.

  When the lift cylinder LC is contracted and the loading platform 7 is lowered, the joystick 18 is tilted in a direction in which the lift cylinder LC is contracted. When the joystick 18 is tilted in the contraction direction in this way, the first electromagnetic switching valve V1 is switched from the closed position (a) to the open position (b) in response to the signal.

  Further, when the joystick 18 is tilted in the direction in which the lift cylinder LC is contracted, the contraction signal is input to the controller C. When the contraction signal is input from the joystick 18, the controller C reversely rotates the electric motor M and the hydraulic pump P, and also controls the number of rotations according to the tilt angle of the joystick 18.

If the hydraulic pump P rotates in the reverse direction as described above, the return oil from the lift cylinder LC is supplied to the hydraulic pump P and returned from the hydraulic pump P to the tank T.
Therefore, the contraction speed of the lift cylinder LC, that is, the descending speed of the loading platform 7 is controlled by the rotational speed of the hydraulic pump P.

When the lift cylinder LC is stopped in the process of lowering the loading platform 7 as described above, the joystick 18 is returned to the neutral position. However, when the joystick 18 is returned to the neutral position, the first electromagnetic switching valve V1 is not immediately switched. That is, after stopping it shrinkage rate is sufficiently decelerated lift cylinders LC, the first electromagnetic switching valve V1 is in so that automatically turn the closed position is a normal position (a).

  The timing of switching the first electromagnetic switching valve V1 to the closed position (a) is measured in advance by how long the lift cylinder LC stops in the actual machine after the joystick 18 is returned to the neutral position. The time is set in the joystick 18 as the switching timing.

That is, in the above embodiment, when the lift cylinder LC is stopped when the loading platform 7 is lowered, the switching timing of the first electromagnetic switching valve V1 is delayed by a predetermined time. The control method is not limited to time delay.
For example, it is possible to electrically detect whether the brake mechanism B performs a brake operation, and transmit the signal to the joystick 18 to switch the first electromagnetic switching valve V1 to the closed position (a).

The first electromagnetic switching valve V1 is also connected to the controller C. The controller C receives the signal when the joystick 18 returns to the neutral position when the loading platform 7 is lowered, and the brake mechanism B and the first electromagnetic You may make it control both the switching valves V1.
In any case, when the joystick 18 returns to the neutral position as described above, the controller C switches off the electric motor M and makes it rotate freely.
The electric motor M also has a function as a generator, and the generated power is stored in the battery 19.

Therefore, the electric motor M functions as a drive source for the hydraulic pump P, when the hydraulic pump P is rotated by utilizing the inertia energy when the lift cylinder LC is lowered function as the generator.
When this way the electric motor M functions as a generator, the inertial energy of the lift cylinders LC is consumed as a generated energy, shrinkage rate of the lift cylinders LC is decelerated.

When the contraction speed of the lift cylinder LC is reduced and the lift cylinder LC is stopped, the controller C operates the brake mechanism B to stop the rotation of the hydraulic pump P functioning as a hydraulic motor.
When the rotation of the hydraulic pump P stops, the controller C returns the first electromagnetic switching valve V1 from the open position (b) to the closed position (a).
Therefore, almost no shock occurs when the lift cylinder LC is stopped.

In the above embodiment, the hydraulic pump P also functions as a hydraulic motor serving as a driving source for the electric motor M functioning as a generator.
Then, in the above embodiment, the hydraulic pump P which serves as a hydraulic motor, both the electric motor M functions as a generator, that make up the regenerative mechanism for generating electric power through the use of regenerative energy of the lift cylinders LC.
However, the hydraulic motor of the regenerative mechanism, provided separately from the hydraulic pump, the rotational force of the hydraulic motor may be configured to transmit to the electric motor M functioning as the generator.

  The present invention is most suitable for use in a forklift.

P Hydraulic pump LC Lift cylinder 1 Flow path V1 First electromagnetic switching valve 7 Loading platform 18 Joystick C Controller M Electric motor B Brake mechanism

Claims (4)

A lift cylinder that raises and lowers the loading platform;
A fluid pressure pump;
A flow path connecting the fluid pressure pump and the lift cylinder;
A regenerative mechanism having a fluid pressure motor that operates with a return fluid from the lift cylinder and an electric motor that functions as a generator by the operation of the fluid pressure motor ;
An open / close valve mechanism for opening and closing a flow path provided between the fluid pressure pump and the regeneration mechanism and the lift cylinder;
Operation means for outputting a lifting signal of the cargo bed;
A brake mechanism that keeps the electric motor stopped,
When a signal for stopping the descent of the cargo bed is output from the operating means during the descent control of the cargo bed,
An elevating mechanism that causes the electric motor to function as a generator, operates the brake mechanism after the contraction speed of the lift cylinder is decelerated, and closes the open / close valve mechanism when the rotation of the fluid pressure motor stops . When a signal for stopping the descent of the cargo bed is output from the operation means during the descent control of the cargo bed,
The electric motor to function as a generator, lifting mechanism of claim 1, wherein the lifting cylinder contraction speed of the lift cylinder is decelerated Ru actuates the braking mechanism after stopping. The lifting mechanism according to claim 1 or 2, wherein the fluid pressure pump and the fluid pressure motor comprise an integral fluid pressure pump / motor . The elevating mechanism according to any one of claims 1 to 3, wherein the electric motor consumes the inertia energy of the lift cylinder as regenerative energy by the operation of the fluid pressure motor and exhibits a deceleration function for the fluid pressure pump. .

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