JPH0727766Y2 - Low-lift type vehicle handling speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a traveling speed control device for a low lift type cargo handling vehicle such as a pallet lift truck suitable for handling palletized cargo.

<Prior art> In this type of conventional lift truck, the traveling speed is switched between three stages depending on the position of the gear shift lever, and in order to maintain the maximum speed of the third speed The push button switch for maintaining the high speed, which is additionally provided, needs to be continuously pressed while operating the angle and holding the position by the thumb. However, this operation requires a fairly unreasonable hand operation, and the driving posture becomes unnatural, so there is a drawback in that the driver is tired if the vehicle runs for a long distance in this state.

<Problems to be solved by the invention> Therefore, when moving a long distance, it is possible to maintain the third speed just by operating the shift lever as in the case of the first and second speeds without continuously pressing the high speed button. Is desired.

<Means for Solving Problems> An object of the present invention is to provide an above-mentioned device. The purpose is to open and close the motor drive circuit for driving the traveling motor at the first speed, the second speed and the third speed from low speed to high speed according to the operation position of the shift lever, and to open and close each contact of the motor drive circuit. And a limit control switch for opening an electric motor drive circuit in conjunction with an emergency stop switch and / or a brake operation, which is connected to the relay control circuit in series. A normally open / push button switch for maintaining the third speed is inserted in a relay control circuit for operating each contact of the motor drive circuit so as to drive the motor at the third speed, and a relay is provided in series with the switch. Normally open the relay
This is achieved by a traveling speed control device for a cargo handling vehicle, characterized in that a contact is connected in parallel with the push button switch to form a self-holding circuit of the relay.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

In order to clarify the features of the present invention, a speed control device for a low lift type cargo handling vehicle according to the prior art will be described first. As shown in FIG. 2, the low lift type cargo handling vehicle 1 includes a handle lever 2 provided at a rear portion thereof, and The vehicle is controlled by the driver's driving operation of the gear shift lever 4 attached to the control handle portion 3 provided on the upper portion of this and the button switch 6 of the control switch portion 5. The handle lever 2 is adapted to brake the vehicle by rotating the handle lever 2 forward or backward. As shown in FIG. 2, the speed change lever 4 is provided at the base of the grip 7 projecting on both sides of the control handle portion 3, and can be operated by the thumbs of the thumb to operate from the low speed first speed to the middle speed second speed and high speed. The third
When it is moved to a position corresponding to speed and the operating force is released, it is configured to return to the original position by the biasing force of the spring.

Further, as will be apparent from the circuit configuration described later, in order to maintain the third speed, not only is the gear shift lever 4 set to the position corresponding to the third speed described above, but also the control switch section as shown in FIG. It is necessary to keep pressing the third speed maintaining push button switch 6 provided on the No. 5 vehicle. This is a structure provided from a safety point of view, and when the push button switch 6 is opened, it is immediately returned to the second speed state.

This control circuit of the prior art will be described with reference to FIG. 4, but the basic part thereof is used as it is in the circuit configuration of the present invention described later.

In FIG. 4, a motor 10 for traveling the vehicle is driven by power supplied from a battery 11. First, by inserting the main key, the key switch SW _K is closed, and then by setting the speed change lever 4 to the first speed position, the switch SW _F linked to this is closed and the relay M _F is excited. Therefore, the contact _{F of the} relay M _F is switched from the state shown in the figure to the state shown by the dotted line, and current is supplied from the battery 11 to the motor 10 through the coil CL in the direction of the arrow.
This is the first speed running state. In the figure, LS _B is a limit switch that opens the circuit when the above-mentioned handle lever 2 is operated to apply a brake, and SW _SF is an emergency stop switch provided in the operation unit 3. Both are closed.

Next, when the speed change lever 4 is set to the second speed position,
The switch SW ₁ interlocked with this is closed, and the delay circuit DL ₁ energizes the relay M ₁ after a certain time delay. Thus a contact ₁ of the relay M ₁ is closed, the motor 10 since the current flowing through the resistor R ₁ to date is supplied to the motor 10 by bypassing it is driven further in a high speed. This is the second speed running state. The reason why the delay circuit DL is provided is because of safety considerations so that the second speed state does not occur at the same time when the shift lever 4 is operated.

Next, when the shift lever 4 is set to the third speed position,
The switch SW ₂ interlocking with this is closed, and in this state, the push button switch SW _H connected in series with the switch SW ₂ is further connected.
When you press to close the circuit, delay circuit DL ₂
Through the energized relay M _2, whereby the relay M ₂
The a-contact _{2 of} is closed, and the current flowing only in the coil CL until now is shunted to the resistor R ₂ connected in parallel with it.
The magnetic flux of the coil CL decreases and the rotation speed of the motor 10 increases. This is the third speed running state. In this case, it will be easily understood that when the operation of pressing the push button switch SW _H is stopped, the circuit is opened immediately and the excitation of the relay M ₂ is released, so that the state of the second speed is restored.

As mentioned at the beginning, although such a structure is brought about from the viewpoint of safety, it is considerably laborious to keep pressing the push button switch SW _H during driving, so that it is not necessary in the present invention. To solve this problem, a circuit as shown in FIG. 1 is used. Description of parts of this circuit that overlap with those of the conventional device shown in FIG.
Only the parts specific to the present invention will be described in detail.

In the present invention, the circuit leading to the battery 11 is branched from between the third speed maintaining push button switch SW _H and the delay circuit DL ₂ in the exciting circuit of the relay M ₂ and this circuit is connected in series with the switch SW _H. The relay LY is connected, and the a contact () of the relay LY is connected in parallel with the switch SW _H , thereby forming a self-holding circuit of the relay LY.

As a result, when the third speed maintaining push button switch SW _H is once pushed to make the circuit conductive at the beginning of the third speed running, the relay LY is excited by this and the a contact ▲ ▼ remains closed as it is. Is held in the switch
You no longer need to press and hold SW _H. In the figure, reference numeral 12 is a back electromotive prevention diode for circuit protection.

It is obvious that in order to release the third speed state, the shift lever 4 is returned to open SW ₂ , the brake is operated to open the limit switch LS _B , or the emergency stop switch SW _SF is pressed.

1 and 4, SW _R represents a reverse drive switch, and the circuit is closed by setting the speed change lever 4 from the neutral position to the direction opposite to the first speed position to close the relay M _R.
And its contact ( _R) to actuate the direction of the current flowing through the coil CL in the opposite direction to that in forward movement, thereby having the function of reversing the motor 10.

<Effects of the Invention> As described in detail above, according to the present invention, when the push button switch is temporarily pushed when the highest traveling speed is required in the low lift type cargo handling vehicle, the third self-holding circuit of the relay is used. Since the high speed circuit state is maintained as it is, there is no need to continue pushing the push button switch as in the past.
Driving operation becomes easy. To cancel this state, the brake is operated to turn off the limit switch, or the speed change lever is returned to the second or lower speed position, so that the self-holding circuit is immediately opened.

[Brief description of drawings]

FIG. 1 is a control circuit surface of a vehicle traveling speed according to the present invention, FIG. 2 is a schematic perspective view of a low lift type cargo handling vehicle to which the present invention is applied, and FIG. 3 is a perspective view of an operating portion of the vehicle of FIG. 4 and FIG. 4 are control circuit diagrams of the conventional device. DESCRIPTION OF SYMBOLS 1 ... Cargo vehicle, 2 ... Handle lever, 3 ... Control handle part, 4 ... Shift lever, 5 ... Control switch part, 6 ... 3rd speed maintenance push button switch, 7 ... Grip, 10 ... Motor, 11 ... Battery .

Claims (1)

[Scope of utility model registration request] 1. A motor drive circuit for driving a traveling motor from a low speed to a high speed at a first speed, a second speed, and a third speed according to an operation position of a shift lever, and opening / closing operations of respective contacts of the motor drive circuit. In a speed control device for a low lift type cargo handling vehicle, which further comprises a relay control circuit for operating the emergency stop switch and / or a limit switch which opens a motor drive circuit in conjunction with a brake operation in series with the relay control circuit. , Insert a normally open / push button switch for maintaining the third speed into a relay control circuit for operating each contact of the motor drive circuit so as to drive the motor at the third speed, and connect a relay in series with this switch. A traveling speed of a cargo handling vehicle, characterized in that a normally open contact of the relay is connected in parallel with the push button switch to form a self-holding circuit of the relay. The control device.