JPH06492B2 - Breaking device for forklift trucks - Google Patents

Description

The present invention relates to a clutch (particularly a torque converter) by operating a shift lever from a forward speed to a reverse speed or from a reverse speed to a forward speed without performing a brake operation. ) In the opposite direction to generate a braking force on the wheels of the drive system (hereinafter referred to as select brake operation),
The present invention relates to a brake device for a forklift truck that uses a hydraulic pressure of a lift cylinder to operate a brake means provided on a wheel.

(Prior Art) A conventional brake device for a forklift truck is, for example, 99 of “Introduction of Nissan Service Weekly Report 413 F03 type car” (published by Nissan Motor Co., Ltd. in March 1980).
The ones described in pages 103 to 103 are known.

As shown in FIG. 7, this conventional device is provided on a wheel and a master cylinder 02 that generates hydraulic pressure in response to a depression force on a brake pedal 01, and operates by receiving the hydraulic pressure from the master cylinder 02. And a drum brake (brake means) 03 for generating a braking force.

(Problems to be solved by the invention) However, in such a conventional brake device for a forklift truck, since the number of times of use in forward and backward movement is substantially the same, the driving vehicle brakes when changing the traveling direction of the vehicle. Pedal operation is cumbersome, and the traveling direction of the vehicle is often changed by the select brake operation, which causes the following problems.

 The braking force generated on the wheels is small.

The engine is overloaded and may stall.

Similar to the engine, an excessive load is applied to the clutch (particularly the torque converter) and the engine drive system, so that the clutch (particularly the torque converter) may be overheated or the engine drive system may be damaged.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this object, the present invention provides the following solving means. .

The solution means of the present invention will be described with reference to the conceptual diagram of the claims shown in FIG. 1. A shift lever 1 for switching between a forward speed and a reverse speed, and a driving force passing through an engine 2 and a clutch 3 are changed depending on a switching position of the shift lever 1. In a forklift vehicle equipped with an engine 2 drive system that transmits to the wheels 4 by means of a lever, lever position detecting means 5 for detecting whether the lever position of the shift lever 1 is a forward gear or a reverse gear, an oil chamber of a lift cylinder 6, and the wheel. The actuator 8 which is set in the middle of the oil passage communicating with the brake means 7 of 4 and opens the oil passage by a control signal from the outside, and the lever position detecting means 5 from the forward stage to the reverse stage or the reverse stage of the shift lever 1. Control signal (c) that causes the hydraulic pressure from the lift cylinder 6 to act on the brake means 7 when a signal (s) indicating a shift operation from the vehicle to the forward gear is input. And control means 9 for outputting to the actuator 8 by a predetermined time, characterized in that the provided.

(Operation) When the vehicle is stopped by the select brake operation that shifts the shift lever 1 from the forward gear to the reverse gear or from the reverse gear to the forward gear, the control means 9 shifts the gear shift of the shift lever 1 from the lever position detection means 5. Based on the input of the signal (s) indicating the operation, the control signal (c) that causes the hydraulic pressure by the lift cylinder 6 to act on the brake means 7 is output to the actuator 8 for a predetermined time.

As a result, in addition to the braking force by the select brake operation, the braking force can be generated on the wheels 4 by the brake means 7 for a predetermined time by the hydraulic pressure by the lift cylinder 6.

Further, since the brake means 7 is operated by the hydraulic pressure of the lift cylinder 6, it is not necessary to add a dedicated hydraulic pressure generating device, and the hydraulic pressure of the lift cylinder 6 is increased when the load is loaded, so that the load is loaded. It is possible to obtain the braking force according to the increase in the weight of the vehicle when the vehicle is placed.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

First, the structure of the first embodiment shown in FIGS. 2 to 4 will be described.

As shown in FIG. 2, the brake device A for a forklift truck of the first embodiment has a transmission 10, a shift lever 20, a lift cylinder 30, a lift oil passage 40, a master cylinder 50, a wheel cylinder (brake means) 6, as shown in FIG.
0, 60, and an automatic braking device 70.

The transmission 10 includes a torque converter 12, which is a clutch provided in a drive system of an engine 11 and transmits an engine output with a torque increasing action, and a transmission 13 having a gear ratio of one forward speed and one reverse speed. I have it.

The shift lever 20 moves the transmission 13 to the neutral position (N).
And a lever for gear shift operation between the forward gear position (F) and the reverse gear position (R). When the select brake is operated, the gear shift operation to the shift lever 20 causes reverse torque to act on the torque converter 12, A braking force is generated on the wheels 100, 100 of the drive system without performing a braking operation.

The lift cylinder 30 has a fork 31 due to hydraulic pressure.
The lift cylinder 30 includes a piston 33 that moves up and down by hydraulic pressure in a cylinder 32,
A push rod 34 connected to the piston 33, a chain 35 having one end attached to the fork 31 and the other end attached to the cylinder 32, and provided at the end of the push rod 34, and the chain 35 is hung around. And a chain sprocket 36 that is installed.

Incidentally, the lift cylinder 30 is always even during unloaded not put luggage on the fork 31, the push rod 34 and the chain sprocket 36 such as a hydraulic in a cylinder 32 of 10kg / cm ² ~15kg / cm ² by the weight of the (static Pressure), and a hydraulic pressure of about 100 kg / cm ² is generated during loading.

One end of the lift oil passage 40 is connected to the lift cylinder 30 and the other end is connected to the reserve tank 41, and a connector 42, a switching valve 43, and an oil pump 44 are provided on the way.

The oil pump 44 is a pump that is driven by the engine 11 and pressurizes the hydraulic oil a in the reserve tank 41 to supply it to the lift cylinder 30 when the switching valve 43 is opened.

The switching valve 43 is a valve that is opened and closed by operating the lift lever 45, and a lift-side drain oil passage 46 communicating with the reserve tank 41 is connected to the switching valve 43.

At the neutral position of the switching valve 43, the oil pump 44
The hydraulic oil a sent from the lift oil passage 40 to the inside of the reserve tank 41 is circulated by the drain oil passage 46a.

The master cylinder 50 converts the pedaling force applied to the brake pedal 51 into hydraulic pressure. The master cylinder 50 includes a piston 53 that pressurizes the brake fluid b in the cylinder 52 when the brake pedal 51 is depressed, and the piston 53. A push rod 54 that connects the brake pedal 53 to the brake pedal 51, and a return spring (not shown) that returns the piston 53 to the original position where it abuts the ring stopper 55 when the foot is released from the brake pedal 51. .

The wheel cylinder 60 is a pressure adjusting cylinder 8 described later.
The first brake fluid passage 61 and the second brake fluid passage 62 communicate with the master cylinder 50 via 7, and the brake shoes 63, 63 receive hydraulic pressure from the master cylinder 50.
When the wheel cylinder 60 is actuated, the brake shoes 63, 63 move the brake wheel 64.
The wheel 100 is pressed against the wheel 100 to generate a braking force on the wheel 100.

It should be noted that one end of the first brake fluid passage 61 is at the master cylinder 50.
The other end of the second brake oil passage 62 is connected to the pressure adjusting cylinder 87, one end of the second brake oil passage 62 is connected to the pressure adjusting cylinder 87, and the other end is connected to the wheel cylinders 60, 60 by the branch of the oil passage.

The automatic brake device 70 includes an automatic brake hydraulic circuit 8
0 and a hydraulic control device 90.

The automatic brake hydraulic circuit 80 controls the hydraulic pressure of the lift cylinder 30 when the select brake is operated.
This automatic brake hydraulic circuit 80 has an input side oil passage 82 whose one end is connected to the connector 42 and the other end is connected to the pressure reducing valve 81, and one end is connected to the pressure reducing valve 81 and the other end. Is connected to the solenoid valve 83, a first output oil passage 84, one end is connected to the solenoid valve 83, the other end is connected to the operation cylinder 85, a second output oil passage 86, and the first brake oil passage 61. And the second brake fluid passage 6
2 by master cylinder 50 and wheel cylinder 60
And a pressure regulating cylinder 87 communicating with the pressure regulating cylinder 87.
And a connecting mechanism 88 for connecting the push rod 87a of the operating cylinder 85 and the push rod 85a of the operating cylinder 85.

The pressure reducing valve 81 is a valve that reduces the hydraulic pressure of the lift cylinder 30 input from the input side oil passage 82 and outputs it to the first output side oil passage 84.

The pressure reducing valve 81 reduces the hydraulic pressure Pi of the lift cylinder 30 under the following conditions.

[I] When 0 ≦ Pi ≦ P ₁ P ₀ = Pi [ii] When Pi> P ₁ P ₀ = αPi + P ₁ Pi; Input hydraulic pressure P ₀ ; Output hydraulic pressure P ₁ ; 15 kg / cm ² α = 0.2 The solenoid valve 83 is a pressure reducing valve 81 when the valve is opened.
The brake side drain oil passage 89 connected to the reserve tank 41 is connected to the solenoid valve 83.

When the solenoid valve 83 is closed, the brake cylinder drain oil passage 89 connects the operation cylinder 85 and the reserve tank 41.

The operation cylinder 85 receives the hydraulic pressure from the lift cylinder 30 when the solenoid valve 83 is opened and receives the piston 8
5b operates, push rod 85a and connecting mechanism 88
Transmit power to.

In the pressure adjusting cylinder 87, when the pressing force is input to the piston 87b from the connecting mechanism 88 via the push rod 87a, the piston 87b operates, and the pressing force is converted into the hydraulic pressure of the brake fluid b and supplied to the wheel cylinder 60. To do.

The piston 87b of the pressure adjusting cylinder 87 has a return spring (not shown) when the pressing force is not input.
Is pressed against the ring stopper 87c to regulate the position.

The hydraulic control device 90 uses the vehicle speed sensor 9 as an input unit.
1, shift lever switch (lever position detection means) 92
And a controller 93 as a control means, and a valve solenoid 94 for operating the solenoid valve 83 as an actuator.

The vehicle speed sensor 91 is a sensor that detects the vehicle speed V and outputs a vehicle speed signal (v).

The shift lever switch 92 is a shift operation signal due to a signal change of ON-OFF-ON when the shift lever 20 is switched from the forward speed (F) to the reverse speed (R) or from the reverse speed (R) to the forward speed (F). (S) is a switch for outputting the shift lever switch 92, as shown in FIG.
The forward gear switch 92a that outputs an ON signal when the lever position of the shift lever 20 is in the forward gear (F), the neutral position switch 92b that outputs an OFF signal when the lever position is in the neutral position (N), and the reverse gear (R). And a reverse switch 92c that outputs an ON signal at the time.

The controller 93 inputs the vehicle speed signal (v) from the vehicle speed sensor 91 and the shift operation signal (s) from the shift lever switch 92, and when the vehicle speed V is equal to or higher than the set vehicle speed V ₀ , the select brake operation is performed. A control signal (C ₁ ) for the valve solenoid 94 and the monitor lamp 95,
This controller 93 is a control circuit that outputs (C ₂ ).
Is a comparison circuit 93a and a delay circuit 9 as shown in FIG.
3b and 93c, and AND circuits 93d and 93e.

The comparison circuit 93a includes a vehicle speed sensor 91 and an AND circuit 93e.
, And compares the vehicle speed V with the set vehicle speed V ₀ to obtain V ≧
It is a circuit that outputs an ON signal when V ₀ .

In the embodiment, V ₀ = 8 km / h is set.

The delay circuit 93b is connected to the reverse gear switch 92c and the AND circuit 93d to move the shift lever 20 to the reverse gear (R).
To the forward speed (F), the reverse speed switch 9
This circuit delays the ON signal from 2c by t ₀ and outputs it.

In the embodiment, t ₀ = 0.2 _sec is set.

The AND circuit 93d includes a shift lever switch 92 and an AN.
This circuit is connected to the D circuit 93e and outputs an ON signal to the AND circuit 93e when both ON signals from the reverse stage switch 92c and the forward stage switch 92a are input.

That is, the AND circuit 93d is a circuit that determines whether the shift operation in which the shift lever 20 is switched from the reverse gear (R) to the forward gear (F) is a normal gear shift operation or a select brake operation. Outputs an ON signal during brake operation (when gear shifting is performed within 0.2 _sec ).

Incidentally, 93b is a delay circuit which outputs an ON signal for a predetermined time (0.2 _sec ) when the backward gear (R) is switched to the forward gear (F).

The AND circuit 93e includes a comparison circuit 93a and an AND circuit 93e.
It is a circuit that inputs both ON signals from d and outputs an ON signal to the delay circuit 93c.

The delay circuit 93c is a circuit that inputs the ON signal from the AND circuit 93e, delays it by the time T ₀ , and outputs the ON signal to the valve solenoid 94 and the monitor lamp 95.

In the embodiment, T ₀ = 1.5 _sec is set.

The valve solenoid 94 is an actuator that receives a control signal (c ₁ ) as an ON signal from the controller 93 and operates for a time of T ₀ to open the solenoid valve 83.

The monitor lamp 95 is turned on from the controller 93.
It is a lamp which is supplied with a control signal (c ₂ ) as a signal and is turned on for a time of T ₀ , and is attached to a meter panel (not shown).

Next, the operation of the first embodiment will be described.

(B) During normal brake operation When the brake pedal 51 is depressed, the push rod 54
As a result, the piston 53 is pushed and moves to press the brake fluid b in the cylinder 52.

As a result, hydraulic pressure corresponding to the amount of depression of the brake pedal 51 is generated in the master cylinder 50.

The hydraulic pressure is from the first brake fluid passage 61 to the pressure adjusting cylinder 8.
7 → wheel cylinder 6 through second brake fluid passage 62
It is transmitted to 0,60.

At this time, the piston 87b of the pressure adjusting cylinder 87 is pressed by the hydraulic pressure, but the piston 87b is not pressed and moved because the position is regulated by the ring stopper 87c. Therefore, the piston 87b moves. Therefore, the hydraulic pressure is not reduced in the pressure adjusting cylinder 87,
The hydraulic pressure of the master cylinder 50 is directly transmitted to the wheel cylinder 60.

Then, the wheel cylinder 60 operates by receiving hydraulic pressure to open the brake shoes 63, 63, and the brake shoe 6
3, 63 are pressed against the brake wheel 64, and a braking force is generated on the wheel 100.

(B) During select brake operation (V <V ₀ ) If the shift lever 45 is switched from the reverse speed (R) to the forward speed (F) and the select brake operation is performed without performing the normal brake operation described above, Reverse torque acts on the torque converter 12 to generate braking force on the wheels 100 of the drive system.

When the vehicle speed V is equal to or lower than the set vehicle speed V ₀ , the vehicle can be stopped with a small braking force, so that the torque in the opposite direction can be applied to the torque converter 12 to reduce the load on the drive system and perform braking.

(C) During select brake operation (V ≧ V ₀ ) When the select brake operation is performed when V ≧ V ₀ , the controller 93 sends control signals (c ₁ ) and (c ₂ ).
Is output to the valve solenoid 94 and the monitor lamp 95 for a period of time T ₀ , the valve solenoid 94 is operated by inputting a control signal (c ₁ ) to open the solenoid valve 83, and the monitor lamp 95 is controlled. Signal (c
₂ ) is input to display the opening operation of the lighting solenoid valve 83.

When the solenoid valve 83 is opened, the hydraulic pressure in the lift cylinder 30 changes from the lift oil passage 40 to the input side oil passage 8.
It is transmitted to the operation cylinder 85 through the 2 → pressure reducing valve 81 → first output side oil passage 84 → solenoid valve 83 → second output side oil passage 86.

At that time, the hydraulic pressure of the lift cylinder 30 is 15 kg /
When the pressure is larger than cm ² , the pressure is reduced by the pressure reducing valve 81.

As a result, the piston 85b of the operation cylinder 85 operates by receiving hydraulic pressure to push the connecting mechanism 88 by the push rod 85b, and the connecting mechanism 88 pushes the push rod 87a of the pressure adjusting cylinder 87.

Therefore, the piston 87b is pushed and moved by the push rod 87a, presses the brake fluid b, and hydraulic pressure is generated in the pressure adjusting cylinder 87.

Then, the hydraulic pressure is transmitted to the wheel cylinders 60, 60 by the second brake fluid passage 62.

At this time, the hydraulic pressure is also transmitted to the master cylinder 50 by the first brake fluid passage 61 and presses the piston 53. However, since the position of the piston 53 is regulated by the ring stopper 55, the piston 53 does not move by being pushed. Therefore, the hydraulic pressure is not reduced in the master cylinder 55 by the movement of the piston 55, and
The hydraulic pressure of 7 is transmitted to the wheel cylinder 60 as it is.

Therefore, the wheel cylinder 60 operates and the braking force is generated on the wheel 100 for T ₀ time.

After that, when the time T ₀ has elapsed, the output of the control signals (c ₁ ) and (c ₂ ) from the controller 93 is stopped, the valve solenoid 94 is deactivated, and the solenoid valve 83
Is closed, and the monitor lamp 95 is turned off.

Then, by closing the solenoid valve 83, the excess hydraulic oil a in the operating cylinder 85 is returned to the reserve tank 41 by the brake side drain oil passage 89, and the hydraulic pressure in the operating cylinder 85 is reduced.

As a result, the pressing force of the connecting mechanism 88 against the piston 87b of the pressure adjusting cylinder 87 is released, and the piston 87b is returned to the original position where it abuts the ring stopper 87c by the return spring (not shown), and the pressure adjusting cylinder 8
The hydraulic pressure in 7 is reduced.

Therefore, the operation of the wheel cylinder 60 is stopped and the wheel 10
The braking force generated by the wheel cylinder 60 at 0 is eliminated and the forward movement system of the vehicle is prepared.

As described above, in the brake device A of the forklift truck of the first embodiment, the vehicle speed V is the set vehicle speed V _0.
When the select brake operation is performed at the above times, in addition to the braking force by the select brake, the wheel cylinder 6
0, the braking force can be generated on the wheel 100 for the time T ₀ .

Further, since the wheel cylinder 60 is operated by the hydraulic pressure of the lift cylinder 30, it is not necessary to separately provide a dedicated hydraulic pressure generating device, and the hydraulic pressure of the lift cylinder 30 becomes large when the luggage is loaded, and the wheel cylinder 6
The braking force of 0 can be increased, and by this,
It is possible to obtain the braking force according to the increase in the weight of the vehicle when the luggage is placed.

Further, since the hydraulic circuit for hydraulic oil a and the hydraulic circuit for brake oil b are separated, troubles due to mixing of hydraulic oil a and brake oil b do not occur.

By the way, as shown in the time chart of FIG. 4, comparing a vehicle equipped with the automatic braking device 70 (shown by a solid line) and a vehicle not equipped with the automatic braking device 70 (shown by a dotted line), the automatic braking device is operated when the select brake is operated. The fact that 70 operates for the time T ₀ causes the following differences.

First, comparing the vehicle speed V with the vehicle speed signal (v), both the solid line and the dotted line become V = 0 after T ₂ hours from the time when the select brake is operated, but the solid line decreases sharply compared with the dotted line. , Shows that the braking force is high.

Next, comparing the actual vehicle speeds, the solid line shows V = 0 after T ₂ ′ time from the time of selecting brake operation, but the dotted line shows V = 0 after T ₂ ″ time.

This characteristic indicates that due to T ₂ ′ <T ₂ ″, the reverse rotation of the wheels was reduced in the vehicle with the device compared to the vehicle without the device.

Next, comparing the axle torques, both the solid line and the dotted line show the maximum torque T ₁ hours after the select brake operation, but the peak value of the solid line is much smaller than that of the dotted line.

This characteristic indicates that the vehicle with the device has a smaller load applied to the engine 11 and the torque converter 12 at the time of select braking than the vehicle without the device.

Next, a second embodiment shown in FIGS. 5 and 6 will be described.

In the description of the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The description of the same operation will be omitted.

This embodiment is an example in which the set time T ₀ is a variable set time T ₀ ′ that increases in proportion to the vehicle speed V.

A time setting circuit 200 outputs a variable setting time T ₀ ′ according to the vehicle speed signal (v) from the vehicle speed sensor 91 to the delay circuit 93c.

Incidentally, FIG. 6 shows a relational expression between the vehicle speed V and the variable set time T ₀ ′. The relief pressure P _max is preferably set to 185 kg / cm ² .

Therefore, the time when the automatic brake device 70 operates is set to the vehicle speed V.
Can be made variable according to the vehicle speed V
It is possible to prevent the operation of the automatic braking device 70 from continuing even after V becomes 0.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention can be applied even if there is a design change or the like within a range not departing from the gist of the present invention. included.

For example, although the example in which the torque converter is used as the clutch is shown in the embodiment, it is needless to say that the present invention is not limited to this and can be applied to a manual transmission type.

Further, in the embodiment, the example in which the hydraulic pressure of the lift cylinder is converted to the hydraulic pressure of the brake system to indirectly act on the wheel cylinder has been shown, but the working oil of the lift cylinder may be directly acted on the wheel cylinder. Good.

Further, in the embodiment, the example of the select brake operation by the gear shift operation from the reverse gear to the forward gear is shown, but it is also applicable to the select brake operation by the gear shift operation from the forward gear to the reverse gear.

(Effects of the Invention) As described above, in the brake device for a forklift truck of the present invention, when the vehicle is stopped by the select brake operation, in addition to the braking force by the select brake operation, the predetermined time has elapsed after the select brake operation. Since only the braking means can generate the braking force, the load applied to the engine, the clutch, and the engine drive system can be reduced, and the engine stall, the clutch, and the engine drive system can be prevented from being damaged.

Further, since the brake means is operated by the hydraulic pressure of the lift cylinder, it is not necessary to add a dedicated hydraulic pressure generating device, and the hydraulic pressure of the lift cylinder is increased when loading the cargo, and the operating force of the brake means is increased. To increase
The effect that the braking force can be obtained according to the increase in the weight of the vehicle when the luggage is placed is obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a brake system for a forklift truck according to the present invention, FIG. 2 is a hydraulic circuit diagram showing the entire first embodiment device of the present invention, and FIG. 3 is a control of the first embodiment device of the present invention. FIG. 4 is a logic block circuit diagram showing the main part of the system, FIG. 4 is a time chart diagram showing each characteristic of the device of the first embodiment of the present invention, and FIG.
FIG. 6 is a logic block circuit diagram showing a main part of a control system of a brake system for a forklift truck according to a second embodiment of the present invention, and FIG. 6 is a T ₀ ′ -V characteristic showing a relationship between a variable set time T ₀ ′ and a vehicle speed V. FIG. 7 is a hydraulic circuit diagram showing a conventional brake device for a forklift truck. 1 ... Shift lever 2 ... Engine 3 ... Clutch (torque converter) 4 ... Wheel 5 ... Lever position detection means 6 ... Lift cylinder 7 ... Braking means 8 ... Actuator (s) ... Signal (c) ... Control signal

Claims (1)

[Claims] 1. A forklift vehicle comprising a shift lever for switching between a forward speed and a reverse speed, and an engine drive system for transmitting a driving force passing through an engine and a clutch to wheels according to a switching position of the shift lever. The lever position detecting means for detecting whether the lever position of the lever is forward or backward, and the oil passage provided between the oil chamber of the lift cylinder and the braking means of the wheel are provided in the middle of the oil passage. When a signal indicating a shift operation from the forward shift stage to the reverse shift stage or the reverse shift stage to the forward shift stage of the shift lever is input from the actuator for opening the road and the lever position detection means, the hydraulic pressure by the lift cylinder is applied to the brake means. Control means for outputting a control signal to the actuator for a predetermined time, and a fork characterized by the following: Brake system for lift trucks.