JP2002106698A - Carrying vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrying vehicle capable of automatically selecting a change gear ratio when starting in response to a load to be applied to a deck. SOLUTION: A car body is provided with a deck to be elevated by a cylinder device, an automatic transmission 21, a control unit 74 for controlling the automatic transmission 2, and a hydraulic sensor 17 for detecting the hydraulic pressure inside of the cylinder device so as to obtain a load to be applied to the deck. When the detected hydraulic pressure is a constant value or more, the control unit 74 selects a forward first speed of the automatic transmission 21 when starting the vehicle. When the detected hydraulic pressure is less than the constant value, the control unit 74 selects a forward second speed of the automatic transmission 21 when starting the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission vehicle having a carrier for supporting a load.

[0002]

2. Description of the Related Art Conventionally, as an automatic transmission type transport vehicle,
For example, as shown in FIG. 13, there is a vehicle body 81 provided with a carrier 83 for supporting a load 82 and an automatic transmission 84 (automatic transmission). A selector lever 86 is provided in the cab 85.

According to this, when starting the transport vehicle 87, the driver sets the selector lever 86 to D (drive).
Switch to the range and depress the accelerator. This allows
First, the transport vehicle 87 starts with the automatic transmission 84 in the first speed, and thereafter, when the traveling speed of the transport vehicle 87 reaches a predetermined speed, the automatic transmission 84 is automatically switched to the second speed, and As the traveling speed of the vehicle 87 increases, the automatic transmission 84 automatically switches from third speed to fourth speed.

In the above-described conventional type, the gear ratio is always the highest regardless of whether the carrier 83 is empty (no load) or when the load 82 is loaded on the carrier 83 (loaded). The transport vehicle 87 starts in a large first speed state. Normal,
When the load 82 is loaded on the loading platform 83, a large torque is required at the time of starting, so that the first gear ratio is set accordingly.

[0005]

However, in the above-mentioned conventional type, when the carrier 83 is empty and the transport vehicle 87 starts at the first speed, excessive torque is generated more than necessary. There is a problem that it takes time to increase the traveling speed of the transport vehicle 87 by stepping on the vehicle.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transport vehicle capable of automatically changing a speed ratio at the time of starting according to the magnitude of a load acting on a carrier.

[0007]

In order to achieve the above object, a first aspect of the present invention is a transport vehicle provided with a body for supporting a load and an automatic transmission on a vehicle body. Load detecting means for detecting a load to be performed, and a control unit for controlling the automatic transmission based on the load detected by the load detecting means, wherein the control unit is provided when the detected load is equal to or more than a predetermined value. When the vehicle is started, the automatic transmission is switched to the first speed, and when the detected load is less than a predetermined value, the automatic transmission is switched to the second speed when the vehicle starts.

According to this, when the load detected by the load detecting means is equal to or more than a predetermined value, the transport vehicle starts with the automatic transmission in the first speed. As a result, the gear ratio becomes the largest and a large torque is generated at the time of starting,
Even when the bed is full of loads, there is no shortage of torque.

When the load detected by the load detecting means is less than a predetermined value, the transport vehicle starts with the automatic transmission switched to the second speed. As a result, the gear ratio becomes smaller than in the case of the first speed, and the generated torque becomes 1
Although the speed is smaller than the speed, the traveling speed of the transport vehicle can be increased in a short time by stepping on the accelerator.
Thereby, speeding up at the time of starting can be achieved.

According to the second aspect of the present invention, the loading platform is configured to be movable up and down by a cylinder device, and a pressure sensor for detecting the pressure of the working fluid in the cylinder device is used as the load detecting means.

According to this, when a load is loaded on the carrier, a load acts on the carrier, and the pressure of the working fluid in the cylinder device increases according to the magnitude of the load. Therefore, the magnitude of the load acting on the carrier is obtained based on the pressure value detected by the pressure sensor.

[0012]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. As shown in FIGS. 8 to 11, reference numeral 1 denotes a transport vehicle that transports a load 2 such as a coil body. The vehicle body 3 of the transport vehicle 1 is divided into two parts by a front body part 5 having a pair of left and right front wheels 4 and a rear body part 7 having a pair of left and right rear wheels 6. The front vehicle body portion 5 and the rear vehicle body portion 7 are connected via a connecting device 8 so as to be relatively pivotable about a longitudinal axis 9. In addition, a steering cylinder device 10 is provided in a portion of the coupling device 8.

The rear body 7 includes a carrier 12 for supporting the load 2 via a pallet 11, a pair of left and right front lift cylinder devices 13 and a pair of left and right rear lift cylinder devices 14 for raising and lowering the carrier 12. , A cover body 24 are provided.

The loading platform 12 has a pair of left and right load supporting frames 12a and 12b, and is formed in a U-shape in plan view with upper, lower, and rear portions opened. The main body 13a of the front lift cylinder device 13 is attached to the front of the rear body portion 7, and the tip of the piston rod 13b is
2 at the front. Further, a main body 14a of the rear lift cylinder device 14 is attached to a rear part of the rear vehicle body part 7, and a distal end of the piston rod 14b is connected to a rear part of the carrier 12 via a link 15 that can rotate vertically.
As shown by the solid line in FIG. 7, the protruding piston rod 13b and piston rod
2 rises to the upper limit position, and as shown by the imaginary line in FIG.
By retreating, the carrier 12 descends to the lower limit position.

As shown in FIG. 7, a main body 13a of one of the left and right front lift cylinder devices 13 has a hydraulic pressure sensor 17 for detecting the oil pressure on the tail side inside the main body 13a.
Is provided. The hydraulic pressure sensor 17 is an example of a load detecting means, and the hydraulic pressure on the tail side of the front lift cylinder device 13 increases in proportion to the magnitude of the downward load acting on the carrier 12. The magnitude of the load acting on the carrier 12 is determined based on the hydraulic pressure value.

As shown in FIG. 11, insertion portions 16 are formed below both sides of the pallet 11, and
The two load supporting frames 12a and 12b can be inserted into and removed from the insertion portions 16 from the rear at the lower limit position.

The front body 5 has a driver's cab 19
The engine 20 for rotating the front wheels 4, a torque converter (not shown), an automatic transmission 21 (automatic transmission), and the traveling of the transport vehicle 1 based on the rotation speed of the axle of the front wheels 4. A speed sensor 18 for detecting a speed is provided.

As shown in FIG. 5, a steering wheel 22, a selector lever 23 for switching a selector of the automatic transmission 21, an accelerator, a brake, and the like are provided in the cab 19.

The selector lever 23 has a D (drive) range when switched to the front, an R (reverse) range when switched to the rear, and an N (neutral) range when switched to the middle. As shown in FIG. 6, a rotary knob 2 is provided at the distal end of the selector lever 23.
5 are provided. The rotary knob 25 has the first speed
A rotation switching position corresponding to the fourth speed is set, and by rotating the rotary knob 25 to switch to the fourth speed position, automatic shifting is performed in the entire range of the first to fourth speeds.

The automatic transmission 21 is automatically provided with the first speed
A control valve mechanism 28 for switching to the fourth speed is provided. Next, the hydraulic circuit of the control valve mechanism 28 will be described.
That is, as shown in FIG.
The first-speed switching valve 31, the second-speed switching valve 32, the third-speed switching valve 33, the fourth-speed switching valve 34, the forward switching valve 35, the reverse switching valve 36, A first pilot valve 38 for switching the valve 31; a second pilot valve 39 for switching the second-speed switching valve 32;
A fourth pilot valve 41 for switching the fourth speed switching valve 34, a forward pilot valve 42 for switching the forward switching valve 35,
A reverse pilot valve 43 for switching the reverse switching valve 36 is provided.

A supply line 51 for supplying hydraulic oil (an example of a working fluid) in a tank 45 to each of first- to fourth-speed clutches 47 to 50 by a pump 46 is provided in the hydraulic circuit.
A supply line 54 for supplying hydraulic oil to the forward clutch 52 and the reverse clutch 53;
, And pilot pressure supply lines 61 and 62 for supplying pilot pressure to the forward switching valve 35 and the reverse switching valve 36.

The first- to fourth-speed switching valves 31 to 34, the forward switching valve 35 and the reverse switching valve 36 are
This is a port 2 position switching valve, which is switched to one switching position A by the force of the spring 64, and further switched to the other switching position B by the pilot pressure. The first to fourth pilot valves 38 to 41, the forward pilot valve 42, and the reverse pilot valve 43 are spring-offset electromagnetic three-port two-position switching valves. It is switched to the switching position a and further switched to the other switching position b by the magnetic action of each of the solenoids 66-71.

Also, as shown in FIG.
Is provided with a control unit 74 for controlling the solenoids 66 to 71 of the automatic transmission 21 based on the switching signal of the selector lever 23, the detection signal of the hydraulic pressure sensor 17, and the detection signal of the speed sensor 18. . Hereinafter, the operation of the control valve mechanism 28 will be described.

(1) As shown in FIG. 3, when the control unit 74 turns on (energizes) the solenoid 66 of the first pilot valve 38, the first pilot valve 38 is switched to the other switching position B, and the operation is started. Oil is pilot pressure supply line 5
5 and 56, the first-speed switching valve 31 is switched to the other switching position B. As a result, the hydraulic oil flows through the supply line 51, the fourth speed switching valve 34 → the third speed switching valve 33 → 2
The first-speed switching valve 31 is supplied to the first-speed clutch 47 through the first-speed switching valve 32, whereby the first-speed switching is performed.

(2) As shown in FIG. 4, when the control unit 74 turns on (energizes) the solenoid 67 of the second pilot valve 39, the second pilot valve 39 is switched to the other switching position B, and the operation is started. Oil is pilot pressure supply line 5
5 and 57, the second-speed switching valve 32 is switched to the other switching position B. As a result, the operating oil flows through the supply line 51, passes through the fourth-speed switching valve 34 → the third-speed switching valve 33, and is supplied from the second-speed switching valve 32 to the second-speed clutch 48. Speed.

(3) Similarly, when the control unit 74 turns on (energizes) the solenoid 68 of the third pilot valve 40, the third pilot valve 40 is switched to the other switching position B, and the operating oil is set to the pilot pressure. Through the supply lines 55 and 58, the third-speed switching valve 33 is switched to the other switching position B. As a result, the hydraulic oil flows through the supply line 51, passes through the fourth-speed switching valve 34, and is supplied from the third-speed switching valve 33 to the third-speed clutch 49, thereby being switched to the third speed.

(4) Similarly, when the control unit 74 turns on (energizes) the solenoid 69 of the fourth pilot valve 41, the fourth pilot valve 41 is switched to the other switching position B, and the operating oil is changed to the pilot pressure. Flowing through the supply lines 55 and 59, the fourth speed switching valve 34 is switched to the other switching position B. As a result, the hydraulic oil flows through the supply line 51 and is supplied from the fourth-speed switching valve 34 to the fourth-speed clutch 50, whereby the fourth-speed is switched.

(5) As shown in FIG. 3, the controller 74 turns on (energizes) the solenoid 70 of the forward pilot valve 42.
As a result, the forward pilot valve 42 is switched to the other switching position B, the operating oil flows through the pilot pressure supply line 61, and the forward switching valve 35 is switched to the other switching position B. Thereby, the hydraulic oil is supplied to the supply line 5
4 and is supplied from the forward switching valve 35 to the forward clutch 52, whereby the mode is switched to the forward mode.

(6) Similarly, when the control unit 74 turns on (energizes) the solenoid 71 of the reverse pilot valve 43, the reverse pilot valve 43 is switched to the other switching position B, and the operating oil is changed to the pilot pressure. After flowing through the supply line 62, the reverse switching valve 36 is switched to the other switching position B. Thereby, the hydraulic oil flows through the supply line 54,
The vehicle is passed from the reverse switching valve 36 to the reverse clutch 53 without passing through the forward switching valve 35, and is switched to the reverse mode. Next, a method of transporting the load 2 together with the pallet 11 while the load 2 is placed on the pallet 11 will be described.

First, as shown by the imaginary line in FIG. 7, the piston rods 13b and 14b of the front and rear lift cylinder devices 13 and 14 are retracted, and the carrier 12 is lowered to the lower limit position. Then, the transport vehicle 1 is moved backward at a low speed, and as shown in FIG.
6, the two load supporting frames 12a and 12b of the loading platform 12 are inserted. Thereafter, as shown by the solid line in FIG. 7, the respective piston rods 13b and 14b are projected, and the carrier 12 is raised to the upper limit position. As a result, as shown by the solid lines in FIGS.
Lifted off the ground.

At this time, the hydraulic pressure on the tail side in the main body 13a of the left or right front lift cylinder device 13 is detected by the hydraulic sensor 1
7. Here, when the weight of the load 2 is heavy, the downward load acting on the loading platform 12 is large, and accordingly, the detected hydraulic pressure also increases.

As described above, when the load 2 is lifted together with the pallet 11 in a state where the transport vehicle 1 is stopped, and then the transport vehicle 1 is moved forward to transport the load 2, the driver in the cab 19 needs to be operated as shown in FIG. 5, the selector lever 2
Switch 3 to D range. As shown in FIG. 6, the rotary knob 25 of the selector lever 23 is normally set to a rotation switching position corresponding to the fourth speed.

In response to the switching signal from the selector lever 23, the control unit 74 switches the automatic transmission 21 to the forward mode as described in (5) above. Further, when the oil pressure detected by the oil pressure sensor 17 is equal to or more than a predetermined value, the control unit 74 executes the automatic transmission 2 as described in (1) above.
Change 1 to 1st gear. Thereby, as shown in FIG. 3, the automatic transmission 21 is automatically switched to the first forward speed, and when the driver steps on the accelerator, the transport vehicle 1
Starts at the first forward speed. As a result, the gear ratio becomes the largest, and a large torque is generated at the time of starting. Therefore, even when a very heavy load 2 or a large number of loads 2 are carried, there is no shortage of torque.

At this time, the traveling speed of the transport vehicle 1 is detected by the speed sensor 18, and when the traveling speed of the transport vehicle 1 reaches a predetermined speed, the control unit 74 controls the automatic transmission 21 as described in (2) above. When the speed is switched from the first speed to the second speed (see FIG. 4) and the traveling speed of the transport vehicle 1 further increases, the control unit 74 causes the automatic transmission 21 to shift the third speed and the fourth speed as described in (3) and (4) above. It switches sequentially to speed. In this case, as shown in FIG. 12A, the first to fourth speeds are respectively switched in accordance with a certain range of running speed.

When the weight of the load 2 is light or when the bed 12 is empty, the downward load acting on the bed 12 is reduced, and the hydraulic pressure detected by the hydraulic pressure sensor 17 is reduced accordingly. Therefore, when the transport vehicle 1 is started, if the oil pressure detected by the oil pressure sensor 17 becomes less than a certain value, the control unit 74 switches the automatic transmission 21 to the second speed as described in (2) above. As a result, as shown in FIG. 4, the automatic transmission 21 is automatically switched to the second forward speed, and when the driver steps on the accelerator, the transport vehicle 1 drops out of the first forward speed and the forward second speed is started from the beginning. Start fast. As a result, the reduction ratio becomes smaller than in the case of the first forward speed, and the generated torque becomes smaller than in the case of the first forward speed, but the traveling speed of the transport vehicle 1 is increased in a short time by stepping on the accelerator. Speed at the time of starting. Thereafter, when the traveling speed of the transport vehicle 1 gradually increases, the control unit 74 sequentially switches the automatic transmission 21 between the third speed and the fourth speed as described in (3) and (4) above. In this case, as shown in FIG. 12B, the second speed supplements the range of the first speed.

When the rotary knob 25 is switched to the rotation switching position corresponding to the third speed while the selector lever 23 is switched to the D range, the speed is changed only in the first to third speeds. When switching to the rotation switching position corresponding to the second speed, the speed is changed only in the first speed and the second speed, and when the rotary knob 25 is switched to the rotation switching position corresponding to the first speed, the speed is fixed to the first speed.

When the transport vehicle 1 is to travel backward,
As shown by the phantom line in FIG.
Switch 3 to R range. Thus, in response to the switching signal from the selector lever 23, the control unit 74 switches the automatic transmission 21 to the reverse mode as described in (6) above, and further, regardless of the magnitude of the hydraulic pressure detected by the hydraulic pressure sensor 17. As described in the above (1), the automatic transmission 2
Change 1 to 1st gear. Then, when the driver steps on the accelerator, the transport vehicle 1 starts at the first reverse speed.
By switching the selector lever 23 to the R range, the control unit 74 turns on the solenoid 66 of the first pilot valve 38 and switches the first pilot valve 38 to the other switching position B regardless of the traveling speed. Therefore, during reverse running, the speed is always fixed to the first speed regardless of the running speed.

In the above embodiment, the transport vehicle 1 for transporting the coil body as the load 2 has been described, but a truck or the like for transporting earth and sand may be used. In the above embodiment, as shown in FIG. 7, the oil pressure in the front lift cylinder device 13 is detected by the oil pressure sensor 17, but the oil pressure in the rear lift cylinder device 14 may be detected.

In the above-described embodiment, the hydraulic pressure sensor 17 for detecting the hydraulic pressure in the front lift cylinder device 13 is used as an example of the load detection means. However, another pressure sensor may be used. A sensor (a load cell or the like) that detects the load applied to the device may be used.

In the above embodiment, each of the lift cylinder devices 13, 14 is operated by hydraulic pressure, but may be operated by air pressure. In the above embodiment, the automatic transmission 21 automatically shifts to the first to fourth speeds, but automatically shifts to a plurality of speeds other than the first to fourth speeds (for example, first to third speeds or first to fifth speeds). The gear may be changed.

[0041]

As described above, according to the present invention, when the load detected by the load detecting means is a predetermined value or more, the transport vehicle starts with the automatic transmission in the first speed. As a result, the gear ratio is maximized, and a large torque is generated at the time of starting. Therefore, even when the load is fully loaded on the bed, there is no shortage of torque.

If the load detected by the load detecting means is less than a predetermined value, the transport vehicle starts with the automatic transmission switched to the second speed. As a result, the gear ratio becomes smaller than in the case of the first speed, and the generated torque becomes 1
Although the speed is smaller than the speed, the traveling speed of the transport vehicle can be increased in a short time by stepping on the accelerator.
Thereby, speeding up at the time of starting can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control system for automatic shifting of a transport vehicle according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of a control valve mechanism of the automatic transmission of the transport vehicle in a neutral state.

FIG. 3 is a hydraulic circuit diagram of a control valve mechanism of the automatic transmission of the transport vehicle, showing a state in which the mode is switched to a first forward speed.

FIG. 4 is a hydraulic circuit diagram of the control valve mechanism of the automatic transmission of the transport vehicle, showing a state where the transmission is switched to a second forward speed.

FIG. 5 is a diagram showing switching of D, N, and R ranges of a select lever of the transport vehicle.

FIG. 6 is a diagram of a rotary knob of a select lever of the transport vehicle.

FIG. 7 is a side view of the carrier and the lift cylinder device of the transport vehicle.

FIG. 8 is a side view of the rear body part of the transport vehicle.

FIG. 9 is a side view of the transport vehicle.

FIG. 10 is a plan view of the transport vehicle.

FIG. 11 is a rear view of the transport vehicle.

FIG. 12 is a graph showing traveling speeds of the transport vehicle corresponding to first to fourth speeds, where (a) shows a case where the vehicle starts from the first speed, and (b) shows a case where the vehicle starts from the second speed. ing.

FIG. 13 is a side view of a conventional transport vehicle.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transport vehicle 2 load 3 body 12 loading platform 13, 14 lift cylinder device 17 oil pressure sensor (load detection means) 21 automatic transmission 74 control unit

Claims (2)

[Claims] 1. A transport vehicle provided with a carrier for supporting a load and an automatic transmission on a vehicle body, wherein the load detector detects a load acting on the carrier, and the load detected by the load detector. A control unit that controls the automatic transmission based on the detected load. The control unit switches the automatic transmission to the first speed when the vehicle starts, when the detected load is equal to or greater than a predetermined value, and the detected load is A transport vehicle wherein the automatic transmission is switched to the second speed when the vehicle starts when the value is less than a predetermined value. 2. The load carrier according to claim 1, wherein the loading platform is configured to be vertically movable by a cylinder device, and a pressure sensor that detects a pressure of a working fluid in the cylinder device is used as a load detection unit. Transport vehicle.