JPS6226133A - Device for controlling switch-back traveling of cargo vehicle having automatic transmission - Google Patents

Abstract

PURPOSE:To make switchback control of a vehicle while securing the safety of a cargo regardless of the skill of a driver by providing a control means for controlling an indexing means so as to make a brake driving means get an indexed negative acceleration. CONSTITUTION:A microcomputer 21 as an index means as well as a shifting means consists of a CPU 22, a program memory 23 consisting of a memory ROM which stores a control program, and a working memory 24 consisting of a readable and rewritable memory RAM which temporarily stores operated results, etc. When the CPU 22 judged that a forwarding/backing operating lever 15 is shifted to a neutral position during traveling, it makes driving control of a clutch controlling actuator 9 and a forwarding/backing shifting actuator 11 in accordance with a previously determined program for carrying out a switchback traveling, an inertial traveling, or a traveling for inertial traveling, based on the judged results.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a switchback travel control device for a vehicle equipped with an automatic transmission, particularly for a cargo handling vehicle such as a forklift.

(Prior Art) In recent years, various vehicles equipped with automatic transmissions have been proposed, and cargo handling vehicles such as forklifts equipped with automatic transmissions have also been proposed. On the other hand, in cargo handling vehicles such as forklifts, it is necessary to frequently switch between forward and reverse travel during cargo handling operations, so when switching the direction of travel from forward to reverse or from reverse to forward, the driver must , Switchback involves operating the forward/reverse control lever to change the direction point from forward to reverse or from reverse to forward while the vehicle has decelerated to a certain degree before the vehicle comes to a secure stop, and at the same time, connects the clutch. I was running.

(Problem to be Solved by the Invention) Since the weight 1 of the load loaded on a vehicle during cargo handling work is not constant, the amount of deceleration of the vehicle during the switchback operation and the timing of switching the forward/reverse operation lever depend on the weight of the load. It is necessary to change it accordingly.

However, conventionally, the amount of deceleration and the timing of switching the forward/reverse operation lever have been determined by the driver's long experience and intuition. Therefore, there are inconveniences such as damage to the transmission due to forced switchback driving in a vehicle speed state where forward/reverse switching is not possible, or movement of cargo due to sudden deceleration.

Structure of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention includes a load detector that detects the shape of the cargo, and a forward/reverse operation lever that is operated while the vehicle is traveling. A memory in which the relationship between negative acceleration and load suitable for performing switchback driving in which the direction point 1- corresponding to the current driving direction is switched to the direction point in the opposite driving direction is stored as data. a vehicle speed detector that detects the running speed of the vehicle; a brake drive means that adjusts the braking state of the brake; and switchback driving based on the load detected by the load detector and data stored in the storage device. an indexing means for determining a negative acceleration suitable for the vehicle, a control means for controlling the brake driving means so that the negative acceleration determined by the indexing means is achieved, and a speed at which the traveling speed of the vehicle is determined in advance. A clutch driving means and a transmission are configured to switch the automatic transmission from a gear engagement corresponding to the current running direction to a gear engagement in the opposite direction to the current running direction when the speed is decelerated, and to connect the clutch when the switching is completed. A configuration is adopted in which a switching control means for operating the drive means is provided.

(Function) In the present invention, when performing switchback travel, the brake drive means is driven to automatically apply the brakes so that a suitable negative acceleration corresponding to the load detected by the load detector is obtained. When the traveling speed of the vehicle is decelerated to a predetermined speed, the switching control means switches the automatic transmission from a gear engagement corresponding to the current traveling direction to a gear engagement in the opposite direction to the current traveling direction, and the switching is performed. When completed, the clutch drive means and transmission drive means are operated to connect the clutch.

(Example) Hereinafter, an example in which the present invention is embodied in a forklift will be described with reference to the drawings.

Figure 1 shows the mechanism of the drive system of a forklift, in which the output of the engine 1 is transmitted through a dry single-plate clutch 2 to an automatic transmission 3.
The automatic transmission 3 drives the running drive wheels 5 forward and backward at a predetermined gear ratio via the differential gear mechanism 4. or,
The engine 1 is also used as a drive source for a hydraulic pump that supplies hydraulic oil to a lift cylinder 7 for raising and lowering the fork 6 and a tilt cylinder 8 for tilting a mast (not shown).

The dry single-plate clutch 2 that cuts the output of the engine 1 has its connected state adjusted in accordance with the stroke amount of a rod 9a that expands and contracts based on the drive of a clutch control actuator 9 as a clutch drive means. Ru. On the other hand, the automatic transmission 3 can be shifted between 1st speed (low speed) and 2nd speed (higher speed) by driving the shift switching actuator 10, and the forward/reverse switching actuator 11
It is possible to switch between forward travel, neutral (neutral), and reverse travel by driving the vehicle.

Next, an electric circuit for driving and controlling each of the actuators 9 to 11 will be explained with reference to FIG. 2.

The vehicle speed sensor 12 detects the rotational speed of the output shaft of the automatic transmission 3, as shown in FIG. 1, and outputs the detection signal to the input/output interface 13. The forward/reverse motion detection sensor 14 detects the switching state (forward, neutral, reverse) of a forward/reverse motion control lever 15 provided at the driver's seat, that is, the direction point, and outputs the detection signal to the interface 13 .

The load detection sensor 16, which serves as a load detector for detecting the weight of the cargo, is composed of a pressure sensor, and detects the hydraulic pressure of the hydraulic oil in the lift cylinder 7, that is, the weight of the cargo 17 applied to the fork 6, and its detection signal is A/ The signal is converted into a digital signal by the D converter 18 and output to the interface 13.

The backward tilt angle of the fork 6 is detected from the stroke amount of the tilt cylinder 8, and the stroke detection sensor 19 that detects the stroke is composed of a potentiometer.
The detection signal is converted into a digital signal by the A/D converter 20 and output to the interface 13.

A microcomputer 21 serving as an indexing means and a switching control means is a central processing unit (hereinafter referred to as CPU) 22.
and a read-only memory (RO) that stores the control program.
A readable and rewritable memory (RAM) that temporarily stores arithmetic processing results, etc.
), and the CPU 22 operates based on program data stored in the program memory 23.

In addition to the control program, the program memory 23 stores negative acceleration suitable for switchback driving;
The relationship between the weight of the cargo, that is, the load, is stored in advance as data.

The CPU 22 inputs detection signals from each of the sensors via the input/output interface 13.

The CPU'U 22 sequentially calculates the running speed and acceleration of the forklift at that time based on the detection signal from the vehicle speed sensor 12, and stores the calculation results in the working memory 24.
to be memorized. Further, the CPU 22 detects the forward and backward motion detection sensor 1.
Based on the detection signal from 4, the direction point of the forward/reverse operation lever 15 at that time is determined.

Furthermore, the CPU 22 calculates the weight of the cargo at that time, that is, the load, based on the detector number from the load detection sensor 16, and stores the calculation result in the working memory 24.

Further, the CPU 22 calculates the backward inclination angle of the fork based on the detection signal from the stroke detection sensor 19, and stores it in the working memory 24.

Note that each calculation and judgment performed by the CPU 22 on these detection signals is performed based on data stored in the program memory 23 in advance.

Further, the CPU 22 controls the clutch control actuator 9, the forward/reverse switching actuator 11, and the brake actuator via the input/output interface 13 and each actuator drive circuit 25, 26, 27, 28 based on predetermined program data. 29 and a control valve drive device 30 for the tilt cylinder 8.

When the CPU 22 determines that the forward/reverse operating lever 15 has not been switched to neutral during driving, the CPU 22 performs a driving determination processing operation, that is, determines whether the neutral operation of the forward/reverse operating lever 15 performed by the driver is switchback driving, coasting shift driving, or coasting. It is designed to perform a processing operation to determine whether the operation is for driving. And CPU2
2 drives and controls the clutch control actuator 9 and the forward/reverse switching actuator 11 according to a predetermined program to perform switchback driving, coasting shift driving, or coasting driving based on the determination result. It has become.

In addition, when the CPU 22 determines to perform switchback travel, the CPU 22 adjusts the forklift to the negative acceleration according to the @m of the load 17 based on the relationship between the load and the optimal negative acceleration shown in FIG. The brake 31 is controlled to operate. Furthermore, if the fork 6 is not in a completely backward tilted state, the fork 6
control so that it is completely tilted backwards.

Next, the operation of the electric block circuit configured as described above will be explained according to the flowcharts shown in FIGS. 4 and 5.

Now, when the driver switches the forward/reverse operation lever 15 from forward to neutral while the forklift is moving forward at a predetermined speed, the CPU 22 will set the direction point to neutral based on the detection signal from the forward/reverse detection sensor 14. Step s to determine that it has been switched to
1) Drive-control the clutch control actuator 9 via the interface 13 and the actuator drive circuit 25 to disengage the dry single-plate clutch 2 at the maximum speed (step S2>. At the same time, the CPU 22 is installed in the CPU 22). The timer is activated to determine whether the forward/reverse operating lever 15 has not been switched to a direction point other than neutral within a predetermined time (hereinafter referred to as set time t, 1 second in this embodiment) (step 83.8).
4).

Even if the set time t has elapsed, the forward/reverse operation lever 15
is not operated and the direction point does not change, the CPU 22 executes coasting control processing operation to cause the forklift to coast (step 85).
. That is, the CPU 22 determines that coasting is occurring in response to the time-up, drives and controls the forward/reverse switching actuator 11 to change the gear of the automatic transmission 1113 from forward to neutral, and then connects the disconnected dry single-plate clutch 2. do. Therefore, the forklift will coast in this state.

On the other hand, when the forward/reverse operation lever 15 is switched to forward again within the set time, the CPU 22 determines that it is a coasting shift (step S6), and executes a coasting shift control processing operation to cause the forklift to travel forward again (step S6).
Step 87). That is, the CPU 22 simply connects the dry single plate clutch 2 in response to the fact that the direction point is not switched to forward again. Therefore, the forklift will continue moving forward again. Further, when the operating lever 15 is not switched to reverse within the set time, the CPU 22 determines that switchback travel is to be performed (step S6), and executes a switchback control processing operation to cause the forklift to switchback travel (step S6). S8).

When switchback driving control starts, CPtJ22
determines whether there is a cargo based on the detection signal from the load detection sensor 16 (step S9). Then, if there is cargo, calculate the weight of the cargo (step 510).
, calculates a suitable negative acceleration corresponding to the load based on data stored in advance in the program memory 23 (step $11). Then, the brake actuator 29 is controlled via the input/output interface 13 and the actuator drive circuit 27 to obtain the negative acceleration (step 512), and the forklift is decelerated. At this time, the CPU 22 controls the vehicle speed sensor 12.
The vehicle speed is calculated based on the detection signal from the vehicle speed, and the negative acceleration is calculated based on the change in the vehicle speed, and it is determined by successive comparison whether the forklift is being decelerated by a predetermined negative acceleration.

Further, when there is a load 17 on the fork 6, the CPU 22 determines whether the fork 6 is fully tilted backward based on the detection signal of the stroke detection sensor 19 (step 513). Then, if the fork 6 is not in a completely backward tilted state, an increment in rearward tilt is calculated to make the fork 6 fully backward tilted (step 514), and the control valve drive device 30
is controlled to drive the tilt cylinder 8 by an amount corresponding to the rearward tilt increment (step 515).

When the speed, which is sequentially calculated based on the detection signal from the vehicle speed sensor 12, becomes lower than a predetermined speed at which the gear can be changed from forward to reverse, the CPU 22 activates the actuator drive circuit 26.
The forward/reverse switching actuator 11 is drive-controlled via the forward/reverse switching actuator 11 to switch the gear of the automatic transmission 3 from forward to reverse (step 816).

When the gear of automatic transmission 3 is switched from forward to reverse (
Step 816), control is performed to reverse the traveling direction of the forklift (step 517). That is, the clutch 2 is connected to further decelerate the forklift, and the brake actuator 29 is driven in a direction to release the brake 31. Immediately after the forklift decelerates and stops, it reverses its traveling direction and begins traveling backwards (step 517).

Then, after the reversal of the traveling direction is completed, the tilt cylinder 8 is operated via the control valve drive device 30 so that the backward tilt angle of the fork is in the initial state (step 818
).

On the other hand, if there is no cargo when starting switchback travel, the brake actuator 29 is drive-controlled to a state where the maximum negative acceleration is obtained, and the brake 31 is activated (step $19). Then, step S19
After step 316 is executed, each operation after step 316 is executed in the same manner as described above.

In this case, although the description has been made regarding traveling from forward to reverse, switchback travel from reverse to forward is also performed by the same processing operation.

As described above, in the present invention, the brakes are automatically applied in response to lff1 of the cargo 17 to obtain negative acceleration during switchback travel, and the vehicle is decelerated to a predetermined speed that allows forward and forward switching. Since the gears are automatically switched and the clutch is connected, ideal deceleration is always possible regardless of the skill of the driver, the presence or absence of cargo, and changes in weight. There is no risk of damage to the automatic transmission.

In addition, in the device of this embodiment, the fork is tilted completely backward before the direction of travel is reversed from forward to reverse or from reverse to forward during switchback travel, so the forklift does not reverse its direction of travel. This reliably prevents the inconvenience of the cargo moving due to inertia when the cargo is moved.

Note that the present invention is not limited to the embodiments described above, and for example, the drive amount of the brake 31 and the negative acceleration are calculated in accordance with the load, without constantly calculating the negative acceleration based on the detection signal from the vehicle speed sensor The relationship between the acceleration of Alternatively, steps 313 to 815 and step 818 may be omitted. Furthermore, although the above embodiment was applied to a forklift, it goes without saying that the invention may also be applied to a cargo handling vehicle such as a shovel loader.

Effects of the Invention As detailed above, according to the present invention, when a cargo handling vehicle equipped with an automatic transmission is running switchback, one of the loads is
Since the speed is automatically reduced to a speed that allows forward/reverse gear changes under appropriate R conditions, switchback control can be performed while ensuring the safety of the cargo regardless of the driver's skill. Moreover, it has an excellent effect in that there is no risk of damaging the transmission or the like.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram showing the drive system mechanism of forklifts 1 to 1 embodying the present invention, Fig. 2 is an electric block circuit diagram of the forklift, and Fig. 3 is a load and load diagram. 4 and 5 are flowcharts for explaining the action. In the figure, 1 is the engine, 2 is the dry single plate clutch, 3 is the automatic transmission, 6 is the fork, 7 is the cylinder 71, 8 is the cylinder 1, and 9 is the clutch control actuator.
11 is a forward/reverse switching actuator, 12 is a vehicle speed sensor, 15 is a forward/backward operating lever, 16 is a load detection sensor, 1
9 is a stroke detection sensor, 21 is a microcomputer, 22 is a central processing unit (CPU), 23 is a program memory, 24 is a working memory, and 31 is a brake. Patent applicant: Toyota Industries Corporation Fujitsu
Co., Ltd.

Claims (1)

[Claims] 1. A load detector that detects the weight of the cargo, and a direction point in the opposite direction of travel from a direction point that corresponds to the current travel direction by operating the forward/reverse control lever while the vehicle is traveling. A storage device that stores data on the relationship between negative acceleration and load suitable for switchback driving, a vehicle speed detector that detects the vehicle's running speed, and a vehicle speed detector that detects the braking state of the brake. a brake drive means for adjusting; an indexing means for determining a negative acceleration suitable for switchback driving based on the load detected by the load detector and data stored in the storage device; control means for controlling the brake driving means so as to achieve a negative acceleration of the vehicle; A cargo handling vehicle equipped with an automatic transmission equipped with a switching control means that operates a clutch driving means and a transmission driving means so as to switch gear engagement in a direction opposite to the traveling direction and connect a clutch when the switching is completed. Switchback travel control device.