JP2000034100A - Control device for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent no-load condition from being decided as load present condition in error by conducting designated control with priority of decision on the presence/absence of load in the condition where a detection signal for designated pressure or more is output from a pressure sensor. SOLUTION: CPU is capable of deteting three stages of a low level of no-load state, a high level of load-present state and a relief pressure level from a pressure sensor. First, the CPU reads a height, load and oscillation angle θ (S10), and if not a high level (S20), an oscillation regulating flag Fw is set to 0 (S30). When it is high level, and θ is not, -2 deg.<θ<2 deg., Fw is set. to 0. When θ is -2 deg.<θ<2 deg. and the current pressure level is high level (S20), Fw is set to 1 (S60). When the current pressure level is not high level, but relief pressure level (S90), Fw is set to 1. When Fw is 1, a lock command is output, and when Fw is 0, a lock release command is output (S110).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industry in which a cargo handling cylinder is provided, and it is determined whether or not to perform a predetermined operation based on a detection signal of a pressure sensor for detecting a working oil pressure acting on the cargo handling cylinder. It is a control device of a vehicle.

[0002]

2. Description of the Related Art Conventionally, in an industrial vehicle such as a forklift, a rear axle supporting a rear wheel is swingably mounted on a body frame in consideration of running stability and riding comfort of the vehicle. However, in a configuration in which the rear wheel axle can always swing, running stability may be reduced when turning with a load loaded or when traveling on an uneven road surface with a high altitude loaded with a load. . Therefore, when the value of the centrifugal force acting on the vehicle at high altitudes with the load loaded and the vehicle becomes a predetermined value or more,
A technique for fixing (locking) the swingably supported rear wheel axle with an axle fixing mechanism is disclosed (for example, Japanese Patent Application Laid-Open No. 58-167217, Japanese Patent Application Laid-Open No. 9-30930).
No. 8, JP-A-9-309309).

The fixing of the rear wheel axle is performed by locking a damper disposed between the body frame and the rear wheel axle. That is, by blocking (blocking) a flow path for supplying and discharging hydraulic oil to and from the damper so that the damper cannot supply and discharge hydraulic oil, the damper is locked and the rear wheel axle is fixed. Further, by setting the flow path to the communication state, the locked state of the damper is released, and the rear wheel axle is in a swingable state.

When the load is equal to or more than a predetermined value and the lift is equal to or more than a predetermined height, the lock condition may be satisfied and the rear wheel axle may be locked. Conventionally, the load is detected by detecting the operating oil pressure in the bottom chamber of the lift cylinder with a pressure sensor.

In a forklift, a mast provided with an outer mast and an inner mast provided at a front portion of a vehicle raises and lowers a fork together with a lift bracket. The mast is expanded and contracted by the operation of the lift cylinder based on the operation of the lift lever, and the fork is raised and lowered accordingly. Further, in order to facilitate the cargo handling operation and to improve the stability during traveling of the forklift, the mast is tilted forward or backward with respect to the vertical reference position by operating the tilt cylinder based on the operation of the tilt lever. .

In a forklift, when a load is loaded on the fork, the center of gravity moves forward, and when the forklift is raised, the moment acting on the mast increases. When the mast is tilted forward with a load loaded, the center of gravity moves forward, and the stability of the forklift in the front-rear direction deteriorates. In addition, if the rearward inclination angle is too large in a state where the load is large, the center of gravity may be too close to the rear side, and the front wheels may be slightly lifted and slippage may occur. Therefore, conventionally, the maximum values of the forward tilt angle and the backward tilt angle of the mast have been set to predetermined values.

[0007] When a load is placed at a high place in a cargo handling operation, it is necessary to tilt the mast forward by setting the fork to a high elevation. At this time, if the mast leans forward at a high forward leaning speed due to erroneous operation or the like, load collapse or lifting of the rear wheel of the forklift (that is, unstable state in the longitudinal direction of the vehicle) occurs. Therefore,
The operator needs to carefully perform the forward leaning operation at a low speed by inching operation so that the mast does not lean forward too much, which is a great mental burden. In addition, in the conventional apparatus, the operation of tilting the mast by setting the fork to a high elevation required skill.

[0008] The applicant of the present application, which has solved the above-mentioned disadvantages,
When performing tilting operation with high elevation and forward leaning, the work can be easily performed even by non-experts, and even if there is an erroneous operation, the tilt of industrial vehicles does not cause load collapse and lifting of the rear wheel of the forklift. A cylinder control device was proposed. In this control device, the supply of hydraulic oil to the tilt cylinder is controlled so as to regulate the forward tilt angle of the mast in accordance with the lift and the load of the cargo attachment.

[0009]

However, in the configuration in which the load is detected by the operating oil pressure of the lift cylinder, the load handling attachment is raised to the highest position while the operator operates the lift lever to the raised position, and the operating hydraulic pressure is increased. When the lift lever is returned to the neutral position with the
The pressure sensor outputs a detection signal corresponding to the relief pressure. Since the relief pressure is higher than the pressure corresponding to the maximum load, the cargo handling attachment is moved to the highest position with no load, and when the hydraulic oil reaches the relief pressure, the swing control is performed based on the lift and load. The lock condition is satisfied. On the other hand, when performing the forward tilt angle restriction control, the restriction angle corresponds to the maximum load. That is, in the unloaded state, although the rear wheel axle does not need to be locked even at high elevation, unnecessary locking of the rear wheel axle is performed, and the ride comfort and running stability during running deteriorate. In addition, the forward tilt angle cannot be tilted forward to the allowable forward tilt angle, resulting in poor workability.

The present invention has been made in view of the above problems, and a first object of the present invention is to perform a predetermined operation based on a detection signal from a pressure sensor which detects an operating oil pressure acting on a cargo handling cylinder. It is an object of the present invention to provide a control device for an industrial vehicle, which can prevent an erroneous determination of a no-load state from a no-load state in a control device for an industrial vehicle that determines whether or not to perform the operation. Further, a second object is that a rear wheel axle is swingably supported in the roll plane with respect to the body frame, and a lock means for temporarily restricting the swing of the rear wheel axle with respect to the body frame is provided. In a rear axle swing control device for an industrial vehicle, a control device for an industrial vehicle is provided which can prevent an unnecessary lock state without a load when the operating oil pressure of a lift cylinder becomes a relief pressure. Is to do.

[0011]

According to the first aspect of the present invention, there is provided a pressure sensor having a loading cylinder and detecting a working oil pressure acting on the loading cylinder. A control device for an industrial vehicle that determines whether or not to perform a predetermined operation based on a detection signal, and determines whether there is a load in a state where a detection signal of a predetermined pressure or more is output from the pressure sensor. There is provided control means for performing predetermined control by giving priority to the judgment by the load presence / absence judgment means.

According to a second aspect of the present invention, there is provided a semiconductor device comprising:
The control device is an industrial vehicle having a rear axle that is swingably supported in a roll plane with respect to a body frame, and a lock unit that temporarily regulates swing of the rear wheel axle with respect to the body frame. A swing control device for a rear wheel axle, wherein the swing control device swings the rear wheel axle when a lock condition including at least the lifting height of a cargo handling attachment and the operating oil pressure of a lift cylinder is satisfied. A detection signal of a pressure sensor that regulates movement and detects the working oil pressure,
When the detection signal from the lifting height detection means satisfies the lock condition, the control means controls the lock means when the judgment by the load presence / absence judgment means indicates that there is no load and determines that the lock condition is not satisfied.

According to a third aspect of the present invention, in the second aspect of the present invention, the lock means is disposed between the vehicle body frame and the rear wheel axle, and is adapted to swing the rear wheel axle. A damper for supplying and discharging hydraulic oil, a flow path through which the hydraulic oil supplied to and discharged from the damper flows, and an electromagnetic control provided in the middle of the flow path and controlling the supply and discharge of hydraulic oil to and from the damper And a valve.

According to a fourth aspect of the present invention, in the second or third aspect, the control means determines whether or not the operating oil pressure is a relief pressure based on an output signal of the pressure sensor. Only when the operating oil pressure is the relief pressure, the judgment by the load presence / absence judgment means is adopted as an element of the lock condition.

According to a fifth aspect of the present invention, in the invention of any one of the second to fourth aspects, the load presence / absence determining means determines that the detection signal of the lifting height detecting means does not satisfy a lock condition. The detection signal value of the pressure sensor a predetermined time before the time when the state changes from the state to the state where the lock condition is satisfied is stored in the storage means, and the detection signal of the lift detection means changes from the state where the lock condition is satisfied to the state where the lock condition is not satisfied A signal processing unit for clearing the detection signal value of the pressure sensor stored in the storage unit when the value changes.

According to the invention described in claim 6, in the invention described in any one of claims 1 to 4, the load presence / absence determining means is a sensor for detecting a load on the cargo handling attachment.

Therefore, according to the first aspect of the present invention, the control means determines whether or not to cause the actuator to be controlled to perform a predetermined operation based on the detection signal of the pressure sensor which detects the operating oil pressure acting on the cargo handling cylinder. Is determined. Then, in a state where the detection signal of the predetermined pressure or more is output from the pressure sensor, the control means performs the predetermined control of the actuator by giving priority to the determination by the load presence / absence determination means for determining the presence / absence of a load. Therefore, if the load presence / absence determining means determines that there is no load, control is performed based on the condition of no load, regardless of the magnitude of the output value of the output signal of the pressure sensor.

According to a second aspect of the present invention, in the first aspect of the invention, the control means controls a locking means for temporarily restricting the swing of the rear wheel axle with respect to the body frame, and controls the rear wheel. Functions as an axle swing control device. The control means controls the locking means so as to restrict the swing of the rear wheel axle when the cargo handling attachment has a high lift and a large load. When the detection signal of the pressure sensor that detects the operating oil pressure and the detection signal of the lifting height detection unit satisfy the lock condition, the control unit checks whether or not the determination of the load presence / absence determination unit is unloading. In this state, the lock condition is not satisfied and the lock means is controlled.

According to a third aspect of the present invention, in the second aspect of the present invention, the damper constituting the lock means supplies and discharges hydraulic oil with the swing of the rear wheel axle when the lock is not locked. Supply and discharge of hydraulic oil to and from the damper are controlled by an electromagnetic control valve.

According to a fourth aspect of the present invention, in the second or third aspect, the control means determines whether or not the operating oil pressure is a relief pressure based on an output signal of the pressure sensor. You. Then, only when the operating oil pressure is the relief pressure, the judgment of the load presence / absence judgment means is adopted as an element of the lock condition.

According to a fifth aspect of the present invention, in the invention according to any one of the second to fourth aspects, the detection signal of the lift detecting means changes from a state where the lock condition is not satisfied to a state where the lock condition is satisfied. The detection signal of the pressure sensor a predetermined time before the time when the pressure sensor changes to is stored in the storage means. Accordingly, the storage means stores a detection signal based on the load of the load before the operating oil pressure reaches the relief pressure, and stores the value if there is no load. Further, when the detection signal of the lift detecting means changes from the state where the lock condition is satisfied to the state where the lock condition is not satisfied, the detection signal value stored in the storage means is cleared. Then, based on the detection signal value stored in the storage means, it is determined whether or not there is a load in a state where the detection signal of the lifting height detection means has satisfied the lock condition.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the presence / absence of a load is determined by a detection signal of a sensor for detecting a load on the cargo handling attachment. Will be

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment of the present invention applied to a swing control device for a rear wheel axle of a forklift as an industrial vehicle to which a fork is attached as a cargo handling attachment. An embodiment will be described with reference to FIGS.

As shown in FIG. 2, a mast 3 is provided at the front of the body frame 2 of the forklift 1 in a tiltable manner. The mast 3 is composed of a pair of left and right outer masts 3a supported at the base end with respect to the body frame 2, and an inner mast 3b provided inside the mast 3 so as to be able to move up and down. On the rear side of both outer masts 3a, a lift cylinder 4 as a cargo handling cylinder is fixed in parallel with the outer mast 3a, and the tip of a piston rod 4a is attached to the inner mast 3a.
b. A lift bracket 5 is provided inside the inner mast 3b so as to be able to move up and down along the inner mast 3b, and a fork 6 as a cargo handling attachment is attached to the lift bracket 5. A chain wheel 7 is supported on the upper part of the inner mast 3b.
A chain (not shown), the second end of which is connected to the lift bracket 5, is mounted on the upper part of “a”. Then, the fork 6 is raised and lowered together with the lift bracket 5 via the chain by the expansion and contraction of the lift cylinder 4.

A base end of a tilt cylinder 8 is rotatably supported on both left and right sides of the body frame 2, and a distal end of a piston rod 8a is rotatably connected to each outer surface of the outer mast 3a. The mast 3 is tilted by the expansion and contraction of the tilt cylinder 8.

A steering 10, a lift lever 11, and a tilt lever 12 are provided at the front of the operator's cab 9, respectively. FIG. 2 shows both levers 11 and 12 in an overlapping state. The lift cylinder 4 is operated (expanded and contracted) by operating the lift lever 11, and the tilt cylinder 8 is operated (expanded and contracted) by operating the tilt lever 12.
Is to be done.

As shown in FIGS. 1 and 2, the outer mast 3a has two lift sensors 13 as lift detecting means.
14 are attached to the respective predetermined height positions. For example, limit switches are used as the lift sensors 13 and 14, and when the lift sensors 13 and 14 are engaged with a dog fixed to the inner mast 3b, the lift of the fork 6 is turned on when the lift is equal to or higher than a set value and turned off when the lift is lower than the set value. It has become. The maximum lift Hmax of the fork 6 is 5 m or 6 m. The lift sensor 13 turns off when the lift of the fork 6 is less than 2 m, and turns on when the lift of the fork 6 is less than 4 m, and the lift sensor 14 turns on when the lift of the fork 6 is less than 4 m. Therefore, the combination of the on / off of the two lift sensors 13 and 14 makes the lift of the fork 6 0 to 2 m (low lift) and 2 to 4 m.
It becomes possible to detect which of the three height ranges (middle height) and 4 m or more (high height) belongs to.

As shown in FIG. 1, a pressure sensor 15 for detecting the operating oil pressure in the lift cylinder 4 is provided at the bottom of the lift cylinder 4. The pressure sensor 15 outputs a voltage proportional to the operating oil pressure acting on the bottom chamber 4b of the lift cylinder 4. Until the operating oil pressure reaches the relief pressure, the load W is indirectly detected by the pressure sensor 15 because it is proportional to the load W of the load loaded on the fork 4.

Next, a hydraulic circuit for driving the lift cylinder 4 and the tilt cylinder 8 will be described with reference to FIG. As shown in FIG. 4, the lift cylinder 4 is connected to a lift control valve 17 via a pipe 16. A manually operated 7-port 3-position switching valve is used as the lift control valve 17. The lift control valve 17 has a, a,
The state can be switched between three states b and c. As the tilt control valve 18, a 6-port 3-position switching valve is used, and the tilt lever 12 for instructing the fork 6 to tilt and stop is used.
C, b, a corresponding to the forward leaning, neutral and backward leaning operating positions of
It is possible to switch between the three states.

A hydraulic pump 20 for supplying hydraulic oil in an oil tank 19 to each of the cylinders 4 and 8 is driven by an engine (not shown). The hydraulic pump 20 is connected to a port P1 of the lift control valve 17 via a hydraulic oil supply pipe 21 as a main pipe. The hydraulic oil supply pipe 21 is provided with a flow divider 23 for diverting hydraulic oil supplied from the hydraulic pump 20 to the cargo handling device side (lift cylinder 4 and tilt cylinder 8) and the power steering valve 22 side. I have. The hydraulic oil supply pipe 21 is connected to a return pipe 26 via a pipe 25 a provided with a relief valve 24.

The lift control valve 17 is connected to the line 16 at the port A1, to the line 25b at the port A2, and to the line 27 at the port A3. The pipe 25b is connected to the return pipe 26, and a relief valve 28 is provided on the way. The set pressure of the relief valve 24 is set to a predetermined pressure higher than the pressure corresponding to the maximum allowable load, and the set pressure of the relief valve 28 is set to a value smaller than the set pressure of the relief valve 24. The conduit 16 is connected to a bottom chamber 4b as an oil chamber on the bottom side of the lift cylinder 4.

The hydraulic pump 20 is connected to a port P11 of the tilt control valve 18 through a hydraulic oil supply pipe 29 branched from the hydraulic oil supply pipe 21. The tilt control valve 18 is connected to the line 30a at port A11 and to port A11.
At 12 they are respectively connected to the conduit 30b. The pipe 30a is connected to the rod chamber 8b of the tilt cylinder 8 by the pipe 3
Ob is connected to each of the bottom chambers 8c.

A control valve 31 and a pilot operated check valve 32 are provided in the middle of the pipe 30a. The pilot operation check valve 32 is provided between the control valve 31 and the rod chamber 8b so as to regulate the flow of hydraulic oil from the rod chamber 8b side to the control valve 31 side. The control valve 31 is a normally-closed control valve. A two-port, two-position switching valve operated by pilot oil pressure is used. The control valve 31 closes the conduit 30a by the spring force of the spring 33, and controls the conduit 30a. Communicating b
And two positions. Control valve 3
The pilot pressure to the 1 and pilot operated check valve 32 is supplied by a proportional solenoid valve 34. The control valve 31 and the proportional solenoid valve 34 constitute an electromagnetic valve that opens and closes a pipe 30 a connecting the tilt cylinder 8 and the tilt control valve 18.

The pilot pressure supply means for supplying pilot pressure to the pilot operation check valve 32 and the proportional solenoid valve 34 is provided by the flow divider 2 of the hydraulic oil supply line 21.
It is constituted by a pipe line 35 branched from the hydraulic oil supply pipe line 21 on the upstream side of 3. A pressure reducing valve 36 is provided in the middle of the pipe 35.

The proportional solenoid valve 34 has a tank port T2 connected to the return line 26a, and an A port connected to the line 3
5 is connected. In addition, B of the proportional solenoid valve 34
The port is connected to a pressure chamber (not shown) provided at one end of the spool of the control valve 31. In the control valve 31, a pressure chamber (not shown) at the other end of the spool is connected to a return pipe 26.

The proportional solenoid valve 34 is a normally closed type solenoid valve. When the solenoid is demagnetized, the B port and the tank port T2 are held in communication with each other by the action of the spring 37. . Further, the proportional solenoid valve 34 is configured so that the operation amount of the spool is proportional to the current supplied for excitation. When the solenoid is excited, the spool operates and the A port and the B port are connected. The pilot pressure set at the operating position of the spool is supplied to the spool of the control valve 31. With this pilot pressure, the spool of the control valve 31 is moved against the spring force of the spring 33.

The lift control valve 17, the tilt control valve 18, the pilot operated check valve 32, the relief valve 2
The control valves 31, 28, the control valve 31, the proportional solenoid valve 34, the pressure reducing valve 36, and the like are formed in one housing and constitute one control valve 38 as a whole.

Next, the structure of the swing control device for the rear wheel axle will be described. As shown in FIG. 3, an axle support portion 40 for supporting a rear axle 39 as a rear wheel axle is provided at a lower rear portion of the body frame 2. Rear wheels 4 on both sides
The rear axle 39 on which the steering wheel 1 is steerably supported is rotatably connected to the vehicle body frame 2 in the roll plane by the center pin 39a being rotatably supported by the axle support portion 40. The swing range of the rear axle 39 with respect to the vehicle body frame 2 is regulated by a stopper (not shown) so that the position where the rear axle 39 is parallel to the front axle is at the same angle in the clockwise and counterclockwise directions with the neutral position. ing.

As shown in FIG. 3, one hydraulic damper (hereinafter, simply referred to as "damper") 42 is provided between the body frame 2 and the rear axle 39 so as to connect the two. ing. The damper 42 is a double-acting hydraulic cylinder, and a cylinder tube 42a of the damper 42 is connected to the vehicle body frame 2 side.
The tip of a piston rod 42c extending from a piston 42b housed therein is connected to the rear axle 39 side.

The damper 42 includes a first chamber R1 and a second chamber R2 defined by a piston 42b, and a first flow path 43 and a second chamber R2.
The flow path 44 and the electromagnetic control valve 45 provided integrally with the damper 42 are connected. As shown in FIG.
When the solenoid 45a is demagnetized, a spring 4
A normally closed type 4-port 2-position switching electromagnetic direction control valve which is closed by the biasing force of 5b is used. Locking means is constituted by the damper 42 and the electromagnetic control valve 45.

When the spool (not shown) is switched to the communication position by the solenoid 45a, the electromagnetic control valve 45
The port is communicated with the port c, and the port b is communicated with the port d, so that the hydraulic oil can flow out and in between the two chambers R1 and R2 of the damper 42, and the rear axle 39
Is free to swing freely. When the spool is switched to the shut-off position, the communication between the ports is cut off, and the outflow and inflow of the hydraulic oil between the two chambers R1 and R2 is disabled, and the rear axle 39 is locked. The c port and the d port are connected to an accumulator (reservoir) 46 for storing hydraulic oil via a third flow path 47, and a third flow path 4.
7 is provided with a check valve 48.

The body frame 2 is provided with a swing angle sensor 49 as a rotational displacement sensor for detecting the swing angle θ of the rear axle 39 with respect to the body frame 2. The swing angle sensor 49 is supported on the side surface of the vehicle body frame 2 as shown in FIGS. Swing angle sensor 4
For example, a rotary potentiometer 9 is used as the reference numeral 9, and the swing of the rear axle 39 is transmitted to a swing angle sensor 49 via a link 50. Swing angle sensor 4
Reference numeral 9 outputs a detection signal indicating the swing angle of the rear axle 39. The swing angle θ is 0 ° with respect to the horizontal line of the body frame 2.
The angle is represented by the inclination angle of the rear axle 39 when, for example, and takes a value in the range of −4 ° ≦ θ ≦ 4 °.

Next, the electrical configuration of the swing control system of the forklift 1 will be described with reference to FIG. Forklift 1
51 as a control device for controlling the swinging of the robot
Includes a microcomputer 52, an A / D conversion circuit 53,
54 and an excitation / demagnetization drive circuit 55 are incorporated. The microcomputer 52 includes a CPU (central processing unit) 56 as a control unit and a signal processing unit, a ROM (read only memory) 57, a RAM (read / write memory) 58 as a storage unit, an input interface 59, and an output interface 60. It has.

The CPU 56 inputs on / off signals of the elevation sensors 13 and 14 via the input interface 59. Further, the CPU 56 controls the A / D conversion circuit 53 to execute A / D conversion.
A digital pressure signal from the pressure sensor 15 that has been D-converted and a digital output signal from the swing angle sensor 49 that has been A / D converted by the A / D conversion circuit 54 are input via the input interface 59. I do. The CPU 56 detects whether the value of the output signal from the pressure sensor 15 belongs to one of three levels of a low level corresponding to a no-load state, a high level corresponding to a no-load state, and a relief pressure level. The ROM 57 stores a map indicating the relationship between the value of the output signal from the pressure sensor 15 and the three levels of the low level, the high level, and the relief pressure level. CP
U56 indicates that the lift of the fork 6 is any of low lift (level 1), middle lift (level 2), and high lift (level 3) based on a combination of on / off signals of the lift sensors 13 and 14. Or to detect.

The CPU 56 stores an output signal from the pressure sensor 15, that is, a detection signal value in a predetermined area of the RAM 58 at predetermined time intervals. When the lift of the fork 6 changes from level 2 to level 3, the CPU 56 stores the detection signal value stored in the predetermined area at that point in another storage area for determining the presence or absence of cargo. When the lift changes from level 3 to another level, the CPU 56 clears the detection signal value stored in the load presence / absence determination storage area. The predetermined time is, for example, an interval of about several tens to hundreds of milliseconds.

The CPU 56 outputs a control signal to the excitation / demagnetization drive circuit 55 via the output interface 60,
By switching between excitation and demagnetization of the solenoid 45a,
The switching of the electromagnetic control valve 45 is controlled. Excitation and demagnetization drive circuit 55
Does not output an exciting current to the solenoid 45a when a degaussing signal (lock signal) is input from the CPU 56, but outputs a solenoid 45a when an exciting signal (unlock signal) is input.
To output the exciting current.

The ROM 57 stores a control program for executing a swing control process for limiting the expansion and contraction operation of the damper 42 and temporarily limiting the swing of the rear axle 39 with respect to the vehicle body frame 2. The CPU 56 executes the control program every several tens of milliseconds, for example. This swing control processing is performed so that the stability of the vehicle in the left-right direction does not decrease due to the position of the center of gravity of the vehicle center of gravity in the vertical direction with respect to the loading state of the load loaded on the fork 6. This is a control process for determining a lock condition based on the swing angle of the rear axle 39.

As a control program, the lock condition based on the lift and the load is satisfied in the following two cases, and the unlock condition is satisfied in the following three cases. It is remembered.

"Lock condition" (1) The lift is level 3, the swing angle is within ± 2 °, and the current pressure level is high.

(2) The lift is level 3 and the swing angle is ±
Within 2 °, current pressure level is relief pressure level and previous pressure level is high level. "Unlock condition" (1) The lift is level 1 or level 2.

(2) The current pressure level is low. (3) The current pressure level is a relief pressure level and the previous pressure level is a low level.

Here, the previous pressure level is defined as a pressure that is a predetermined time before the time when the detection signal of the lift detecting means changes from a state where the lock condition is not satisfied (level 2) to a state where the lock condition is satisfied (level 3). This is a pressure level based on the detection signal value of the sensor 15 and is determined from the detection signal value stored in the load presence / absence determination storage area. That is, it is determined based on the previous pressure level whether the pressure has reached the relief pressure when there is no load or the pressure has reached the relief pressure when there is a load. At this time, the CPU 56 functions as signal processing means as load presence / absence determination means.

The rear axle 39 is basically locked when the loading / unloading condition of a high lifting height and a large load is satisfied. However, even when the cargo loading lock condition is satisfied, the swing angle | θ | exceeds 2 ° (θ> 2 ° or θ <−2).
(°), the rear axle 39 is not locked. This is to prevent the rear axle 39 from locking when one of the rear wheels 41 rides on a step or a projection. Here, the reason that the rear axle 39 is locked in the range where the swing angle | θ |
If the swing angle θ is in the range of 2 ° or less, even if the rear axle 39 is locked, both the left and right rear wheels 41 are in contact with the road surface, and one of them does not float.

The CPU 56 sets the swing restriction flag (hereinafter, simply referred to as a flag) Fw to "1" when restricting the swing of the rear axle 39, and sets the flag Fw to "0" when the swing is not restricted. When the flag Fw is [0], the CPU 56 controls the excitation / demagnetization drive circuit 55 to supply an excitation current to the solenoid 45. On the other hand, the CPU 56
Indicates that when the flag Fw is [1], the excitation / demagnetization drive circuit 5
5 to prevent the excitation current from being supplied to the solenoid 45a.

Next, the operation of the rear wheel axle swing control device configured as described above will be described. As shown in FIG. 4, the lift cylinder 4 is connected to a lift control valve 17 through a pipe 16.
When the lift lever 11 is held at the raised position (a position) even after the fork 6 reaches the highest position,
The pressure in the bottom chamber 4b reaches the relief pressure. When the lift lever 11 is disposed at the neutral position in this state, the pressure in the bottom chamber 4b is maintained at the relief pressure. Therefore, even if there is no load on the fork 6, the pressure in the bottom chamber 4b is maintained at the relief pressure.

Next, the swing control processing will be described with reference to the flowchart shown in FIG. In the swing control process, first, C
The PU 56 reads the lift H, the load W, and the swing angle θ in step S10, and then determines in step S20 whether the lift is at level 3. If the lift is other than level 3, it is determined that the lock condition is not satisfied, and the process proceeds to step S30 to reset the flag Fw, that is, to “0”.

If the lift is level 3 in step 20, the CPU 56 proceeds to step 40 and sets the swing angle θ to -2 °.
It is determined whether it is within the range of ≦ θ ≦ 2 °. -2 ° ≦ θ
If ≦ 2 °, that is, if θ <−2 ° or θ> 2 °, the process proceeds to step 30, where the flag Fw is set to “0”.
If −2 ° ≦ θ ≦ 2 °, the process proceeds to step S50, and it is determined whether the current pressure level (current pressure level) is a high level. If the level is high, step S
Proceeding to 60, the flag Fw is set, that is, set to "1".

The CPU 56 determines in step S50
If the current pressure level is not the high level, the process proceeds to step S70, and it is determined whether the current pressure level is the relief pressure level. If it is the relief pressure level in step S70, the process proceeds to step S80, and it is determined whether or not the previous pressure level is high. If the previous pressure level is high in step S80, the process proceeds to step S60, and the flag Fw is set to "1". If the previous pressure level is not high in step S80, the previous pressure level is low, so the process proceeds to step S30, and the flag Fw is set to “0”.

If the current pressure level is not the relief pressure level in step S70, the CPU 56 proceeds to step S90 to determine whether the current pressure level is low.
If the level is low, the process proceeds to step S30, and the flag Fw is set to "0". If it is not low level in step S90,
Since the current pressure level is not any of low, high, and relief pressure, it is determined that there is an abnormality, and the process proceeds to step S100 to output an abnormality display command. An alarm device (not shown) is activated by the abnormality display command. Alarm devices include a buzzer and a display lamp.

If the flag Fw is "1" in step 110, the CPU 56 outputs a lock command and controls the excitation / demagnetization drive circuit 55 so that no excitation current is supplied to the solenoid 45a. If the flag Fw is "0", a lock release command is output, and the excitation current is supplied to the solenoid 45a by controlling the excitation / demagnetization drive circuit 55.

Therefore, when the relief pressure is at the high elevation, whether the load is present or not is determined from the previous pressure level.
The lock is not released.

This embodiment has the following effects. (1) In a state where a detection signal of a predetermined pressure or more (relief pressure) is output from the pressure sensor 15, the CPU 56 gives a higher priority to the determination by the load presence / absence determining means for determining the presence / absence of a load and performs predetermined control of the electromagnetic control valve 45. I do. Therefore, even when the pressure sensor 15 is in an output state irrelevant to the load of the load (relief pressure detection state), control suitable for a predetermined purpose can be performed.

(2) At the time of determining whether or not the lock condition based on the load and the lift is satisfied in the swing control, a detection signal corresponding to a relief pressure larger than the large load is output from the pressure sensor 15. Also, the determination of the presence or absence of a load is given priority. Therefore, it is possible to prevent unnecessary locking of the rear axle 39 without a load.

(3) A damper 42 is provided between the vehicle body frame 2 and the rear axle 39 for supplying and discharging hydraulic oil, and flow paths 43, 44 for supplying and discharging hydraulic oil to and from the damper 42. And the electromagnetic control valve 45 for controlling the supply and discharge of the working oil provided in the middle of the operation, the structure of the locking means is simple, and the switching between the locked state and the unlocked state is also simplified.

(4) The CPU 56 determines whether or not the operating oil pressure of the lift cylinder 4 is the relief pressure based on the output signal of the pressure sensor 15, and only when the operating oil pressure is the relief pressure, the load based on the previous pressure level. Since the presence / absence determination is performed, the presence / absence determination of the load is performed at the minimum necessary, and the control is simplified.

(5) The presence / absence of a load is determined by the height sensor 13,
Since the detection signal of No. 14 is changed based on the detection signal value of the pressure sensor 15 a predetermined time before the time when the lock condition of the lift is not satisfied from the lock condition is satisfied, the presence or absence of the load on the fork 6 is directly determined. There is no need to provide a new sensor for detection.

(6) If the swing angle | θ | is larger than 2 °, it is determined that one of the rear wheels 41 has climbed onto a step or a projection, and the rear axle 39 is locked even when a high lift and a large load occur. Instead, it is held in a swingable state. For this reason, traveling stability is ensured when moving to a position where the steps and protrusions disappear, and when the rear wheel 41 that has been riding on the ground contacts the road surface.

(Second Embodiment) Next, the supply of hydraulic oil to the tilt cylinder is controlled so as to regulate the forward tilt angle of the mast so as to secure a stable state in the longitudinal direction of the cargo or the vehicle at the time of the cargo handling operation. An embodiment embodied in the control device will be described with reference to FIGS. 4, 7, and 8. FIG. The same parts as those of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 8A, a tilt detection switch 61 and a tilt detection switch 62 are provided near the tilt lever 12 as tilt operation detecting means. Both detection switches 61 and 62 are micro switches, and the forward tilt detection switch 61 is turned on when the tilt lever 12 is in the forward tilt position, and is turned off when the tilt lever 12 is in any other position. The backward tilt detection switch 62 is turned on when the tilt lever 12 is in the backward tilt position, and is turned off when the tilt lever 12 is in any other position.

A knob 63 is provided above the tilt lever 12, and an operation button 64 is provided above the knob 63. The operation button 64 is used when performing automatic horizontal stop.
This is used to output an automatic horizontal stop request signal from a switch device (not shown) built in the knob 63. Then, an ON signal is output from the switch device while the operation button 64 is being pressed (pressed),
When the pressing operation is released, an off signal is output. The automatic horizontal stop refers to an operation of automatically stopping the mast 3 by rotating the mast 3 from a state in which the mast 3 is tilted forward or backward to a vertical position.

As shown in FIG. 8A, the operation button 64
Are formed in a state where the amount of protrusion from the surface of the knob 63 is small. As shown in FIG. 8B, a columnar convex portion 64a is formed at the center of the operation button 64. Convex part 64
a is formed in such a size that the entire shape can be confirmed inside the thumb.

As shown in FIG. 7, the body frame 2 is provided with a rotary potentiometer 65 as tilt angle detecting means (tilt angle sensor) for detecting the tilt angle of the mast 3. The potentiometer 65 is provided on a supporting portion that rotatably supports the base end of the tilt cylinder 8,
A rotary piece 65a for pinching a pin 66 protruding from the tilt cylinder 8 is provided. And the piston rod 8a
With the expansion and contraction of the rotary cylinder 65 together with the tilt cylinder 8
a rotates, and the potentiometer 65 outputs a detection signal corresponding to the amount of rotation of the rotating piece 65a.

Next, an electrical configuration for controlling the hydraulic circuit shown in FIG. 4 will be described. As shown in FIG. 7, a control device 67 for controlling the opening degree of the control valve 31, that is, the output pilot pressure of the proportional solenoid valve 34 includes a microcomputer 68, A
/ D conversion circuits 53 and 69 and a solenoid drive circuit 70 are provided. The microcomputer 68 includes a CPU 71
ROM 72, EEPROM 73, and RAM 74
, Input interface 75, and output interface 7
6 is provided. In this embodiment, control means for controlling the supply of hydraulic oil to the tilt cylinder 8 is configured by the tilt control valve 18, the control valve 31, the proportional solenoid valve 34, and the control device 67. The ROM 72 stores (stores) various control programs and data necessary for executing the programs. The control program includes, for example, a forward leaning angle restriction control program. Also,
The EEPROM 73 stores, as data necessary for executing the forward leaning angle restriction control program, a map representing the relationship between the lift, the load, and the maximum allowable forward leaning angle. For example, there are two types of maps, that is, a case of a high lift and a case of a low lift, and in any case where the loading load is 0, the maximum forward tilt angle corresponding to the maximum extension state of the tilt cylinder 8 is the maximum allowable forward tilt angle. θmax (for example, 6 °). on the other hand,
When there is a load, the maximum allowable forward inclination angle is different between the high lift and the low lift. In the case of a high lift, the maximum allowable forward tilt angle decreases with an increase in the load, and in the case of a low lift, the maximum allowable forward tilt angle reaches the maximum allowable forward tilt angle θmax up to a certain load. The maximum allowable lean angle decreases with increasing load. However, the maximum allowable forward tilt angle is a larger value than in the case of high elevation.

The CPU 71 is connected to the pressure sensor 15 and the potentiometer 65 via A / D conversion circuits 53 and 69 and an input interface 75, respectively. CP
U71 is the height sensor 1 via the input interface 75.
4. They are connected to the forward tilt detection switch 61 and the rear tilt detection switch 62, respectively. The CPU 71 is connected to a solenoid drive circuit 70 via an output interface 76. The CPU 71 inputs the output signals of the sensors 14 and 15, the potentiometer 65 and the switches 61 and 62, operates according to various control programs stored in the ROM 72, and operates via the solenoid drive circuit 70 when the tilt cylinder 8 is operated. A control command signal to the proportional solenoid valve 34 is output.

Next, the operation of the above-configured device will be described. When the spool is disposed at the position c by the tilting operation of the tilt lever 12, the hydraulic oil supply pipe 29 and the pipe 30b are connected, and the pipe 30a and the return pipe 26a are connected. . When the tilt lever 12 is tilted forward, the CPU 71 causes the forward tilt detection switch 61 to operate.
Is input. Then, an excitation command signal is output from the CPU 71 to the proportional solenoid valve 34 via the solenoid drive circuit 70, and pilot pressure is supplied to the control valve 31 and the pilot operation check valve 32 of the line 30a, and the operating oil is supplied to the line 30a. Can be flowed. As a result, the hydraulic oil is supplied to the bottom chamber 8c via the hydraulic oil supply pipe 29 and the pipe 30b, and the hydraulic oil in the rod chamber 8b is supplied to the oil tank 19 via the pipe 30a and the return pipe 26a. Since the discharge is performed, the tilt cylinder 8 is extended, and the mast 3 is rotated toward the front side. Mast 3
Is rotated forward (tilted) from the vertical state, the mast 3, that is, the fork 6 is tilted forward.

When the ON signal of the forward tilt detection switch 61 is input to the CPU 71, the CPU 71 executes a forward tilt angle restriction control program. In this control program, the CPU
71 is a fork 6 based on the output signal of the pressure sensor 15
Is calculated. Further, it is determined from the output signal of the lift sensor 14 whether or not the lift is high, and the maximum allowable forward tilt angle corresponding to the lift and the load is calculated from the map. Then, the CPU 71 sequentially calculates the tilt angle of the mast 3 based on the output signal of the potentiometer 65, and compares the calculation result with the maximum allowable forward tilt angle. When the difference becomes 0, the forward tilt detection switch 6
The excitation command to the proportional solenoid valve 34 is stopped even when the ON signal is output from 1. As a result, the supply of the pilot pressure to the control valve 31 and the pilot operation check valve 32 is stopped, and the flow of the hydraulic oil from the rod chamber 8b to the tilt control valve 18 is stopped. That is, even when the operator does not stop the tilting operation of the tilt lever 12 when the forward tilt angle of the mast 3 reaches the maximum allowable forward tilt angle corresponding to the load, the maximum allowable tilt angle corresponding to the load is ensured. It is held at the forward tilt angle.

If the tilt lever 12 is operated to the neutral position before the mast 3 reaches the maximum allowable forward tilt angle, the CPU
The step 71 ends the execution of the forward lean angle restriction control program.
Therefore, at this time, the mast 3 stops at a desired position of the operator at a forward inclination angle smaller than the maximum allowable forward inclination angle.

When the spool is located at the position a by the tilting operation of the tilt lever 12, the hydraulic oil supply pipe 29 and the pipe 30a are connected, and the pipe 30b and the return pipe 26a are connected. It will be in the state to be done. On the other hand, when the tilt lever 12 is tilted rearward, an ON signal of the rearward tilt detection switch 62 is input to the CPU 71. And the CPU 71
An excitation command signal is output to the proportional solenoid valve 34 via the solenoid drive circuit 70 from the control valve 3 and the control valve 3 of the line 30a.
The pilot pressure is supplied to the first and pilot operation check valves 32, and the hydraulic oil is allowed to flow through the pipeline 30a. As a result, the hydraulic oil supply line 29 and the line 30a
The working oil is supplied to the rod chamber 8b through the bottom chamber 8b.
Since the hydraulic oil in c is discharged to the oil tank 19 via the pipe 30b and the return pipe 26a, the tilt cylinder 8 is contracted, and the mast 3 is rotated rearward.

When the CPU 71 receives an ON signal from the forward tilt detecting switch 61 or the backward tilt detecting switch 62, the CPU 71 calculates an appropriate tilting speed corresponding to the loaded load and the lift, and sets the pilot pressure corresponding to the opening to the pilot pressure. Is output to the solenoid drive circuit 70 to output the excitation current supplied to the control valve 31 to the proportional solenoid valve 34. Therefore, the mast 3 is rotated forward or rearward at an appropriate tilting speed corresponding to the load and the lift.

The CPU 71 has two detection switches 61,
If no ON signal is output from any of the control signals 62, no excitation command to the proportional solenoid valve 34 is issued. Therefore,
Since pilot pressure is not supplied to the control valve 31 and the pilot operation check valve 32, the flow of hydraulic oil from the rod chamber 8b side to the tilt control valve 18 side is maintained in a blocked state.

The CPU 71 stores an output signal from the pressure sensor 15, ie, a detection signal value, in a predetermined area of the RAM 74 at predetermined time intervals, as in the above embodiment. CPU7
When the lift of the fork 6 changes from a low lift to a high lift, 1 stores the detection signal value stored in the predetermined area at that time in another load presence / absence storage area. C
When the lift changes from the high lift to the low lift, the PU 71 clears the detection signal value stored in the load presence / absence determination storage area.

When the CPU 71 calculates the load on the fork 6 based on the output signal of the pressure sensor 15,
If the output signal of the pressure sensor 15 is the relief pressure level, the load is calculated based on the detection signal value stored in the load presence / absence determination storage area.

Next, the automatic horizontal control will be described. When the tilt lever 12 is tilted forward while the operation button 64 is pressed while the fork 6 is tilted backward, the CPU
The ON signal from the operation button 64 and the forward tilt detection switch 61 is input to 71. At this time, the CPU 71 performs automatic horizontal control. When an ON signal is input from the forward tilt detection switch 61, the proportional solenoid valve 34 is excited in the same manner as described above, and the pilot check valve 32 moves from the rod chamber 8b of the tilt cylinder 8 to the tilt control valve 18. The flow is allowed. The CPU 71 inputs the output signal of the potentiometer 65 while the ON signal from the operation button 64 is input, and the tilt angle of the mast is 0 degree, that is, a value corresponding to the voltage indicating the horizontal state of the fork 6. Compare with And potentiometer 6
When the value based on the output voltage of No. 5 becomes a value indicating the horizontal state of the fork 6 (tilt angle 0 °), the CPU 71 outputs a demagnetization command to the solenoid drive circuit 70. As a result, the proportional solenoid valve 34 is switched to a position (closed position) where supply of pilot pressure to the control valve 31 and the pilot operation check valve 32 is stopped, and the operation from the rod chamber 8b side to the tilt control valve 18 side is performed. The oil flow is stopped. Then, the forward tilting operation is prevented, and even if the operator does not stop the tilting operation of the tilt lever 12, the fork 6 can be moved.
Is tilted and the mast 3 stops tilting.
Are kept horizontal.

On the other hand, when the tilt lever 12 is tilted backward while pressing the operation button 64 while the fork 6 is tilted forward, the CPU 71 receives ON signals from the operation button 64 and the rearward tilt detection switch 62. Is entered. Also at this time, the CPU 71 performs automatic horizontal control in the same manner as described above.

In order to reduce the size of the switch device built in the knob 63, the operation button 64 moves a small amount. Generally, forklift workers often work with gloves or gloves. When the operation button 64 is pressed with the work gloves or the like in performing the automatic horizontal operation, since the movement amount of the operation button 64 is small, the pressed part of the operation button 64 has a flat or constant curvature as in the conventional device. In the case of the curved surface, it is difficult to obtain the feeling of pressing, and the feeling during operation is poor. However, in this embodiment, the operation buttons 6
Since the convex portion 64a is formed at the center of 4, the convex portion 64a strongly presses a part of the inside of the thumb when the operation button 64 is pressed, and the feeling of pressing is clear.

Therefore, the following effects can be obtained in this embodiment. (7) In the state where the detection signal of the predetermined pressure or more (relief pressure) is output from the pressure sensor 15, the CPU 71 calculates the load based on the detection signal value stored in the load presence / absence storage area. Therefore, even when the pressure sensor 15 is in an output state irrelevant to the load of the load (relief pressure detection state), control suitable for a predetermined purpose can be performed.

(8) When the detection signal value of the pressure sensor 15 corresponds to the relief pressure, the current load value of the load can be obtained without providing a new load sensor. (9) Since the convex portion 64a exists at the center of the operation button 64, the operation button 64 is held in a state where the worker wears gloves or gloves.
Even if is pressed, the feeling of pressing is clear, and the feeling during operation is improved. In addition, the pressing point becomes clear due to the presence of the convex portion 64a.

The embodiment is not limited to the above, and may be embodied as follows, for example. The locking condition is not limited to that of the first embodiment, and locking is performed in a state where a load is present or a load is greater than or equal to a predetermined load at least at a predetermined lift or higher. Therefore, the swing angle is not removed from the lock condition, the lift is not divided into three stages, but is divided into two stages, ie, a high lift and a low lift. It may not be locked.

The lock condition may be added when the change rate of the lateral acceleration or the yaw rate acting on the vehicle is equal to or more than a predetermined set value, or other conditions may be added. In the first embodiment, data indicating only the presence or absence of a load is stored in the storage area for determining the presence or absence of a load, instead of storing the detection signal value of the pressure sensor as it is. For example,
“0” is stored when there is no load, and “1” is stored when there is load. Further, data indicating whether the lock condition only for the load is satisfied may be stored. For example, when determining whether or not the load locking condition is equal to or greater than a predetermined load, “0” is stored if the lock condition is less than the reference value, and “1” is stored if the lock condition is equal to or greater than the reference value. In these cases, the storage capacity required by the storage means is reduced.

A sensor for detecting the load on the fork 6 (loading attachment) may be provided as the load presence / absence determining means. For example, a sensor having a configuration in which a strain gauge or a piezo element is adhered to a fork and the presence or absence of a load is detected based on distortion generated in the fork 6 depending on the presence or absence of a load, or a non-contact type such as a photoelectric switch or an optical sensor is used. Use the sensor. In this case, the presence or absence of the load can be detected in real time.

The locking means for the rear axle 39 includes a damper 42 which is connected between the rear axle 39 and the vehicle body frame and is constituted by a double-acting hydraulic cylinder.
The present invention is not limited to the combination with the electromagnetic control valve 45 that controls the supply and discharge of the hydraulic oil to and from the damper 42, and may have another configuration.

The operation button 64 provided on the tilt lever 12 is not limited to the protrusion 64a having a columnar shape, but a substantially hemispherical shape as shown in FIG. 9A, a quadrangular prism as shown in FIG. 9B, and a triangle as shown in FIG. 9C. The shape may be a column, a truncated cone, or a truncated pyramid. Also in these cases, when the operation button 64 is pressed, the feeling (feel) becomes clear.

The position of the operation button 64 provided on the tilt lever 12 is not limited to the top of the knob 63;
As shown in (d), it may be provided on the upper front side of the knob 63. In this case, the operation button 64 is operated with the index finger, and the projection 64a (not shown) is formed in a size that can be confirmed inside the index finger.

When the present invention is applied to a tilt cylinder control device, the presence / absence or load of the load is determined based on the hydraulic oil pressure of the tilt cylinder, instead of determining the presence / absence of the load or the load of the load based on the hydraulic oil pressure of the lift cylinder. May be determined. For example, pressure sensors for detecting the hydraulic oil pressure in the rod chamber 8b and the bottom chamber 8c of the tilt cylinder 8 are provided. In addition, a map indicating the relationship between the tilt angle and the load and the detection signal of the pressure sensor is stored in a storage unit (for example, an EEPROM). Then, the load of the load is determined based on the detection signals of the two pressure sensors, the detection signal of the potentiometer (tilt angle sensor) 65, and the on / off signals of the front tilt detection switch 61 and the rear tilt detection switch 62. Further, when the pressure becomes the relief pressure, the predetermined control is performed based on the load before the predetermined time before the pressure becomes the relief pressure.

The operation button 64 is not limited to the automatic horizontal stop, and may be used as a switch for instructing other controls. The present invention may be applied to a forklift having a configuration in which an electromagnetic proportional control valve is used for controlling the tilt cylinder 8 without using the manually operated lift control valve 18.

The height sensors 13 and 14 may be sensors that can detect whether or not there is a detected portion, and a proximity switch or an optical switch may be used instead of the limit switch.

Attachment other than the fork 6 as a cargo handling attachment, for example, a roll clamp used for transporting roll paper, a block clamp used for transporting blocks or stacking work, or a coiled wire or cable such as a coil. Alternatively, the present invention may be applied to an industrial vehicle equipped with a ram or the like used for transporting a cylindrical load.

The present invention may be applied to a reach type forklift. The present invention is not limited to an industrial vehicle driven by an engine, and may be applied to an industrial vehicle driven by a battery.

The technical ideas (inventions) other than those described in the claims that can be understood from the above embodiments will be described below together with their effects. (1) In the invention according to claim 5, the signal processing means stores a detection signal value of the pressure sensor in a predetermined area of a storage means at predetermined time intervals, and the detection signal of the lifting height detection means does not satisfy a lock condition. When the state changes from the state described above to the state where the lock condition is satisfied, the detection signal value stored in the predetermined area is stored in another storage area for determining the presence or absence of a load in the storage means. In this case, the configuration for storing the detection signal value of the pressure sensor a predetermined time before the time when the detection signal of the lift detecting means changes from the state in which the lock condition is not satisfied to the state in which the lock condition is satisfied is simplified. .

(2) In the invention according to claim 5 or (1), the signal processing means changes the detection signal value of the pressure sensor into data indicating only the presence or absence of a load and stores the data in the storage means. In this case, the capacity required for the storage means is reduced.

(3) In the invention described in (5) or (1), the signal processing means is a data indicating whether or not a detection signal value of the pressure sensor is less than a reference value which is a reference for determining a lock condition by load. And store it in the storage means. In this case, the capacity required for the storage means is reduced.

(4) An operation button of a switch device provided on a knob of an operation lever of an industrial vehicle, wherein the operation button is provided with a convex portion having a size identifiable on the inner surface of a finger at the center of the operation button. The operation button of the switch device for the operation lever of the vehicle. In this case, even if the operator presses the operation button while wearing gloves or gloves, the feeling of pressing the operation button becomes clear, and the feeling during operation is improved.

(5) In the invention described in (4), the operation lever is a tilt lever of a forklift, and the switch device is a switch for an automatic horizontal stop command. In this case, the operability (feeling) when instructing the automatic horizontal stop is improved.

[0104]

As described in detail above, claims 1 to 6 are provided.
According to the invention described in (1), control suitable for a predetermined purpose can be performed even in an output state in which the pressure sensor is unrelated to the load of the load.

According to the second aspect of the present invention, when the rocking control determines whether or not the lock condition based on the load and the lift is satisfied, the pressure sensor corresponds to a relief pressure larger than the large load. Even if the detection signal is output, the determination of the presence or absence of the load is prioritized, so that unnecessary locking of the rear wheel axle can be avoided in a state where there is no load.

According to the third aspect of the present invention, the configuration of the locking means is simple, and the switching between the locked state and the unlocked state is also simplified. According to the fourth aspect of the present invention, only when the operating oil pressure is the relief pressure, the presence / absence of a load is determined based on the previous pressure level. become.

According to the fifth aspect of the present invention, the presence / absence of a load on the loading / unloading attachment is determined because the presence / absence of a load is determined based on the detection signal value of the pressure sensor stored in the storage means under predetermined conditions. It is not necessary to newly provide a sensor for directly detecting the state.

According to the sixth aspect of the present invention, the presence or absence of a load can be easily determined by the detection signal of the sensor.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a rear wheel axle swing control device according to a first embodiment.

FIG. 2 is a side view of a forklift.

FIG. 3 is a schematic rear view of a vehicle body and a rear axle.

FIG. 4 is a hydraulic circuit diagram for operating a lift cylinder and a tilt cylinder.

FIG. 5 is a block diagram showing an electrical configuration of a rear wheel axle swing control device.

FIG. 6 is a flowchart of a swing control process.

FIG. 7 is a block diagram illustrating an electrical configuration of a control device according to a second embodiment.

8A is a side view of a tilt lever, and FIG. 8B is a partial schematic perspective view of a knob.

9A to 9C are partial schematic perspective views of a knob according to another embodiment, and FIG. 9D is a partial side view of a tilt lever according to another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift as an industrial vehicle, 2 ... Body frame, 3 ... Mast, 4 ... Lift cylinder as cargo handling cylinder, 6 ... Fork as cargo handling attachment,
8. Tilt cylinder as cargo handling cylinder, 13,
14: Height sensor as height detecting means, 15: Pressure sensor, 34: Proportional solenoid valve as actuator, 39: Rear axle as rear wheel axle, 42: Dampers constituting locking means, 43, 44 ... Road, 4
5 ... Electromagnetic control valves as actuators constituting lock means, 56, 71 ... CPUs constituting signal presence / absence determination means and signal processing means and control means, 58, 7
4: RA as storage means constituting load presence / absence determination means
M.

Claims (6)

[Claims] 1. A cargo handling cylinder is provided, and it is determined whether or not an actuator to be controlled performs a predetermined operation based on a detection signal of a pressure sensor that detects a working oil pressure acting on the cargo handling cylinder. A control device for an industrial vehicle, wherein in a state where a detection signal of a predetermined pressure or more is output from the pressure sensor, a control unit that performs predetermined control by giving priority to a determination of a load presence / absence determination unit that determines presence / absence of a load. Industrial vehicle control device equipped with. 2. The control device according to claim 1, wherein the rear wheel axle is supported on the body frame such that the rear wheel axle can swing in a roll plane, and a lock unit for temporarily restricting the swing of the rear wheel axle with respect to the body frame is provided. A swing control device for a rear axle of an industrial vehicle, the swing control device comprising: a lock controller that includes at least a lift of a cargo handling attachment and an operating oil pressure of a lift cylinder as a lock condition. When the detection signal of the pressure sensor for controlling the swing of the rear wheel axle and detecting the working oil pressure and the detection signal of the lift detecting means satisfy the lock condition, the judgment of the load presence / absence judgment means that there is no load. The control device for an industrial vehicle, further comprising a control unit that controls the lock unit if the lock condition is not satisfied when the state of (1) is satisfied. 3. A damper disposed between the vehicle body frame and the rear wheel axle and for supplying and discharging hydraulic oil with the swing of the rear wheel axle. The industrial vehicle control according to claim 2, further comprising: a flow path through which the supplied and discharged hydraulic oil flows; and an electromagnetic control valve provided in the middle of the flow path and configured to control the supply and discharge of the hydraulic oil to and from the damper. apparatus. 4. The control means determines whether or not the operating oil pressure is a relief pressure based on an output signal of the pressure sensor, and locks the determination of the load presence / absence determining means only when the operating oil pressure is a relief pressure. The industrial vehicle control device according to claim 2 or 3, wherein the control device is employed as a condition element. 5. The load presence / absence determination means stores a detection signal value of the pressure sensor a predetermined time before a time point when the detection signal of the lift detection means changes from a state where the lock condition is not satisfied to a state where the lock condition is satisfied. And a signal processing means for clearing the detection signal value of the pressure sensor stored in the storage means when the detection signal of the lift detection means changes from the state where the lock condition is satisfied to the state where the lock condition is not satisfied. The control device for an industrial vehicle according to any one of claims 2 to 4. 6. The load presence / absence determining means is a sensor for detecting a load on a cargo handling attachment.
The control device for an industrial vehicle according to any one of the preceding claims.