JP2002178947A - Steering control device for wheel type working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhibit higher steering performance by means of a simple arrangement by increasing degrees of freedom of operation while maintaining safety during normal travel. SOLUTION: This steering control device includes a mode change control means 21 and a lock actuation control means 22 and a steering mode is automatically changed according to the steering mode selected by use of a mode selecting switch 17. When a normal mode is selected while an output changing switch 19 is off, the change to the normal mode is permitted for steering front wheels while retaining rear wheels only if a neutral position detecting switch 14 detects that the rear wheels are in neutral positions. When the normal mode is selected while the switch 19 is on, the mode is immediately changed to the normal mode, after which the front wheels are made steerable while the steering angle of the rear wheels is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering control device for a wheel type working machine such as a wheel crane which can be switched between a normal mode in which only front wheels are steered and a rear wheel steering mode in which at least rear wheels are steered. Things.

[0002]

2. Description of the Related Art Conventional wheel-type working machines include not only a normal mode in which only the front wheels are steered as in a normal car, but also at least a small turning at a work site to improve running in narrow places. In some cases, a rear wheel steering mode in which the rear wheels can be steered is provided. The rear wheel steering mode includes a so-called club mode in which front and rear wheels are steered in the same direction, a so-called clamp mode in which front and rear wheels are steered in opposite directions, and a rear steering mode in which only the rear wheels are steered. Have been. In addition, when the work machine travels on a public road, a normal mode is used for safety, and a mode such as using a rear wheel steering mode is used during work, and in the normal mode,
In order to prevent the rear wheel from floating and meandering, an operation is performed in which the rear wheel is inoperatively locked by a lock pin while the rear wheel is in the neutral position.

Conventionally, an apparatus disclosed in Japanese Utility Model Publication No. Sho 62-5975 is known as an apparatus for performing such switching control of the steering mode. This device includes a mode selection switch for selecting a steering mode, and operates a lock pin in conjunction with operation of the switch. Specifically, a normal mode is selected by a mode selection switch. When the rear wheel steering mode is selected, the lock is automatically released when the rear wheel steering mode is selected.

Further, this device also detects whether or not the rear wheel is at a neutral position, and automatically sets the rear wheel to the neutral position when the normal mode is selected even though the rear wheel is not at the neutral position. The lock is performed after the correction, and the normal mode is set.

However, in such a device for performing automatic correction to the neutral position, regardless of the driver's operation of the steering wheel, in other words, regardless of the driver's intention,
Since the rear wheels are automatically operated, the relationship between the operation contents of the steering wheel and the actual rear wheel position is disengaged when correcting the rear wheels, which may disturb the driver's senses and hinder subsequent driving. is there.

Therefore, Japanese Utility Model Publication No. Hei 8-5902 discloses that
When the rear wheel steering mode is selected, the rear wheel lock is automatically released and the steering mode is switched to the selected mode.On the other hand, when the normal mode is selected, switching to the normal mode is prohibited until the rear wheels are in the neutral position. It is disclosed that the mode is switched to the normal mode only when the neutral position of the wheel is detected.

[0007]

SUMMARY OF THE INVENTION
In the device disclosed in Japanese Patent Laid-Open Publication No. 2 (1993) -1995, switching to the normal mode is allowed only when the rear wheel is in the neutral position, so that the driver switches to the normal mode while inadvertently forgetting to return the rear wheel to the neutral position. While preventing the situation of being steered (that is, ensuring high safety during normal driving), the front wheel steering in the normal mode is limited to the state where the rear wheel is in the neutral position, so the front wheel steering angle and the rear wheel steering There is a situation that the angle cannot be set independently. Therefore, the vehicle cannot be driven with the center of rotation of the vehicle set at an arbitrary position, and sufficient steering performance cannot be exhibited.

Incidentally, Utility Model Registration Publication No. 2580272
No. 6,019,837 discloses a hydraulic system in which the front and rear wheels can be simultaneously and independently steered, but such a system is compared with a conventional system (for example, a hydraulic system disclosed in Japanese Utility Model Publication No. Hei 8-5902). The configuration becomes extremely complicated, and a significant increase in cost is unavoidable. In addition, since there is no limitation due to the steering mode and it depends on the driver's feeling, it is difficult to secure the above-mentioned safety.

In view of such circumstances, the present invention provides a steering control device which has a simple structure and which can enhance the degree of freedom of driving and exhibit higher steering performance while maintaining safety during normal driving. The purpose is to do.

[0010]

According to the present invention, a steering mode includes a normal mode in which only front wheels are steered in conjunction with an operation of a steering operation member while a rear wheel steering angle is kept constant, and At least one of a mode in which at least the rear wheel is steered in conjunction with the operation of the member and only the rear wheel is steered, or a mode in which the front and rear wheels are steered while maintaining a constant relationship between the front and rear wheels In a steering control device for a wheel-type work machine including a mode switching means for switching to a rear wheel steering mode, a mode selection means for selecting the steering mode, and detecting whether or not the rear wheel is at a neutral position. Rear wheel neutral position detecting means, a changeover switch provided separately from the mode selecting means, and rear wheel steering by the mode selecting means. When the mode is selected, the steering mode is switched to the selected mode. When the changeover switch is off and the normal mode is selected by the mode selection means, the rear wheel neutral position detection is performed. Means for maintaining the steering mode in the current mode until the rear wheels are in the neutral position, and switching the steering mode to the normal mode when the rear wheels are detected in the neutral position; When the switch is on and the normal mode is selected by the mode selecting means, the mode switching control means for immediately switching the steering mode to the normal mode regardless of whether the rear wheels are in the neutral position. It is provided.

According to the above configuration, when the rear wheel steering mode is selected, the steering mode is directly switched to the selected mode.

On the other hand, when the changeover switch is off and the normal mode is selected, the mode is not switched until the rear wheel comes to the neutral position, and the rear wheel is actually returned to the neutral position by the steering operation member. Then, the steering mode is switched to the normal mode only when the normal mode is selected by the mode selection means. Therefore,
For example, by turning off the changeover switch during normal running, it is possible to prevent the driver from inadvertently switching to the normal mode without forgetting to return the rear wheel to the neutral position, and to ensure high safety. Can be.

On the other hand, when the changeover switch is on and the normal mode is selected, the steering mode is immediately switched to the normal mode regardless of the actual rear wheel steering angle, and the rear wheel steering angle at that time is changed. Is performed while the front wheel is steered. Therefore, the driver can freely set the relative relationship between the front wheel steering angle and the rear wheel steering angle to perform wide driving by appropriately switching the steering mode while the changeover switch is turned on. For example, it is possible to more easily cope with work in a narrow place.

The holding of the rear wheel steering angle in the normal mode may be performed, for example, only by blocking the steering hydraulic circuit. However, a rear wheel locking means for locking the rear wheel at a neutral position, a steering mode Is switched to the normal mode, and lock switching control means for locking the rear wheel locking means when the rear wheel neutral position detecting means detects that the rear wheel is in the neutral position, If the rear wheels are mechanically locked at the neutral position, normal driving with higher safety can be realized.

In the present invention, the location of the changeover switch is not particularly limited. If the switch is provided on the steering operation member, the driver can turn on and off the changeover switch while operating the steering operation member. Switching can be performed, and operability is further improved.

Further, the vehicle is provided with vehicle speed detecting means for detecting the vehicle speed of the work machine. When the vehicle speed detected by the vehicle speed detecting device is equal to or higher than a predetermined value, the rear wheel is not at the neutral position regardless of whether the switch is on or off. If the mode switching control means is configured to prohibit switching to the normal mode in the state, even if the driver does not turn off the changeover switch, the high speed by the normal mode when the rear wheel is not in the neutral position is provided. Driving is automatically blocked, ensuring higher safety.

Further, when the vehicle speed detected by the vehicle speed detecting means is equal to or higher than a predetermined value, the mode switching control means is configured to maintain the current steering mode regardless of the mode selection by the mode selecting means. Good.

According to the present invention, since it is possible to switch to the normal mode when the rear wheels are not in the neutral position, both the front wheels and the rear wheels are simultaneously operated as the rear wheel steering mode while maintaining a fixed relationship. When the steered mode is included, in this mode, the timing at which the front wheels return to the neutral position and the timing at which the rear wheels return to the neutral position may deviate. Therefore, a front wheel neutral position detecting means for detecting whether or not the front wheel is at a neutral position, and a timing at which the front wheel returns to the neutral position in a mode in which the front and rear wheels are simultaneously steered while maintaining a fixed relationship, and Warning means for giving a warning when any of the timings of returning to the normal state is provided, and by notifying the driver of the occurrence of the timing deviation, it is possible to prevent driving from being continued while erroneously recognizing the current steering state. And higher security can be ensured.

[0019]

FIG. 1 shows the overall configuration of a steering control device according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a pair of front wheel steering cylinders for steering left and right front wheels, and reference numeral 2 denotes a rear wheel steering cylinder for steering left and right rear wheels. The hydraulic pump 5 and the tank 6 are connected via a mode switching means) and a steering unit having a steering wheel (steering operation member) 4.

The mode switching valve 3 includes a plurality of hydraulic electromagnetic switching valves for controlling the supply and discharge of hydraulic oil to and from the steering cylinders 1 and 2. By switching the mode switching valve 3, the actual steering mode is switched to the normal mode. The mode can be switched to one of a club mode, a clamp mode, and a rear steering mode. The contents of each mode are as follows.

1) Normal mode: Only the front wheels are steered in conjunction with the operation of the steering wheel 4. The rear wheel steering force is kept constant by a hydraulic block described later.

2) Club mode (rear wheel steering mode): A mode in which the front and rear wheels are steered in conjunction with the operation of the steering wheel 4, and the front and rear wheels are kept in the same phase so that the front and rear wheels have the same phase. Steered.

3) Clamp mode (rear wheel steering mode)
This is a mode in which the front and rear wheels are steered in conjunction with the operation of the steering wheel 4, and the front and rear wheels are steered so as to maintain the front wheel phase and the rear wheel phase in opposite phases.

4) Rear steering mode (rear wheel steering mode)
Only the rear wheels are steered in conjunction with the operation of the steering wheel 4. The front wheel steering force is kept constant by a hydraulic block described later.

In the present invention, the mode switching valve 3
The specific configuration and operation of the hydraulic circuit associated therewith are not particularly limited. An example is shown in FIG.

The circuit shown in FIG. 4 includes the mode switching valve 3 and the pilot check valve 60. The mode switching valve 3 includes a front wheel control switching valve 31 and a rear wheel control switching valve 3.
The two valves 31 and 32 are constituted by three-position electromagnetic pilot switching valves in this embodiment.

The front wheel control switching valve 31 is connected to the rod side of the left front wheel steering cylinder 1 and the head side of the right front wheel steering cylinder 1 via a line 41, and is connected to the left front wheel steering cylinder 1 via a line 42. It is connected to the head side and the rod side of the right front wheel steering cylinder 1. Rear-wheel control switching valve 32
Is the line 51 and the double pilot check valve 6
0 is connected to the head side of the left rear wheel steering cylinder 2 and the rod side of the right rear wheel steering cylinder 2, and is connected to the rod side of the left rear wheel steering cylinder 2 via the line 52 and the double pilot check valve 60. And, it is connected to the head side of the right rear wheel steering cylinder 2. Then, depending on the rotational operation direction of the steering wheel 4, the mode switching valve 3
Front wheel control switching valve 31 side or rear wheel control switching valve 32
Hydraulic oil is appropriately introduced from the side.

The position of the two switching valves 31 and 32 is switched by a mode switching signal (solenoid excitation signal) from the controller C.
The actual steering mode is switched by switching these positions. Specifically, in a state where both switching valves 31 and 32 are switched to the neutral positions 31b and 32b, respectively, as shown in the figure, the hydraulic circuit for the rear wheel steering cylinder 2 is blocked, and the hydraulic fluid is applied only to the front wheel steering cylinder 1. Is switched to the normal mode in which is introduced, and by other appropriate position switching, the mode is switched to various rear wheel steering modes.

For example, when the front-wheel control switching valve 31 is in the left position 3
1a, when the rear wheel control switching valve 32 is switched to the left position 32a, the hydraulic circuit for the front wheel steering cylinder 1 is blocked and the mode is switched to the rear steering mode in which hydraulic oil is introduced only to the rear wheel steering cylinder 2. ,
When the front wheel control switching valve 31 is switched to the neutral position 31b and the rear wheel control switching valve 32 is switched to the left position 32a, the mode is switched to the club mode in which the front wheels and the rear wheels are steered in the same phase. When the switching valve 31 is switched to the left position 31a and the rear wheel control switching valve 32 is switched to the right position 32c,
The mode is switched to the clamp mode in which the front wheels and the rear wheels are steered in opposite phases.

The double pilot check valve 60 is for more securely hydraulically locking the rear wheel.
It is provided with two check valves 60a and 60b,
0a is provided in the line 51, and the check valve 60b is provided in the line 52. When the primary pressure of the check valve 60a becomes higher than a certain value, the check valve 60b opens, and the primary pressure of the check valve 60b becomes higher than a certain value. In this case, the check valve 60a is configured to be opened when it becomes. here,
The set pressure serving as a boundary for opening the check valves 60a and 60b is set sufficiently higher than the pressure generated due to the oil leaking from the spool of the rear wheel control switching valve 32.

With this configuration, when the mode is switched to the normal mode by the mode switching valve 3, the hydraulic lock by the double pilot check valve 60 is automatically performed, so that the safety in the normal mode traveling is further improved. be able to.

On the other hand, as means for mechanically locking the rear wheel, a lock hole 9 is provided on the rear wheel side, and a lock pin (rear wheel lock means) 8 is provided near the lock hole 9. The lock pin 8 is driven to expand and contract by a pneumatic lock cylinder 7, and the rear wheel is in a neutral position.
Further, it is disposed at a position where it is inserted into the lock hole 9 when the lock cylinder 7 is extended. When the lock pin 8 is inserted into the lock hole 9, the rear wheel is locked or locked at the neutral position. Conversely, when the lock pin 8 is removed, the lock is released.

The lock cylinder 7 is connected to an electromagnetic lock switching valve 10 for controlling the expansion and contraction operation. The electromagnetic lock switching valve 10 is connected to an air tank 11 as an air pressure supply source for the lock cylinder 7. I have.
The lock pin 8, the lock hole 9, the lock switching valve 10, and the air tank 11 constitute a rear wheel locking device that switches between a state where the rear wheel is locked at the neutral position and a state where the rear wheel is released.

The steering control device further includes a neutral position detecting switch (for example, a limit switch) for detecting whether or not the front and rear wheels are respectively in a state parallel to the straight traveling direction of the crane, that is, whether or not the front and rear wheels are at a neutral position. 1
3, 14; a vehicle speed sensor 16 for detecting a traveling speed (vehicle speed) of the work machine;
A mode selection switch (mode selection means) 17 for selecting one of the four modes and an output changeover switch 19 are provided, and these output signals are input to the controller C.

FIG. 2 shows an example of the arrangement of the mode selection switch 17 and the output changeover switch 19. In the figure, a steering wheel 4 is disposed in front of a seat 12, and the output changeover switch 1 is provided at an appropriate position on the steering wheel 4.
9 are provided. The mode selection switch 17 is provided on a panel in front of the seat 12 and, for example, a C
A display section 18 made of RT is provided.

Next, the configuration of the controller C will be described. The controller C includes a mode switching control unit 21, a lock operation control unit 22, and a warning unit 23 as shown in FIG.

The mode switching control means 21 performs switching control of the mode switching valve 3 based on a switching command signal from the mode selection switch 17 and a detection signal from the neutral position detection switch 14. The lock operation control means 22 performs operation switching control of the rear wheel locking device, that is, switching control of the lock switching valve 10, based on a switching command signal from the mode selection switch 17 and a detection signal from the neutral position detection switch 14. The warning means 23 includes the neutral position detection switch 1
Based on the output signals 3 and 14, when there is a difference between the timing at which the front wheels return to the neutral position and the timing at which the rear wheels return to the neutral position, the display unit 18 displays a warning.

In addition, the controller C is connected to the display unit 1
8 is configured to display the current steering mode and the detection result by the neutral position detection switch 14.

Next, a specific control operation performed by the controller C will be described with reference to the flowchart of FIG.

First, when the rear wheel steering mode, that is, any one of the club mode, the clamp mode, and the rear steering mode is selected by the mode selection switch 17 (NO in step S1), the lock operation control means 22 sends the lock switching valve 10 The control signal is output to
The locking device is automatically switched off (step S
2) The lock of the rear wheel is released. At the same time, by outputting a control signal from the mode switching control means 21 to the mode switching valve 3, the actual steering mode is switched to the rear wheel steering mode selected by the mode selection switch 17 (step S3). Wheel steering is enabled.

On the other hand, when the normal mode is selected by the mode selection switch 17 (YE in step S1).
S), it is determined whether the output switch 19 is on or off (step S4). When the output changeover switch 19 is off (NO in step S4), the following automatic centering processing is performed instead of immediately switching to the normal mode.

First, based on the output signal of the neutral position detection switch 14, it is determined whether or not it is detected that the rear wheel is at the neutral position (step S6). If it is not at the neutral position (NO in step S6), the current mode (rear wheel steering mode) is maintained. Then, when the neutral position is detected (for example, when the driver operates the steering wheel 4 to return the rear wheel to the neutral position; YE in step S6)
For the first time in S), the locking device (lock cylinder 7 and lock pin 8) is operated to lock the rear wheels at the neutral position (step S7), and the actual steering mode is switched to the normal mode. Thus, normal traveling (travel in which only the front wheels are steered) can be performed in a safe state in which the rear wheels are locked.

Accordingly, by turning off the output changeover switch 19 in advance, it is possible to prevent a situation in which the driver suddenly forgets to return the rear wheel to the neutral position and suddenly switches to the normal mode. Yes, and high security can be obtained.

Even if the output changeover switch 19 is on, if the vehicle speed is higher than a certain value (N in step S5)
O) Also, the same auto-centering processing as described above is performed, and high security is guaranteed.

On the other hand, when the normal mode is selected by the mode selection switch 17, the output changeover switch 19 is on (YES in step S4), and when the vehicle speed is lower than a predetermined value (YES in step S5), The mode is immediately switched to the normal mode regardless of whether the rear wheel is at the neutral position (step S8). Therefore, the driver
By turning on the output change-over switch 19, it is possible to perform an operation in which only the front wheels are steered by the steering wheel 4 while maintaining the rear wheels at an arbitrary rear wheel steering angle. In other words, the output changeover switch 19 is driven by the driver's intention.
By switching between the normal mode and the rear wheel steering mode as appropriate while the vehicle is turned on, it is possible to operate the front wheel steering angle and the rear wheel steering angle while operating each independently. The width is increased, and it becomes possible to more easily cope with, for example, entry into a narrow place.

In addition, since the front and rear wheel steering angles can be set independently of each other, the front and rear wheels are simultaneously steered while maintaining a fixed relation, for example, in a club mode or a clamp mode. In the mode, the timing at which the front wheels return to the neutral position may deviate from the timing at which the rear wheels return to the neutral position. In such a case, the control signal of the warning means 23 causes the display unit 18 to indicate that. Is displayed, it is possible to prevent a situation in which the driver forgets to shift the neutral timing and drives.

The warning of the deviation of the neutral timing is not limited to the display of the warning on the display unit 18, but a buzzer may be sounded.

Whether or not to limit the switching to the normal mode depending on the vehicle speed may be appropriately set according to the specifications. That is, step S5 in FIG. 3 can be omitted as appropriate.

Alternatively, as shown in FIG. 5, regardless of whether the vehicle is in the normal mode or not, when the vehicle speed is higher than a predetermined value (step S0 in FIG. 5), the mode switching itself is prohibited and the current mode is maintained. You may make it.

The present invention also needs to include at least one mode (for example, only the rear steering mode) in the rear wheel steering mode. By switching between the mode and the normal mode, it is possible to realize a wide operation. Become.

[0052]

As described above, the present invention is provided with a changeover switch in addition to the mode selection means. When the changeover switch is off, switching to the normal mode is performed only when the rear wheel is in the neutral position. When the changeover switch is on, the switch to the normal mode at any rear wheel steering angle is allowed regardless of the rear wheel position. There is an effect that the degree of freedom of driving can be increased while maintaining safety, and higher steering performance can be exhibited.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a steering control device according to an embodiment of the present invention.

FIG. 2 is a plan view showing a cab of a working machine on which the steering control device is mounted.

FIG. 3 is a flowchart showing a control operation performed by the controller.

FIG. 4 is a hydraulic circuit diagram showing a configuration of a mode switching valve in the steering control device.

FIG. 5 is a flowchart showing another example of a control operation performed by the controller.

[Explanation of symbols]

 Reference Signs List 3 Mode switching valve (mode switching means) 4 Steering wheel (steering operation member) 7 Lock cylinder (constituting rear wheel locking means) 8 Lock pin (constituting rear wheel locking means) 13 Neutral position detection switch (front wheel neutral position detecting means) 14) Neutral position detection switch (rear wheel neutral position detection means) 16 Vehicle speed sensor 17 Mode selection switch (mode selection means) 18 Display section 19 Output switch 21 Mode switching control means 22 Lock operation control means 23 Warning means C controller

Claims (6)

[Claims] 1. A steering mode comprising: a normal mode in which only a front wheel is steered in conjunction with an operation of a steering operation member while a rear wheel steering angle is kept constant; A mode in which the rear wheels are steered and a mode is switched to a rear wheel steering mode including at least one of a mode in which only the rear wheels are steered and a mode in which the front and rear wheels are steered while keeping the relationship between the front and rear wheels constant. In a steering control device for a wheel-type work machine including switching means, a mode selecting means for selecting the steering mode, a rear wheel neutral position detecting means for detecting whether the rear wheel is at a neutral position, A changeover switch provided separately from the mode selection means, and a switch when the rear wheel steering mode is selected by the mode selection means. The steering mode is switched to the selected mode, the switch is off, and
When the normal mode is selected by the mode selection means, the steering mode is maintained at the current mode until the rear wheel neutral position detection means detects that the rear wheel is at the neutral position, and the rear wheel is neutralized. When it is detected that the steering wheel is in the normal position, the steering mode is switched to the normal mode. When the changeover switch is turned on and the normal mode is selected by the mode selection means, the rear wheel is in the neutral position. And a mode switching control means for immediately switching the steering mode to the normal mode regardless of whether the steering mode is set or not. 2. The steering control device for a wheel-type work machine according to claim 1, wherein a rear wheel locking means for locking a rear wheel at a neutral position, a steering mode is switched to the normal mode, and the rear wheel is provided. Lock switching control means for locking the rear wheel locking means when the neutral position detection means detects that the rear wheel is in the neutral position. A steering control apparatus for a wheel type working machine, comprising: . 3. The steering control device for a wheel-type working machine according to claim 1, wherein the changeover switch is provided on the steering operation member. 4. A steering control device for a wheel type working machine according to claim 1, further comprising a vehicle speed detecting means for detecting a vehicle speed of the working machine, wherein the vehicle speed detected by the vehicle speed detecting means is provided. Is greater than a certain value,
The mode switching control means is configured to prohibit switching to the normal mode when the rear wheel is not in the neutral position regardless of the on / off state of the changeover switch. apparatus. 5. The steering control device for a wheel-type work machine according to claim 4, wherein when the vehicle speed detected by the vehicle speed detection means is equal to or higher than a predetermined value, the current steering mode is set regardless of the mode selection by the mode selection means. A steering control device for a wheel-type working machine, wherein the mode switching control means is configured to maintain the condition. 6. The steering control device for a wheel-type work machine according to claim 1, further comprising a front wheel neutral position detecting means for detecting whether or not the front wheel is at a neutral position. The wheel steering mode includes a mode in which the front and rear wheels are simultaneously steered while maintaining a constant relationship, and in this mode, the timing at which the front wheels return to the neutral position and the timing at which the rear wheels return to the neutral position are shifted. A steering control device for a wheel-type work machine, comprising a warning unit for giving a warning.