JP2619586B2 - Reach type forklift braking system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking device for a reach type forklift.

[0002]

2. Description of the Related Art In recent years, a reach type forklift capable of traveling in all directions has been proposed in which left and right road wheels are configured to be steerable. This will be described with reference to FIG.
A reach-type forklift (hereinafter simply referred to as a forklift) 1 supports a main body portion 2 and left and right straddle arms 20 projecting from the main body portion 2 so as to steer road wheels 5 and 6, respectively. 2 is provided with a drive wheel 4 steerable by a steering wheel 3.

[0003] The drive wheel 4
Swivel swing gear 17 mechanically linked to handle 3
The turning gear 17 is provided with a potentiometer 18 capable of detecting the amount of rotation of the turning gear 17, whereby the steering angle of the drive wheel 4 can be detected. Although not shown, caster wheels are arranged on the side of the drive wheel 4 in order to secure running stability.

[0004] A cargo handling device 7 is mounted between the straddle arms 20 so as to be able to slide back and forth and to be able to move up and down by a lift cylinder (not shown).

The load wheels 5 and 6 are rotatably supported by pivot brackets 8 and 9 that can pivot with respect to the straddle arm 20. The pivot brackets 8 and 9 have a transmission tool 10 such as a chain or a belt. The steering motors 11 and 12 are mounted via the motors 10 and 10, respectively. Therefore, the left and right road wheels 5, 6 are steered about the steering center points L, R by rotating the steering motors 11, 12, respectively.

The output shafts of the steering motors 11 and 12 have a potentiometer 1 capable of detecting the amount of rotation.
3 and 14 are attached so that the steering angles of the left and right road wheels 5 and 6 can be detected.

[0007] The main unit 2 is provided with a control device 16. The control device 16 includes the potentiometers 18, 1
The detection signals 3 and 14 are input, and thereby, the steering is controlled based on so-called Ackerman steering.

The Ackerman steering will be described based on the case where the lateral traveling mode is selected. As shown in FIG. 6, the right road wheel 6 is fixed at a right angle (θ _R = 90 °), and intersection P between the extension line H _F of the rotating shaft of the extension line of the 6 rotational axis H _R and the drive wheel 4 becomes the pivot axis of the forklift, the extension line of the rotation axis of the left load wheel 5 to said pivot center point P H _So that _L matches
In addition, the steering angle of the left road wheel 5 is controlled by turning around the one turning center point in theory, thereby minimizing the slip of each wheel.
And can maintain a smooth turning state.

[0009]

The brake device of the forklift 1 is provided only on the drive wheel 4, which is a driving wheel , and the left and right road wheels 5, 6 have a so-called free rotation direction. It is configured as a ring. Therefore, in the case of the traveling directions shown in FIGS . 6 and 9, if sudden braking is applied during traveling, the left and right road wheels 5, 6 roll around the contact point between the drive wheel 4 and the traveling road surface, There is a problem that the attitude angle of the forklift 1 changes greatly (φ in FIG. 9 ). Such a problem becomes a very important issue for a forklift that needs to be accurately aligned with a load.

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-described circumstances, and has as its object to provide a forklift braking device which suppresses a change in the attitude angle of a forklift as much as possible even during braking , and which achieves a reliable braking operation. It is in the thing.

[0011] The present invention provides a
Together comprise a road wheel which is steerable supported, means for detecting a steering angle of the left and right road wheel, and a drive wheel that is steered by a handle, and means for detecting the steering angle of the drive wheel, Dry
Extension of the rotation axis of the wheel and the left and right road wheels
Ackerman steering where the extension of the rotation axis of the
In <br/> reach truck capable of steering control of the steering angle of the left and right road wheel Te, Rutotomoni provided a braking operation detecting means for detecting a braking operation of the drive wheel of the reach truck, brake operation
Is detected, a small amount of the left and right road wheels
At least one wheel is an extension of the rotation axis of the drive wheel.
And the extension of the rotation axis of the left and right road wheels at one point
It is based on a configuration provided with a control device for steering to an unknown steering angle . In addition, each said extension line intersects
Is determined by projecting it on a plane as shown in FIG.
sell.

[0012]

According to the present invention, a forklift is to minimize the slippage of each wheel by the up <br/> Carman steering can be performed smoothly steering. Also, when a brake operation is performed to stop the forklift, at least one of the left and right road wheels is extended by the rotation axis of the drive wheel.
Line and the extension of the rotation axis of the left and right road wheels at one point
Steering is performed to a steering angle that does not intersect, that is, steering control is performed so as not to positively perform Ackerman steering. As a result, the de
The braking force of the live wheel, the frictional force between the B Dohoiru the running road surface (slip) is added, along with obtaining a more reliable braking effect can suppress the change in the attitude angle of the forklift that occurs during braking.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the drive wheel 4 is equipped with a known brake device (not shown).
The brake device employs a so-called deadman brake, which is released by depressing a brake pedal 22 provided in a driver's cab 21 and, when the brake pedal 22 is released, puts a braking state.

The brake pedal 22 is provided with a limit switch 23 as a brake operation detecting means capable of detecting the depressed state. FIG. 4 shows the depression amount of the brake pedal 22 and the limit switch 2.
3 is shown. In FIG. 4, when the depression amount of the brake pedal 22 is max, that is, when the brake pedal 22 is fully depressed, the braking state is released as described above.

Next, from the state where the depression amount k of the brake pedal 22 is max, the foot is gradually released from the brake pedal 22. When the depression amount k decreases, as described above, the braking device is accordingly actuated. Gives a braking effect between the drive wheel and the road surface,
Until the depression amount k of the brake pedal 22 is k2 <k, it is a so-called mechanical play stroke.

However, when the foot is further released from the brake pedal 22, the depression amount k of the brake pedal 22 becomes
When it is smaller than k2, the braking effect of the brake device is obtained on the drive wheel 4 in inverse proportion to the depression amount.

In this embodiment, when the foot is further released from the brake pedal 22 and the depression amount k of the brake pedal 22 satisfies k1> k, the braking effect of the brake device on the drive wheel 4 increases, and The braking action according to the invention is obtained. This will be described later.

FIG. 2 shows a block diagram of the control device 24 of the present invention. As shown in the figure, the control device 24 includes an A / D converter, a ROM storing programs and the like, a RAM serving as a working memory, an MPU serving as a microprocessor, and a D / A.
It comprises a converter and a motor controller 19, which are connected by a bus line or I / O.

The A / D converter receives the steering angle θ of the drive wheel 4 from each of the potentiometers 18, 14 and 13.
D and voltages corresponding to the steering angles θL and θR of the left and right road wheels 5 and 6 are input. Also, these signals are A /
It is converted to a digital signal by a D converter.

The detection signal of the limit switch 23 which can detect the depressed state of the brake pedal 22 is MPU
Are input to the I / O.

Based on the above signals, the MPU calculates the steering angles θL and θR of the left and right road wheels 5 and 6. Note that this calculation processing procedure is stored in the ROM.

The steering angles θL and θR of the left and right road wheels 5 and 6 calculated by the MPU are calculated based on the deviation between the calculation result and the current steering angle detection value. 6 is determined and is converted into an analog signal by a D / A converter.
Are output to the left and right steering motors 11 and 12 respectively.

The motor controller 19 has an MPU
A control signal is input through the I / O via the I / O, and controls such as forward rotation, reverse rotation of the steering motors 11 and 12, and forced lock in the event of an abnormality are performed.

Next, the operation of the present invention will be described with reference to the flowchart shown in FIG. First, the steering angles θL of the left and right road wheels 5, 6 for Ackerman steering,
Calculate θR (S1, S2). Here, the calculation method will be described. An orthogonal coordinate system having the origin (0, 0) as the steering center point D of the drive wheel 4 as shown in FIG.
Assuming that the coordinates of the steering center points L and R of the left and right road wheels 5 and 6 are (xL, yL) and (xR, yR), the extension line HR can be expressed as a linear equation of Formula 1.

(Equation 1)

Further, an extension line HF of the drive wheel can be expressed by the following equation (2).

(Equation 2)

When both are solved simultaneously, the coordinates (xP, yP) of the turning center point P can be expressed by Equations 3 and 4.

(Equation 3)

(Equation 4)

Therefore, the steering angle θL of the left road wheel
Can be obtained by Expression 5.

(Equation 5)

Next, it is checked whether the limit switch 23 for detecting the depressed state of the brake pedal 22 is ON (S3). If the limit switch 23 is OFF (N in S3), the Ackerman steering described above is performed. The steering angles .theta.L and .theta.R of the left and right road wheels 5 and 6 are output (S6).

If the limit switch 23 is ON (Y in S3), the steering angles θ _L and θ _R of the left and right road wheels are set to predetermined fixed angles θ _GL and θ _{GR in} this example.
(S4, S5, S6).

The fixed angles θ _GL and θ _GR of the steering angles of the left and right road wheels 5 and 6 are determined by the rotation axis of the drive wheel.
Extension of extension H _F and the left and right road wheels rotating shaft
As a steering angle at which H _L and H _R do not intersect at a single point, for example, as shown in FIG. The angles can be selected to be coincident.

According to this, even if the vehicle body tries to rotate around the drive wheel 4 due to the inertial force acting on the center of gravity of the forklift around the contact point between the drive wheel 4 and the traveling road surface, the left and right road wheels 5 , 6 is Hoi
Since the running direction of Lumpur is steered in a state that can not roll and perpendicular to the rotation direction of the vehicle body, a large frictional force F, as shown by the number 6 between the road surface is generated, the posture change of the forklift Can be suppressed as much as possible. Here, μ is a coefficient of friction between the traveling road surface and the left and right road wheels 5 , 6 .
N _L and N _R are the vertical forces of the left and right road wheels 5 and 6.

[0033] In addition, not the steering angle θ _GL of the left-right load wheel you adopt, a fixed value of θ _GR was interpreted as intended to be limited to the embodiments described above in the braking state. That is, in order to suppress the posture change when the forklift 1 stops, the left
Friction braking force on one or both of the right road wheels
Is sufficient, and this example merely exemplifies the one that achieves the maximum braking effect. Therefore, a fixed value of the steering angle of the left and right road wheels, said Ackerman
Ru der those which can be selected arbitrarily from becoming not angle and steering.

Further, in the present embodiment, an example in which both the left and right road wheels 5 and 6 are output as a fixed angle is illustrated, but the output may be performed on only one of the road wheels. In such a case, one of steps S4 and S5 can be omitted in the flowchart shown in FIG.

FIGS. 7 and 8 show another embodiment. In this example, a normal traveling mode (steering angles θL of the left and right road wheels 5, 6) similar to a normal reach type forklift is used.
θR is fixed to zero).

First, the steering angles θ _L , θ _R of the left and right road wheels 5, 6 are both set to zero (T1, T2), but the depression of the brake pedal 22 is detected as described above .
Ri (T3 in Y), an extension of the axis of rotation of the drive wheel H
_F and extension lines H _L and H of the rotation axis of the left and right road wheels
_As an example of the steering angle where _R does not intersect at one point, the fixed angles of θ _L and θ _R are determined so that the steering angles θ _L and θ _R of the left and right road wheels become substantially “C” shaped. You can do it. When the limit switch 23 is not turned on (N at T3), the straight traveling state is maintained.

Although described in detail above, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist of the present invention.

[0038]

According to the present invention, as a result of employing the above configuration,
Conventionally steer Ackerman by steering left and right road wheels
Was Tei generated at the time of braking of the reach truck that can be
The vehicle body attitude change, can be prevented by generating a frictional force generated by b Dohoiru. Therefore, accurate positioning can be performed on the load, which can contribute to improving the efficiency of the cargo handling work. Further, since the friction braking effect is obtained not only in the drive wheel but also in the road wheel, the braking distance can be shortened, and a safe operation can be performed.

[Brief description of the drawings]

FIG. 1 is a plan view of a reach type forklift used in the present invention.

FIG. 2 is a block diagram of a control device used in the present invention.

FIG. 3 is a flowchart illustrating an embodiment of the present invention.

FIG. 4 is a diagram illustrating a relationship between a depression amount of a brake pedal and a limit switch.

FIG. 5 is a plan view showing a braking state according to the present invention.

FIG. 6 is a plan view for explaining Ackerman steering.

FIG. 7 is a plan view showing a braking state according to another embodiment of the present invention.

FIG. 8 is a flowchart for explaining another embodiment of the present invention.

FIG. 9 is a plan view for explaining a braking state of a conventional reach-type forklift.

FIG. 10 is a plan view showing a conventional reach-type forklift.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reach type forklift 4 Drive wheel 5 Left road wheel 6 Right road wheel 13 Potentiometer 14 Potentiometer 18 Potentiometer 20 Straddle arm 22 Brake pedal 23 Limit switch 24 Control device

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shinobu Tanaka 2-1-1 Higashikamishi, Nagaokakyo-shi, Kyoto Japan Transport Equipment Co., Ltd. (56) References JP-A-57-121972 (JP, A) 53-126235 (JP, U)

Claims (1)

(57) [Claims] (1) The left and right straddle arms can be steered.
Comprises a supported road wheel, means for detecting a steering angle of the left and right road wheel, and de <br/> live wheel is steered by a handle, and means for detecting the steering angle of the drive wheel And the extension of the rotation axis of the drive wheel,
Acker where the extension of the rotation axis of the wheel intersects at one point
Steering angle of the left and right road wheels by man steering
In reach truck capable of controlling, the brake operation detecting means for detecting a shake <br/> over key operations to the drive wheel of the reach truck provided Rutoto
When a brake operation is detected, the left and right road
At least one wheel of the wheel
Extension line of the rotation axis and rotation line of the left and right road wheels
A control device that steers to a steering angle that does not intersect at one point
A braking device for a reach-type forklift, which is characterized by being radiated.