JPS5993560A - Slip preventing apparatus - Google Patents

Abstract

PURPOSE:To enable slip to be detected accurately by setting a criterion value of the slip corresponding to an articulate angle. CONSTITUTION:A rotation ratio K is calculated on the basis of the detected angle data input Dt of an articulate angle detector 34, and a proper insensible band is added to this ratio K to calculate a slip criterion value K'. Continuously, the rotation ratios K1-K12 between respective wheels are calculated from the input of rotational speeds W1-W4 of the respective wheels. The rotation ratios K1-K12 are compared with the slip criterion value K', and advance is made to the output 200 when all rotation ratios K1-K12 are less than the criterion value K' and to the output 210 when any one of the rotation ratios K1-K12 exceeds the criterion value K'. The output 200 sends the rotational speed output of an input shaft to a register 39 and the output 210 subtracts said rotational speed of the input shaft by a predetermined value to send the output to the register 39.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slip prevention device for a wheeled vehicle that steers by bending the vehicle body at the center.

For work vehicles such as wheel loaders and motor scrapers,
Very expensive tires are used, and prevention of tire wear has become a primary concern for users. If tire slip occurs in such a vehicle, not only will the tires wear out quickly, but if there are sharp falling rocks on the working ground, there is a risk that the tires will be damaged. In particular, in vehicles equipped with a variable capacity heavy torque converter, there are two routes: one route transmits the engine output to the wheels via the variable capacity torque converter, and the other route transmits the output to the work equipment without going through the variable capacity torque converter. There are two routes, and when the engine output is increased to increase the output of the work equipment during work, the traction force transmitted to the wheels also increases, and as a result slips are likely to occur.

Therefore, this type of vehicle is conventionally equipped with a syslip prevention device.

Conventional anti-slip devices detect the rotational speed of four wheels, calculate the rotational speed ratio between each wheel, and even if the calculated rotational speed ratio is one, the slippage prevention device can be set in advance.

When the output torque exceeds the slip determination reference value, the output torque to the wheels is controlled (output torque is reduced) to prevent slippage (stopping).

However, in conventional anti-slip devices, the slip judgment reference value must be set to a value larger than the maximum value of the rotational speed ratio between the inner and outer wheels that inevitably occurs during turning, and a dead zone for slip detection. There was a drawback that the amount was extremely large.

The present invention has been made in order to solve the above-mentioned drawbacks.According to the present invention, an object of the present invention is to provide a slip prevention device that has high slip detection accuracy and is capable of effective slip prevention. Detecting the articulation angle of the wheeled vehicle facing towards the vehicle, setting a slip judgment reference value corresponding to this articulation angle, and when even one rotational speed ratio between each wheel exceeds the slip judgment reference value, The output torque to the wheels is reduced.

The present invention will now be described in detail with reference to the accompanying drawings.

Figures 1 (,) and (b) are plan views of a wheel loader to which the slip device according to the present invention is applied, respectively, where Figure 1 (,) is when traveling straight and Figure 1 (lJ) is when turning. It shows.

This wheel loader is provided with a center pin 1 in the center of the vehicle body in order to improve maneuverability, and the center pin 1 rotatably connects a front wheel truck 3 having a packet 2 and a rear wheel truck 4. When steering, the center of the vehicle body is bent by extending and contracting a steering cylinder (not shown) disposed between the front wheel truck 3 and the rear wheel truck 4 ( (See Figure 1(b)).

Next, the rotation ratio between the inner ring and the outer ring during steering will be explained. FIG. 2 geometrically shows the relationship between the turning center 0 and various parts of the vehicle when the vehicle is articulated by an angle of 0 with respect to when the vehicle is traveling straight.

Now, as shown in Figure 2, the articulating angle is θ,
When the tread of the vehicle is t1 and the wheelbase is t, the turning radius (distance between the turning center 0 and the tread center to) of the vehicle is as follows. On the other hand, if the rotation ratio between the inner ring and the outer ring is K, then the following equation is obtained. Substituting the above equation (0) into equation (2), the rotation ratio I
(As is clear from Equation (3), only the articulation angle θ can be expressed as a variable for the rotation ratio between the inner ring and the outer ring. Now, the tread length t is 2.26tn, If the wheel pace length is 3.05 m, the relationship between the articulation angle θ and the rotation ratio is as follows:
The result will be as shown in the graph in the figure.

The slip prevention device according to the present invention shown in FIG. 4 will be described in detail based on the relationship between the articulation angle θ and the rotation ratio.

In FIG. 4, the output of an engine 11 is expressed by a hydraulic pump 1 for driving a working machine etc. via an appropriate power transmission means.
3 and the hydraulic clutch 141 of the variable capacity torque converter 14.

The hydraulic clutch 141 is slip-controlled by a servo valve 43, which will be described later, and controls the output torque from the engine 11. The driving force from the hydraulic clutch 141 is generated by other components of the variable capacity torque converter 14. It is applied to the transmission 15 via a torque converter 142 . The output from the transmission 15 is transmitted to the four wheels 19, 20, 21, 22 via appropriate gears 16 and differentials 17, 18.
transmitted to.

Speed sensors 23 and 24 are arranged on the input shaft and output shaft of the torque converter 142, respectively, to detect the rotational speeds of these and output signals with frequencies corresponding to the speeds. Detection No. 48 Si is added to the frequency-voltage converter 25, and the speed sensor 2
The detection signal 5oFJL of No. 4 is applied to an input/output circuit 27 of a CPU (central processing unit) 26, which will be described later. Similarly, speed sensors 28, 29t30 and 31 are arranged on the drive shafts of the wheels 19, 20, 21 and 22, respectively, to detect their rotational speeds and output signals with frequencies corresponding to the speeds. Detection signals Wt of speed sensors 28 to 31
~W4 is applied to the input/output circuit 27.

The traveling driving force setting device 32 sets the magnitude of the driving force (torque) to be transmitted to the wheels, and the set output is converted into a corresponding digital signal Dt by the analog-digital converter 33.
is converted into and added to the input/output circuit 27. artikiko t
- The angle detector 34 detects the articulating angle θ (see FIG. 2) formed between the front wheel truck and the rear wheel truck, and converts a signal corresponding to this detected angle into a digital signal using the analog-to-digital converter 35. It is converted into Dθ and applied to the input circuit 27.

ROM (read only memory) 3G is CPU2
A program showing the control procedure executed by 6 and a curve L! showing the relationship between the input shaft rotation speed and the output shaft rotation speed of the torque converter 142 when the output torque is constant for each torque magnitude. ,L.

L3,...Ln (see Figure 5) are memorized,
Its storage contents are read by CPU 26. The RAM (Random Access Memory) 37 is still
It constitutes a data storage section of the CPU 26, and its storage contents are written and read by the CPU 26.

The interrupt timer 38 operates for a predetermined period of time (for example, 100 m5ec
) Generates an interrupt signal St to the Samurai and applies it to the CPU 26. As a result, the CPU 26 is interrupted at the timing when the interrupt signal St is added, and the program being executed at that point is interrupted. Then, the routine LU shown in FIG. 6 is executed.

That is, (first, the CPU 26 inputs the setting data Dt of the traveling driving force setting device 32 (input 110)), the ROM
Of the curves L1 to Ln stored in 36, the data D
A curve corresponding to t is selected (process 120).

Next, the output shaft rotational speed of the torque converter 142 is input (input 130). In this input 130, for example, the generation interval or period of the output signal So of the speed sensor 24 is counted, the reciprocal of the counted value is calculated, and the result is inputted as the output shaft rotation speed. , the CPU 26 calculates the input shaft rotation speed corresponding to the output shaft rotation speed obtained at the input 130 based on the curve selected in the above process 120 (process 140).

Next, the detected angle data Dt of the articim rate angle detector 34 is input (150), and the above-mentioned equation (3) is calculated based on this data Dt and the preset tread length t1 wheel pace length t. , the rotation ratio Ki between the inner ring and the outer ring is calculated, an appropriate dead zone is added to this rotation ratio K, and ' is calculated as the slip determination reference value (process 160).
.

Next, input the rotational speed W1 to W4 of each wheel (17).
0), and from these rotation speeds, as shown in Table 1, the rotation ratio between each wheel is 1 to 1! Calculate (process 1
80).

The rotation ratio r(i~!!) calculated in process 180 and process 16
Compare ' with the slip judgment reference value calculated at 0, and set it to 1 for all rotation ratios! If the snow is less than the reference value, the output goes to 200, and if any one of the rotation ratios Kl- is greater than the reference value, the output goes to 210 (Judgment 19).
0).

The output 200 outputs the input shaft rotation speed calculated in process 140 to the register 39, and the output 210 outputs the input shaft rotation speed calculated in process 140 by a predetermined value to the register 39.
Output to 9.

That is, for example, among the curves L1 to Ln, the curve Ln indicating the set torque is selected, and the output shaft rotational speed obtained at the input 130 is set to n shown in FIG. (RPM), if it is determined that the slip has not occurred, the input shaft rotation number (RPM) is recorded in the register 39 as shown in the figure.
PM) is set and it is determined that a slip has occurred, the register 39 contains the input shaft rotation number (R
A numerical value smaller than PM) by a predetermined value is set.

After this, the CPU 26 returns to the original program from the routine LU.

The set value of the register 39 is the value set by the digital-to-analog converter 4.
0 into the corresponding analog signal Sr, which is applied to the subtracter 41.

The output signal of the frequency-voltage converter 25, that is, the voltage signal corresponding to the frequency of the detection signal St, is applied to the subtracter 41.
42 outputs a signal Se that detects the deviation of the input shaft rotational speed from the command value. The signal Se is then applied to the servo valve 43 via the amplifier 42 as a control signal.

As a result, the flow rate of the hydraulic oil passing through the servo valve 43 is changed, and accordingly, the pressing force of the hydraulic cylinder 141a of the hydraulic clutch 141, that is, the hydraulic clutch 141
As the holding pressure changes, the slip amount of the hydraulic clutch increases or decreases, and the output shaft rotational speed increases or decreases. Thus, the input shaft rotation speed of the torque converter 1420 is stored in register 3.
The hydraulic clutch 141 is controlled so as to be equal to the set value of 9.

Therefore, when it is determined that no slipping has occurred, the driving force (torque) transmitted to the wheels is controlled to always be equal to the driving force set by the driving force setting device 32, and the slipping is prevented. If it is determined that the driving force is generated, the driving force is controlled to be smaller than the driving force set by the driving force setting device 32. That is, in the latter case, the output torque is reduced and subsequent slip occurrence is prevented.

In this embodiment, the slip judgment reference value is calculated sequentially each time the articulation angle is input, but the invention is not limited to this, and the slip judgment reference value corresponding to the articulation angle may be stored in advance. Alternatively, the corresponding slip determination reference value may be read out based on the articulate angle.

As explained above, according to the present invention, the slip-Ill constant reference value is sequentially set based on the articial rate angle, that is, the rotation ratio between the inner ring and the outer ring that inevitably occurs during steering. This improves slip detection accuracy, which makes it possible to prevent slips early and prevent wear and tear on tires.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are plan views of a wheel loader to which the anti-slip device according to the present invention is applied, and Figure 2 shows the calculation of the rotation ratio between the inner ring and the outer ring in accordance with the articulation angle. Figure 3 is a graph showing an example of the relationship between articial rate angle and rotation ratio, Figure 4 is a block diagram showing an example of the slip prevention device according to the present invention, and Figure 5 is a graph showing the output. FIG. 6 is a graph showing the relationship between the input shaft rotation speed and the output shaft rotation speed of the torque converter for each torque magnitude when the torque is constant, and FIG. 6 is a flowchart illustrating the control procedure of the CPU. 14...Variable capacity torque converter, 23, 24゜2
8.29,30,31--speed sensor, 26 CP
U. 32... Travel driving force setting device, 34 Articulation angle detector, 43... Servo valve, 141... Oil pressure graph f, 142... Torque converter, θ... 7-
Ticulate angle. rlV':3 >jk4fJfljlffJf&Ill
(RPM)Figure 6 11

Claims (3)

[Claims] (1) In a wheeled vehicle that steers by bending the vehicle body at the center, there is an angle detector that detects the articial rate angle at the center of the vehicle body, and rotation speed detection that detects the rotation speed of the wheels using the angle detector. a calculation means for calculating a rotation speed ratio between each wheel based on the rotation speed detected by the rotation speed detector, and at least one of the rotation speed ratios calculated by the calculation means is set by the setting means. A slip prevention device comprising: a control means for reducing output torque to a wheel when the slip judgment reference value exceeds the specified slip judgment reference value. (2) The setting means calculates the rotation speed ratio of the inner ring and the outer ring based on the articulation rate angle detected by the angle detector, the tread length and the wheelbase length of the vehicle, and sets the rotation speed ratio to the calculated value. The slip prevention device according to claim 1, wherein the slip determination reference value is set in conjunction with the above slip determination reference value. (3) The control means reduces the output torque to the wheels by reducing the holding pressure of the clutch of a variable capacity torque converter comprising a clutch and a torque converter. Anti-slip device as described in section.