JP3181129B2 - Anti-slip device for wheel-type construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip prevention device for a wheel type construction machine such as a wheel loader.

[0002]

2. Description of the Related Art In a wheel-type construction machine such as a wheel loader, when excavating work by operating a bucket, a boom or the like of a working device while running a vehicle by a traveling device,
When a slip occurs between a wheel (tire) and a road surface, work efficiency is reduced, and wear and damage to the wheel are increased.

[0003] In order to prevent the above-mentioned slippage, the operator generally relies on the experience and intuition of the boom lever and the bucket lever based on the degree of penetration of the bucket into the object to be excavated, the operating speed of the bucket, changes in the sound of the prime mover, and the like. The amount of operation or the amount of depression of the accelerator pedal is adjusted. However, it is very troublesome to prevent the wheels from slipping by manual operation in this way, and the physical and mental fatigue of the operator is great, and the control is inaccurate.

[0004] As a means for automatically controlling so as not to cause a slip, a slip prevention device disclosed in JP-A-63-189535 is known. In this conventional device, the rotational speeds of the left front wheel and the right front wheel are detected, the slip of the wheel is detected based on the rotational speed difference, and on the other hand, the rotational angle of the boom and the rotational angle of the bucket are detected.
The supply pressure to the boom cylinder and the supply pressure to the bucket cylinder are detected, and the engagement pressure of the power transmission clutch in the traveling device is controlled based on these detected values.

[0005]

According to the above-mentioned conventional apparatus, there is a problem that a large number of sensors are required and the cost is high.

The present invention solves the above-mentioned conventional problems, reduces the number of detection means, simplifies the equipment configuration and arithmetic processing, reduces costs, and allows an unskilled operator to operate efficiently without slipping wheels. The purpose is to be able to.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a wheel type construction machine, comprising: a pressure detecting means for detecting a discharge pressure of a hydraulic pump for a working device; Torque detecting means for detecting, a limit value calculating means for determining a limit value of a transmission shaft torque for preventing a wheel from slipping based on the pump discharge pressure detected by the pressure detecting means, and a transmission detected by the torque detecting means. Control means for controlling the engaging pressure of the traveling clutch so that the shaft torque does not exceed the limit value obtained by the limit value calculating means (claim 1). Instead of detecting the torque of the transmission shaft, the rotation speed of the prime mover and the rotation speed of the transmission shaft are detected, the torque of the transmission shaft is calculated based on the detected values, and the torque of the transmission shaft is calculated based on the calculated transmission shaft torque. It may be controlled (claim 2).

On the other hand, the clutch engagement pressure is detected so that the detected clutch engagement pressure does not exceed the clutch engagement pressure corresponding to the limit value of the transmission shaft torque obtained by the limit value calculating means. The clutch engagement pressure may be controlled (claim 3).

When the limit value of the transmission shaft torque is obtained by the limit value calculating means, reference value setting means for variably setting the reference value may be provided.

According to the above construction, when the wheel-type construction machine is operated, the discharge pressure of the working equipment hydraulic pump, which changes according to the load of the working equipment, is detected, and the traveling device corresponding to the traction force of the machine is detected. Of the transmission shaft is detected (claim 1), or the transmission shaft torque is obtained by calculation (claim 2). Then, based on the pump discharge pressure, a limit value of the transmission shaft torque for preventing the wheels from slipping is calculated, and the detected or calculated transmission shaft torque is controlled so as not to exceed the limit value. The engagement pressure is controlled, so that the wheels are operated so as not to slip.

According to the third aspect of the present invention, the discharge pressure of the working device hydraulic pump and the engagement pressure of the traveling clutch are respectively detected, and the wheels are slipped based on the detected pump discharge pressure. A limit value of the transmission shaft torque for preventing the transmission clutch is determined, and the engagement pressure of the traveling clutch is controlled such that the detected clutch engagement pressure does not exceed the clutch engagement pressure corresponding to the limit value of the transmission shaft torque. And the wheels are driven so as not to slip.

When the limit value of the transmission shaft torque is obtained, by changing the reference value according to the road surface condition or the like, optimal control is always performed, and wheel slip is more reliably prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a wheel type construction machine to which the present invention is applied will be described with reference to FIG. The wheel type construction machine includes a front frame 11, a rear frame 12, a cab 2
0, a prime mover 30, a traveling device 40, and a working device 50.

The motor 30 is provided with a fuel injection pump 32 having a fuel injection amount adjusting actuator 31. The driver's cab 20 is provided with an accelerator pedal 21,
By this pedal operation, the actuator 31 is operated via the link 22, the fuel injection amount by the fuel injection pump 32 is adjusted, and the rotation speed of the prime mover 30 is controlled.

The traveling device 40 includes a torque converter 41, a transmission 42, drive shafts 43 and 44, axles 45 and 46, and wheels 47 and 48 connected to the prime mover 30. Then, when traveling, the prime mover 30
Output from the wheel 4 through the torque converter 41 in the above order.
7, 48, and are driven to travel.

The working device 50 includes a front frame 11, a boom 54, a boom cylinder 55, a bucket 56, a bucket cylinder 57, a dump link 58, a cross link 59, and the like. The control valve 52 is switched by operating the operation lever 51 provided in the operator's cab 20, and the hydraulic pump 53 for working equipment is switched.
Is supplied to the boom cylinder 55 and the bucket cylinder 57 via the control valve 52, and the cylinders 55 and 57 are operated to expand and contract, and the boom 54
And the bucket 56 is rotated, and operations such as excavation are performed. The working device hydraulic pump 53 is driven by the prime mover 30.

In the above operation, the output of the prime mover 30 is preferentially distributed to the hydraulic system such as the hydraulic pump 53 of the working device 50 via the torque converter 41, and the remainder is consumed as power for the traveling device 40 via the torque converter 41. Is done. When the working device 50 is not operating, almost all of the output of the prime mover 30 is consumed by the traveling device 40 except for a part of the loss horsepower.

FIG. 5A shows a general relationship between the traveling speed of the vehicle body and the traction force when the wheel-type construction machine is operated. In FIG. 5A, a solid line A indicates a case where the working device hydraulic pump 53 is not loaded, a solid line B indicates a case where the working device hydraulic pump 53 is medium-loaded, and a solid line C indicates a case where the working device hydraulic pump 53 is heavy.

Referring to FIG. 5A, the following can be said as characteristics of the relationship among the load, the traction force, and the traveling speed of the working device hydraulic pump 53.

1) When the load on the hydraulic pump 53 for working equipment increases, the traction force decreases and slipping becomes difficult.

2) A large load on the hydraulic pump 53 indicates that a large digging resistance is acting on the working device 50, and the vertical component of the digging resistance at that time increases the pressing force of the vehicle body against the ground. Will be.
Along with this, the frictional resistance between the wheels and the road surface increases,
The wheel slip limit increases accordingly.

From the above, in order to prevent the wheels from slipping, the slip limit value (minimum value) when the working device hydraulic pump 53 is unloaded in FIG. ) Is marked with ○, and the maximum value of the slip limit value that changes according to the discharge pressure of the hydraulic pump 53 is set as ●, and changes between the two as shown by a solid line D according to the discharge pressure of the hydraulic pump 53. It can be said that it is sufficient to set the slip limit value and operate so as not to exceed the slip limit value indicated by the solid line D.

The coefficient of friction between the wheel and the road surface changes depending on the road surface condition. In such a case, a slip limit value with a reduced reference value can be set as shown by a dashed line C 'in FIG. 5B. You can say that it should be done.

In view of the above, the present invention intends to limit the engaging pressure of the traveling clutch by using the above-described characteristics and by a simple device configuration and calculation so that the wheels 47 and 48 do not slip. . The traveling clutch is
This is provided in the transmission 42 of the traveling device 40 shown in FIG. 4, and is operated by a hydraulic circuit shown in FIG.

That is, in FIG. 6, reference numeral 23 denotes a hydraulic pump, reference numeral 24 denotes a speed-stage switching control valve mounted on the transmission 42 (FIG. 4), reference numeral 25 denotes a traveling clutch, and reference numeral 26 denotes pressure control means. The hydraulic pump 23 is driven by a prime mover 30. During normal traveling, the operation of a clutch lever provided in the cab 20 activates the speed-stage switching control valve 24 of the transmission 42 to control the pressure oil supplied from the hydraulic pump 23 to the traveling clutch 25. Then, the running speed of the vehicle body and the clutch engagement pressure are controlled, and the traction force is controlled. At this time, the pressure control means 26 is operated by a signal from the controller 70 (FIG. 1), and the clutch 25
Is controlled, that is, the clutch engagement pressure is controlled, and the upper limit of the traction force is limited. Hereinafter, a specific example of the control will be described.

Embodiment 1 FIG. 1 shows the discharge pressure Ph of the hydraulic pump 53 for working equipment,
FIG. 3 is a control block diagram in a case where the transmission shaft torque of the traveling device 40 is detected and the engagement pressure of the traveling clutch 25 is controlled. In FIG. 1, 61 is a pressure detecting means, 62 is a reference value setting means, 63 is a torque detecting means, 70 is a controller, 71 is a limit value calculating means, 72 is a comparing means, 73 is a command value calculating means, and 74 is an amplifying means. Is shown.

In the first embodiment, first, the pressure detection means 61 detects the discharge pressure Ph of the working device hydraulic pump 53 driven by the prime mover 30, and sends the detected value to the controller 70. On the other hand, the torque detecting means 6
3, the transmission shaft torque of the traveling device 40 is detected, and the detected value is sent to the controller 70. Note that the transmission shaft torque corresponds to the tractive force. In the first embodiment, the torque detection unit 63 detects the output shaft torque of the torque converter 41 (FIG. 4). Then, based on the discharge pressure Ph of the working device hydraulic pump 53 detected by the pressure detecting means 61 by the limit value calculating means 71,
Limit value Ts-limi of the transmission shaft torque (output shaft torque of torque converter 41) for preventing the wheels from slipping.
Calculate t (Equation 1).

[0028]

Ts-limit = Tso + a · Ph where Tso is a reference value and a is a constant. Next, the comparing means 72 detects the transmission shaft torque Tt detected by the torque detecting means 63 based on the following equation (2). When,
A deviation .DELTA.Tt from the limit value Ts-limit of the transmission shaft torque for preventing slippage calculated by the above equation 1 is obtained.

[0029]

ΔTt = Tt−Ts-limit Then, based on the deviation ΔTt, the command value calculating means 73
The control command value A of the engagement pressure of the traveling clutch 25
Find cc.

Here, as shown in FIG.
Pressure and clutch transmission torque (transmission shaft torque) are constant
There is a relationship between the detected transmission shaft torque and the deviation Δ
If Tt is known, the clutch command pressure control command value Acc
Is derived.

The increase / decrease value of the clutch engagement pressure can be obtained by multiplying the deviation ΔTt by a coefficient.

In this manner, a signal corresponding to the command value Acc of the clutch engagement pressure calculated by the command value calculation means 73 is amplified by the amplification means 74 and sent to the pressure control means 26. The upper limit is shown in FIG.
Is controlled as shown by a solid line D in FIG. FIG. 5 shows the effect of the control of the clutch engagement pressure in the case of the first embodiment and the limitation of the traction force due to the control.
(B). In FIG. 5 (b), the hatched portion is where the restriction is imposed. Example-2 FIG. 2 shows the discharge pressure Ph of the working device hydraulic pump 53,
The control block diagram in the case of detecting the rotation speed Ne of the prime mover 30 and the rotation speed Nt of the output shaft of the traveling device 40 to control the clutch engagement pressure is shown. In the first embodiment, the transmission shaft torque itself is detected, but in the second embodiment, control is performed using the transmission shaft torque obtained by calculation.

That is, in the torque converter 41 (FIG. 4), the transmission shaft torque Tt can be calculated from the ratio (speed ratio) between the input shaft rotation speed Ne and the output shaft rotation speed Nt.
In this case, once the size of the torque converter 41 is determined,
The torque ratio t and the input shaft torque coefficient τp are the speed ratio e
A certain relationship is established with respect to. Therefore, in FIG. 2, the rotation speed detection means 64 detects the rotation speed Ne of the input shaft of the torque converter 41, and the rotation speed detection means 65 detects the rotation speed Nt of the output shaft of the torque converter 41. Based on the characteristic data of the torque converter 41 stored in the storage means 75, the transmission shaft torque Tt is obtained by the torque calculation means 76 by the following equation.

[0034]

## EQU3 ## e = Ne / Nt

[0035]

## EQU4 ## t = t [e]

[0036]

Τp = τp [e]

[0037]

Tp = τp · (Ne / 1000) 2 Tt = t · Tp where Tp is the input shaft torque, and Tt is the transmission shaft torque. Thus, calculation is performed instead of the measured value of the transmission shaft torque in the case of the first embodiment. When the control is performed using the values, the operation and effect that the wheels can be efficiently driven so as not to slip can be obtained as in the case of the first embodiment.

In this case, as in Embodiment 1,
From the relationship between the transmission shaft torque and the clutch engagement pressure in FIG.
From the calculated transmission shaft torque Tt and deviation ΔTt, the clutch
The control command value Acc of the combined pressure can be obtained.

Embodiment-3 FIG. 3 shows the discharge pressure Ph of the working device hydraulic pump 53,
FIG. 3 shows a control block diagram in a case where clutch engagement pressure Aca is detected to control clutch engagement pressure. In this case, as shown in FIG. 7, there is a fixed relationship between the clutch engagement pressure and the clutch transmission torque (transmission shaft torque).
When the slip limit value is determined as shown by the solid line D in (b), the clutch engagement pressure corresponding to the limit value is determined by the limit value calculating means 71, and the clutch engagement pressure is determined by:
From the detected clutch engagement pressure Aca, the command value Acc of the clutch engagement pressure can be obtained.

Also in the case of the third embodiment, the operation and effect that the wheels can be operated efficiently so that the wheels do not slip can be obtained as in the case of the first and second embodiments.

In each of the above embodiments, the output shaft torque of the torque converter 61 is detected as the transmission shaft torque of the traveling device in order to know the traction force. The drive shaft torque may be detected or calculated.

In each of the above embodiments, when the limit value calculating means 71 calculates the slip torque limit value Ts-limit, the reference value Tso is set by the reference value setting means 62 such as a voltage regulator. It is desirable to set variably according to the situation and the like. In this way, optimal control is always performed, and wheel slip is more reliably prevented.

[0043]

As described above, according to the first aspect of the present invention,
Detects the discharge pressure of the hydraulic pump for work equipment that changes according to the load on the work equipment, and the transmission shaft torque of the traveling device corresponding to the traction force of this machine, and based on the pump discharge pressure, does not slip the wheels. The transmission shaft torque limit value is determined, and the slip of the wheels is suppressed by controlling the clutch engagement pressure so that the transmission shaft torque does not exceed the limit value. The operation can be performed efficiently and efficiently, and the energy saving effect can be enhanced. In addition, since only the discharge pressure of the hydraulic pump and the transmission shaft torque are detected, the number of detectors to be installed can be reduced as compared with the above-described conventional device, and the device configuration and arithmetic processing are simplified to reduce costs. Can be.

Instead of detecting the transmission shaft torque as in the second aspect of the invention, the rotation speed of the prime mover and the rotation speed of the transmission shaft are detected, and the transmission shaft torque is calculated based on the detected rotation speed.
Even when the control is performed, the same operation and effect can be obtained.

Further, the clutch engagement pressure is detected, and the detected clutch engagement pressure does not exceed the clutch engagement pressure corresponding to the limit value of the transmission shaft torque. By controlling the clutch engagement pressure, it is possible to operate efficiently so that the wheels do not slip as described above.

In this case, when the limit value of the transmission shaft torque is obtained, by changing the reference value according to the road surface condition or the like, optimal control can always be performed, and the slip of the wheels can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing an embodiment in which a discharge pressure of a hydraulic pump for a working device and a transmission shaft torque of a traveling device are detected to control an engagement pressure of a traveling clutch.

FIG. 2 is a control block diagram showing an embodiment in which a clutch engagement pressure is controlled by detecting a discharge pressure of a working device hydraulic pump, a rotation speed of a prime mover, and a transmission shaft rotation speed of a traveling device. .

FIG. 3 is a control block diagram showing an embodiment in a case where a clutch engagement pressure is controlled by detecting a discharge pressure of a working device hydraulic pump and an engagement pressure of a traveling clutch.

FIG. 4 is a conceptual diagram showing an example of a wheel type construction machine to which the present invention is applied.

FIG. 5A is a graph showing general characteristics of the wheel type construction machine, and FIG. 5B is a graph for explaining the operation and effect of the present invention.

FIG. 6 is a hydraulic circuit diagram of a traveling clutch according to the present invention.

FIG. 7 is an explanatory diagram showing a relationship between an engagement pressure of a traveling clutch and a transmission torque.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Front frame 12 Rear frame 20 Operator's cab 23 Hydraulic pump 24 Speed control switch valve of transmission 25 Travel clutch 26 Pressure control means 30 Prime mover 40 Traveling device 41 Torque converter 42 Transmission 43,44 Drive shaft 45,46 Axles 47, 48 Wheels 50 Working device 51 Operating lever 52 Control valve 53 Hydraulic pump for working device 54 Boom 55 Boom cylinder 56 Bucket 57 Bucket cylinder 58 Cross link 59 Dump link 61 Pressure detecting means 62 Reference value setting means 63 Torque detecting means 64 motor speed detecting means 65 output shaft speed detecting means of torque converter 66 reference value setting means 70 controller 71 slip torque limit value calculating means 72 comparing means 73 target value calculating means 74 amplifying means 75 Torque converter characteristic storage means 76 Torque calculation means 77 Clutch engagement pressure limit value calculation means

Continued on the front page. (72) Inventor Kenji Eda 3-124 Gion, Asaminami-ku, Hiroshima City Inside Aburaya Heavy Industries, Ltd. (72) Inventor Hiroshi Taji 3-12-4 Gion, Asaminami-ku, Hiroshima City, Aburaya (56) References JP-A-3-50034 (JP, A) JP-A-63-189535 (JP, A) JP-A-58-1223932 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) E02F 9/22 F16D 25/00

Claims (4)

(57) [Claims] 1. A pressure detecting means for detecting a discharge pressure of a hydraulic pump for working equipment, a torque detecting means for detecting a torque of a transmission shaft in a traveling device, and a pump discharge pressure detected by the pressure detecting means. Limit value calculating means for determining a limit value of the transmission shaft torque for preventing the wheels from slipping; and a traveling clutch so that the transmission shaft torque detected by the torque detection means does not exceed the limit value determined by the limit value calculation means. Control means for controlling the engagement pressure of the wheel-type construction machine. 2. A pressure detection means for detecting a discharge pressure of a hydraulic pump for a working device, a motor rotation speed detection means for detecting a rotation speed of a motor, and a transmission shaft rotation speed for detecting a rotation speed of a transmission shaft in a traveling device. Detecting means, a torque calculating means for calculating the torque of the transmission shaft based on the prime mover rotation speed and the transmission shaft rotation speed detected by the both rotation speed detection means, and a pump discharge pressure detected by the pressure detection means. A limit value calculating means for calculating a limit value of the transmission shaft torque for preventing the wheels from slipping based on the torque, and a travel so that the transmission shaft torque calculated by the torque calculation means does not exceed the limit value obtained by the limit value calculation means. Control means for controlling an engagement pressure of a clutch for use in a wheel-type construction machine. 3. A first pressure detecting means for detecting a discharge pressure of a hydraulic pump for working equipment, a second pressure detecting means for detecting an engagement pressure of a traveling clutch, and the first pressure detecting means. Limit value calculating means for determining a limit value of the transmission shaft torque for preventing the wheels from slipping based on the detected pump discharge pressure; and clutch engagement pressure detected by the second pressure detection means, the transmission shaft torque Control means for controlling the clutch engagement pressure so as not to exceed the clutch engagement pressure corresponding to the limit value of the above-mentioned limit value. 4. The apparatus according to claim 1, further comprising reference value setting means for variably setting a reference value for obtaining a limit value of the transmission shaft torque by said limit value calculation means. An anti-slip device for a wheel-type construction machine according to the above.