JPH01266077A - Easily turnable skid steer vehicle - Google Patents

Abstract

PURPOSE:To carry out always stable turning by operating the rotating speeds of front and rear wheels from the detected result of the center of gravity position of a vehicle and the detected result of a required turning speed and controlling hydraulic motors for rotating each wheel in accordance with the operated result. CONSTITUTION:In the captioned vehicle applied to a shovel loader in which wheels 11-14 are driven by each hydraulic motor 30, which is fed with oil pressure from each hydraulic pump 81-84 driven by all engine 21, a load sensor 41 is provided on the lower portion of an arm 911 of a bucket 91. Also, slide sensors 43, 43 as required turning speed detecting devices for steering levers 93, 94 are provided thereon, and the outputs of the sensors are inputted into a controller 4. The controller 4 operates the center of gravity position and turning speed of the vehicle and determines the speed ratio between front and rear wheels. Then, based on the outputs of the slide sensors 43, the rotating speeds of right and left front/rear wheels are determined, controlling the discharging oil quantity out of the hydraulic pumps 81-84.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a skid steer vehicle such as a skid steer loader that is capable of stable turning.

[Prior art]

As shown in FIGS. 5 and 6, a skid steer shovel loader, which is a type of skid steer vehicle, first includes wheels 11 to 14 as drive wheels, a packet 91, and a bucket 91 on a machine base 90. Arm 9 for operating
11 and a safety guard 92. A total of four wheels 11 to 14 are provided, two at the front and rear on both sides of the machine base 90 of the shovel loader 9. Further, on the cough machine stand 90, there are hydraulic pumps 88, 89 as wheel drive devices and hydraulic motors 30, 30 driven by both hydraulic pumps. Drive shaft 50.5 of the hydraulic motor 30, 30
0 is connected to wheels 11-14 via chains 52,57.

Therefore, the left wheels 11 and 12 of the shovel loader 9 are moved by the motor 3 due to the pressurized hydraulic fluid generated in the hydraulic pump 88.
By rotating the drive shaft 50. Drive via chains 52,57. Left wheel 13.
14 is similarly driven by pressurized hydraulic oil from a hydraulic pump 89. This hydraulic pump 88,89 is operated by the engine 21.

Further, FIG. 4 shows the relationship between the left wheel 11, 12 and the hydraulic pump 8 in more detail.

This hydraulic pump 8 is a hydrostatic drive device (H5T)
is used. Therefore, the hydraulic pump 8 and the hydraulic motor 3
0 through a hydraulic pipe 22.

Subrockets 51 and 55 are fixed to the drive shaft 50 of the hydraulic motor 30 so as to be rotatable therewith.

In addition, the left front wheel (hereinafter referred to as front wheel) 11. Sprockets 53 and 56 are fixed to each axle shaft 54 of the left rear wheel (hereinafter referred to as rear wheel) 12.

A chain 52 is connected to the sprocket 51 of the drive shaft 50 and the sprocket 53 on the left front wheel 11 side. Similarly, the sprocket 55 of the drive shaft 50
A chain 57 is connected to the sprocket 56 on the left rear wheel 12 side. The same applies to the right front wheel 13 degrees and the right rear wheel 14.

As is known from the above, in the conventional skid steer vehicle, the left front wheel 11 and the left rear wheel 12, which are the left drive wheels, are both rotated at a constant speed by the hydraulic pump 8.

Further, the right front wheel 13 and the right rear wheel 14, which are right drive wheels, are both driven at a constant rotation by the hydraulic pump 9. The turning direction of the skid steer vehicle is controlled by the hydraulic pump 88.
This is done by tilting the steering lever (see FIG. 1) connected to 89 to create a difference in rotation between the left and right drive wheels.

[Problem to be solved]

However, in conventional skid steer vehicles,
Because the front and rear wheels rotate at the same speed.

When turning a skid steer vehicle, the turning is unstable. This is because the driving force of the front wheels is stronger, so the rotation of the rear wheels cannot keep up with the turning motion and is dragged.

This point will be explained using FIG. 3. In the figure, numerals 11, 12, 13 and 14 are the left front wheels.

They are a left rear wheel, a right front wheel, and a right rear wheel. Further, 0 is the center of the four driving wheels, OI is the vehicle center of gravity, 0□ is the turning center, ω is the turning angular velocity, and R is the distance from the turning center.

(2) is the speed of the wheel center point, θ is the angular difference between the wheel rotation direction and the turning direction, and FR is the front of the vehicle. Others are shown below.

As shown in the figure, 1 center of gravity 0. was undefeated with 0 vehicle-centered
It's shifted forward. The shift in the center of gravity causes a difference in the frictional force between the front wheels and the rear wheels, and as a result, the turning center 0□ moves forward compared to the vehicle center O. In addition.

The turning center 02 moves in the left-right direction due to the rotation difference between the left and right wheels.

When the vehicle is turning around the turning center 02 at a turning angular velocity ω, the center of the front wheels is VFL (=R
Fω), the center of the rear wheel has a speed of V++t (=R*ω) (VFL<VIL) - However, the center speed of the wheel obtained from the rotation of the wheel is that the front wheel has a speed of VFI (=V, *CosθF)
, the rear wheel is Vi+ (=V* *Cosθ8), and V,
=VR, θ, kuθ, so V, , >V□.

However, since the driving force of the front wheels is stronger than that of the rear wheels, if V FL ``i V y 1, then VI
L>>Vl. In other words, the rotation of the rear wheels cannot keep up with the turning motion, causing the vehicle to be dragged, making the front wheels unstable. Unstable turning also occurs because the turning time changes depending on the amount of load loaded on the packet. For example, the time it takes to turn 180 degrees is not stable.

In view of the problems of the prior art, the present invention enables stable turning. It is an object of the present invention to provide a skint steer vehicle that is easy to turn.

[Means for solving problems]

The present invention consists of a skid comprising nine machines, a total of four drive wheels, two wheels on both sides of the machine, two on the front and back, a hydraulic motor that rotates the nine drive wheels, and a hydraulic pump that drives the hydraulic motor. In a steered vehicle.

The machine base includes a load sensor for detecting the amount of load, a center of gravity position detection device for detecting the center of gravity position of the vehicle based on a signal from the load sensor, and a required turning speed detection device for the vehicle;
A control device is provided that calculates the rotation speed of the front wheels and the rear wheels based on the signals from the center of gravity position detection device and the required turning speed detection device, and the rotation speed of the front wheels and the rear wheels is controlled by the control device. This is a skid steer vehicle that is easy to turn.

In the present invention, the load sensor is a sensor that detects the amount of load of cargo loaded on a bucket or the like. The load sensor is 9
For example, a device that detects the bucket volume vi weight or lift cylinder pressure is used, and is installed at a position where the load amount can be detected.

In addition, the 5 center of gravity position detection device detects the center of gravity position of the vehicle when it is loaded based on the signal value equivalent to the load amount from the load sensor and the predetermined position of the center of gravity of the vehicle itself. It is a device for detecting. The required turning speed detection device is a device that detects the turning speed of the vehicle desired by the driver, and the turning speed is determined by detecting the movement of a steering lever used for turning the vehicle using a slide sensor.

Further, the control device determines the turning center 0 from the signals from the center of gravity position detecting device and the required turning speed detecting device, and calculates the rotation speed of the front wheels and rear wheels based on it as shown below.
This controls the rotation speed of the front and rear wheels.

That is, when a certain weight of cargo is loaded on the packet of the shovel loader, the vehicle center of gravity O5 is located in front of the four drive wheels in FIG. 3. At this time, 5 turning center 02 is the vehicle center of gravity 0. It is centrally determined based on the position of , and the difference between the front and rear wheels based on the difference in tire friction force of the driving wheels, and is located on the straight line 21.

Note that the turning center moves on ff1ffi due to the rotation difference between the left and right wheels.

Here, to simplify the explanation, we will set a scene where only the left wheel rotates forward. At this time, if the circumferential component of the center speed of the left front wheel is □ζ■ from the explanation of the prior art, then the circumferential component of the center speed of the left rear wheel is V, >> It becomes V□.

Here, V, that is, the rear wheel rotation is increased so that the speed ■□ caused by the rotation of the rear wheels matches the speed ■□ caused by the rotation of the single machine.

The rotation ratio between the front wheels and the rear wheels is determined by a quadratic equation.

Rear wheel/front wheel rotation ratio (w*/WF) = (R*/
R,)x(Cosθy/COSθ,l) Also, the third
As can be seen from the figure, a quadratic relationship holds true.

V*t=R++ ・ω=■□TomiV, Cosθ.

VFL-RF　’　ω=Vy+-Vy　COSθ.

Vll=RA・W8 Vr=RA' WF In the above formula, RA is the radius of the wheel, W, and W are the wheel rotation speeds of the rear wheel and the front wheel. Also, as can be seen from the figure, from the position of the turning center 0□, R,, R,, θ,
9 θ, is determined centrally.

As described above, by determining the position of the center of gravity of the vehicle, the optimal value of the ratio of the rotational speeds of one front and rear wheel is determined in an integrated manner.

This applies even if the turning center 0□ is not on the machine center line.

However, in terms of controlling the rotation speed of the front and rear wheels.

There is stepless control as shown in the first embodiment, or stepwise control as shown in the second embodiment.

[Operations and Effects] In the present invention, as described above, the center of gravity of the vehicle is detected by the first center of gravity position detection device, the turning speed of the vehicle is detected by the required turning speed detection device, and the rotation of the front and rear wheels is controlled by the control device. controlling the number.

In this control, in the case of forward turning, the rear wheels have a higher rotation speed than the front wheels.

Therefore, according to the present invention, when the vehicle turns, the rotation of the rear wheels does not keep up with the turning motion and drag, and the rear wheels rotate smoothly. Therefore, it is possible to provide a skid steer vehicle that can stably turn and is easy to turn.

〔Example〕

First example For this example skid steer shovel loader.

The skid steer vehicle of this example, which will be explained with reference to FIG. 1, controls the rotation of the front wheels and rear wheels in a stepless manner.

The device of this example first has a left front wheel 11 as a driving wheel on both sides of the machine base 90. Left rear wheel 12. It has a right front wheel of 13 degrees and a right rear wheel of 14 degrees. The left front wheel 11 is connected to a hydraulic motor 30 via a drive shaft 31. The hydraulic motor 30 is
It is connected to a hydraulic pump 81 by a hydraulic pipe 22.

Similarly, the left rear wheel 12 is operated by a hydraulic pump 83.
The front right wheel 13 is connected to a hydraulic pump 82, and the rear right wheel 14 is connected to a hydraulic pump 84. The above-mentioned hydraulic pumps 81 to 84 use the above-mentioned H3T.

Further, below the arm 911 of the packet 91.

A load sensor 41 is provided. In addition, steering levers 93 and 94 are used to perform turning operations of the vehicle.

At the tips of the connecting rods 931 and 941, slide sensors 43 and 43 are provided as required turning speed detection devices. The control box 4 is connected to signal cables 42.44 from the load sensor 41 and slide sensors 43.43. Further, in the control box 4, a signal cable 45 is connected to hydraulic pumps 81 to 84. Further, reference numeral 21 is an engine for rotating the four hydraulic pumps 8.

The device of this example is configured as described above.

It exhibits the following effects.

That is, when the baggage 99 is loaded on the packet 91, the load amount is detected by the load sensor 41, and the signal thereof is input to the control box 4. Also, when a turn is instructed by operating the steering lever 93 or 94 while driving, a signal corresponding to the turning speed of one aircraft is sent to the slide sensor 4.
3 and 43 are input to the control box 4.

In the control box 4, the center of gravity position is detected based on the signal from the load sensor 41.

Further, the turning speed is detected based on a signal from the slide sensor 43. In addition, the control box is as described above (
, based on these detected values, the front wheels.

It calculates the rotation speed of the rear wheels and controls the rotation speed of both nine wheels.

That is, the control box 4 has the functions of the center of gravity position detection device, required turning speed detection device, and control device.

However, the calculation of the rotation speed of the front wheels and rear wheels is as follows.

It is performed using the above formula, and the calculation flow is based on the load sensor 41.
Based on the signals from the vehicle, the center of gravity O19 of the vehicle and the center of rotation Ox are calculated, and the rotation ratio of the front and rear wheels is determined.

Next, the rotational speed of the right front and rear wheels is determined based on the signal (turning speed) from the slide sensor 43 on the right steering lever 93 side. Furthermore, based on the signal from the slide sensor 43 of the left steering lever 94, the rotational speed of the left front and rear wheels is determined.

Next, based on the calculation result in the control box 4, the amount of hydraulic oil delivered from the hydraulic pumps 81 to 84 to each hydraulic motor 30 for driving each drive wheel 11 to 14 is controlled.

That is, the rotation of the hydraulic motor of each drive wheel is rlliH.

Each drive wheel rotates according to the rotation speed of this hydraulic motor. Therefore, each drive wheel rotates at an appropriate rotation speed according to the turning speed of the nine machines loaded in the packet, and the skid steer vehicle You can turn smoothly. Further, this rotation speed control is stepless.

Second Embodiment In this embodiment, when it becomes necessary to change the rotation ratio of the two front and rear wheels due to the movement of the center of gravity, the rotation ratio of the two wheels is changed in two steps. This will be explained using FIG. This figure shows the relationship between the front and rear wheels on the left side.

First, the front wheel 11 is connected to a sprocket 53 via an axle shaft 54. Furthermore, sprockets 68 and 56 are provided at two locations on the axle shaft 54 of the rear wheel 12. The sprocket 68 is connected via the chain 67,
It is connected to the sprocket 66 of the first clutch plate 65. Also, one sprocket 56 is connected to the chain 57 by
The second clutch is connected to the sprocket 59 of the temporary clutch 58. A clutch 62 is interposed between the first and second clutch plates 65,58. The clutch shaft 621 of the clutch 62 has a spline structure that allows both of the clutch shafts 621, which are fitted onto the drive shaft 61, to slide. The clutch 6'2 is pressed against and connected to the first clutch plate 65 or the second clutch plate 58 by rotating its link 64 by the solenoid valve 63.

Further, the drive shaft 61 is connected to a hydraulic motor 30, and the hydraulic motor is connected to a hydraulic pump 8 via a hydraulic pipe 22, as in the first embodiment.

Further, the drive shaft 61 includes a sprocket 51,
Through the chain 52, the sprocket 53 on the front wheel side
Connect with.

The device of this example is configured as described above.

It exhibits the following effects.

That is, when the vehicle is traveling straight, the clutch 62 is connected to the first clutch plate 65. Therefore, first, the front wheel 11 is connected to the sprocket 51 of the drive shaft 61. Chain 52. Rotated by an axle shaft 54.

The rear wheel 12 has a drive shaft 61. Clutch 62° 1st
Clutch provisional 65. The two rotate through a chain 67 and have the same rotation speed.

Next, when the vehicle turns, as shown in the first embodiment, when the control device needs to increase the rotation ratio between the front wheels 11 and the rear wheels 12 to a certain value or more (for example, 1.1), the solenoid valve 63 activates the clutch. 62 to the second clutch plate 58. The sprocket 59 of the second clutch plate 58 has more teeth than the sprocket 66 of the first temporary clutch 65.

Therefore, sprocket 59. Chain 57. The rotational speed of the rear wheel 12 rotated via the sprocket 56 is higher than when the vehicle is traveling straight. At this time, the front wheels 11 are only driven by the drive shaft 61 via the chain 52. Therefore, the rotation speed of the rear wheels 12 is higher than that of the front wheels 11.

As described above, according to this example, when it is necessary to increase the rotation ratio of the front and rear wheels to a certain value or more during the above-mentioned turning, this can be changed into two stages using the clutch. Other effects similar to those of the first embodiment can be obtained.

In this example, by changing the clutch structure, it is possible to change the rotation of the front and rear wheels in 3 to 5 steps.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the skid steer vehicle according to the first embodiment, FIG. 2 is a similar explanatory diagram according to the second embodiment, FIG. 3 is a diagram illustrating the turning state of the drive wheels, and FIG. FIG. 5 is a side view of a shovel loader, and FIG. 6 is an explanatory diagram of control of the conventional skid steer vehicle. 11-14...wheels. 21...Engine. 22... Hydraulic piping. 30...Hydraulic motor. 4...Control box. 62...Clutch. 8.81-84.88.89...Hydraulic pump. 93.94...Steering lever. Applicant Toyoda Automatic Sewing Machinery Co., Ltd. Representative Patent Attorney Yoshiyasu Takahashi Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] A machine base, a drive wheel having a total of four wheels, two wheels at the front and back on both sides of the machine base, a hydraulic motor that rotates the drive wheel, and a hydraulic pump that drives the hydraulic motor. In the skid steer vehicle, the machine base includes a load sensor for detecting the amount of load, a center of gravity position detection device for detecting the center of gravity position of the vehicle based on a signal from the load sensor, and a device for detecting the required turning speed of the vehicle. ,
A control device is provided that calculates the rotation speed of the front wheels and the rear wheels based on the signals from the center of gravity position detection device and the required turning speed detection device, and the rotation speed of the front wheels and the rear wheels is controlled by the control device. A skid steer vehicle that is easy to turn.