JPS6251787B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention proposes a completely new hydraulically driven vehicle.

As a hydraulic drive device, a combination of a variable displacement hydraulic pump and a fixed displacement hydraulic motor is known, but the hydraulic pump has a complicated structure and is expensive, and has poor transmission efficiency. Even if neutrality was chosen, there were drawbacks such as the risk of slight movement.

The present invention uses a constant displacement hydraulic pump, and this hydraulic pump is connected to one constant displacement hydraulic motor connected to each of the left and right wheels via a high-speed responsive oil passage switching valve. It is an object of the present invention to provide a hydraulically driven traveling vehicle which eliminates the drawbacks of conventional hydraulic drive devices or vehicles equipped with the same, and which also enables steering.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to drawings showing embodiments of a tractor. FIG. 1 is a side view of a tractor according to the present invention, and FIG. 2 is a hydraulic circuit diagram together with a block diagram of the main parts of the electric control system.

P is a fixed displacement hydraulic pump, and engine E
driven by. The suction port of the hydraulic pump P is connected to the oil tank, and the discharge port is a 4-port, 3-position switching type electromagnetic oil path switching valve (hereinafter referred to as a solenoid valve) 1l.
It is connected to hydraulic motors Ml and Mr through 1r. The first port 11l of the solenoid valve 1l is connected to the hydraulic pump P, the second port 12l thereof is connected to the first port 11r of the solenoid valve 1r, and the second port 12r is connected to the oil tank. The other two ports 11l', 1 of the solenoid valve 1l (or 1r)
2l' (or 11r', 12r') are connected to the inlet/outlet of hydraulic motor Ml (or Mr), respectively, and manual valves 2l, 2r are connected to these ports in parallel with motor Ml (or Mr). has been done.

The hydraulic motor Ml (or Mr) is directly attached to the left front wheel Fl (or right front wheel, not shown) as a hub, and when pressure oil is supplied in one direction, it rotates in the normal direction to move the aircraft forward. The left (or right) front wheel is driven, and when pressure oil directed in the other direction is supplied, the left (or right) front wheel is driven in order to reverse the flow and move the aircraft backward.

The solenoid valve 1l (or 1r) has two solenoids 1
3l, 14l (or 13r, 14r), and when the solenoid 13l (or 13r) is energized and excited, the first pressure oil supply position is selected, and the ports 11l (or 11r) and 11l' (or 11r' )
But also ports 12l (or 12r) and 12
l' (or 12r'), and the hydraulic motor Ml (or Mr) is supplied with pressure oil directed in the one direction, so that it rotates in the normal direction. On the contrary, solenoid 1
When 4l (or 14r) is energized and excited, the second pressure oil supply position is selected and port 11l (or 14r) is energized and excited.
1r) and port 12l' (or 12r'), and port 12l (or 12r) and 11l' (or 11
r'), and the hydraulic motor Ml (or Mr) is supplied with pressure oil directed in the other direction to reverse rotation. And solenoids 13l, 14
1 (or 13r, 14r), the neutral position shown is selected, and the hydraulic motor
The oil passage on the Ml (or Mr) side is sealed. In addition, the position of the solenoid valves 1l and 1r can be changed.
A type with high-speed response on the order of msec is used. The manual valves 2l and 2r are 3-port, 2-position switching type valves, and are normally operated by a hydraulic motor as shown in the figure.
Although the entrances and exits of Ml and Mr are blocked, when the operating lever 2 common to both manual valves 2l and 2r is operated and locked, the entrances and exits of the hydraulic motors Ml and Mr are communicated, and also communicated with the oil tank. It's becoming like that.

Next, solenoids 13l, 14l, 13r, 14
The configuration of the electric control circuit that controls the supply of electricity to r will be explained.

3 is a steering wheel. The traveling vehicle of the present invention is not equipped with a mechanical steering device, and steers by controlling the energization of the solenoid 13l etc. using electrical signals. Although it is sufficient to provide only a knob, since it is preferable for handling to perform steering operations using the steering wheel as in a normal vehicle, the steering wheel 3 is provided at a general position in front of the driver's seat. A steering angle detector 4 consisting of a rotary potentiometer or the like that moves in conjunction with the shaft to change the output voltage is provided at the base end of the shaft 3a that rotates integrally with the steering wheel 3. Voltage V ₄ is pulse generator 8
It is configured to be inputted to a controller 7 that controls the . Steering angle detector 4 based on rotation of steering wheel 3
Since the output voltage V ₄ is information indicating the steering angle, the controller 7 determines the form of the pulse signal to be issued to the pulse generator 8 based on this voltage V ₄ . Note that the steering wheel 3 and shaft 3a only rotate the potentiometer, so they may be of lightweight construction.

Reference numeral 5 denotes a speed change lever, which is installed near the driver's seat, and at its base end there is a rotary potentiometer or the like that changes the output voltage in conjunction with the forward and backward rotation of the speed change lever 5. A speed change amount detector 6 is provided, and its output voltage _V6 is also input to the controller 7. Based on this voltage _V6 , the controller 7 also generates a pulse generator 8.
Determine the form of the pulse signal to be emitted. Note that the speed change lever 5 may also be of lightweight construction.

The controller 7 is composed of a microcomputer, etc., and after digitally converting the input data, that is, V ₄ and V ₆ , makes the following judgments, and controls the pulse generator 8 based on the judgments described below.

First, when the voltage V ₄ whose information content is the steering angle is a constant voltage value V ₄ N, it is recognized that the steering angle is set to 0 in order to make the aircraft travel straight, and V ₄ is less than V ₄ N. Also larger V ₄ r (or smaller
V ₄ l), the aircraft is steered to the right (or left) to turn the aircraft to the right, and the steering angle is |V ₄ r
−V ₄ N| (or |V ₄ l−V ₄ N|), that is, the magnitude of this absolute value is recognized as the magnitude of the steering angle.

Next, when the voltage V ₆ whose information content is an instruction regarding gear shifting is a constant voltage value V ₆ N, it is recognized that the aircraft is stopped or the aircraft is about to stop traveling, and V ₆ When is V ₆ F larger than V ₆ N (or smaller V ₆ R), it is assumed that the aircraft is going to travel forward (or backward), and |V ₆ F−V ₆ N | (or | V ₆ R −V ₆ N |) is data related to the speed command, and the magnitude of this absolute value is recognized as the height of the command traveling speed.

The pulse generator 8 includes solenoids 13l, 14l,
For drive circuits 93l, 94l, 93r, 94r for supplying excitation current to 13r and 14r,
It emits pulse signals P ₃ l, P ₄ l, P ₃ r, and P ₄ r in the form commanded by the controller 7. The command of this pulse signal is the input signal recognized as described above, i.e.
It is basically determined by V ₄ and V ₆ as follows.

(1) When V ₆ = V ₆ N, no pulse signal is generated.

(2) When V ₆ = V ₆ F (however, V ₆ F > V ₆ N) Pulse signal to drive circuits 93l and 93r
P ₃ l and P ₃ r are emitted, and their duty ratios are
The magnitudes of V ₆ F−V ₆ N correspond.

(3) When V ₆ −V ₆ R (however, V ₆ R<V ₆ N) Pulse signal to drive circuits 94l and 94r
P ₄ l and P ₄ r are emitted, and their duty ratios are
The magnitudes of V ₆ N−V ₆ R correspond.

(a) When V ₄ = V ₄ N Drive circuits 93l, 93r (or 94l, 9
The duty ratios of the pulse signals P ₃ l, P ₃ r (or P ₄ l, P ₄ r) emitted to the output terminals 4r) are the same.

(b) When V ₄ = V ₄ r (however, V ₄ r > V ₄ N), drive the duty ratio of the pulse signal P ₃ r (or P ₄ r) sent to the drive circuit 93r (or 94r). It is assumed that the duty ratio is smaller than the duty ratio of the pulse signal P ₃ l (or P ₄ l) being emitted to the circuit 93l (or 94l). The size of the difference between both duty ratios is
It corresponds to the magnitude of V ₄ r−V ₄ N.

(c) When V ₄ = V ₄ l (however, V ₄ l < V ₄ N) Drive the duty ratio of the pulse signal P ₃ l (or P ₄ l) that is emitted to the drive circuit 93l (or 94l) It is assumed that the duty ratio is smaller than the duty ratio of the pulse signal P ₃ r (or P ₄ r) being sent to the circuit 93r (or 94r). The size of the difference between both duty ratios is
Corresponds to the size of V ₄ N−V ₄ l.

The controller 7 determines the form of the pulse signal generated from the pulse generator 8 by combining the control modes (1) to (3) and (a) to (c) described above.

The traveling vehicle of the present invention constructed as described above is driven, shifted, braked, and steered in the following manner.

First, when the engine E is started, the hydraulic pump P is driven and pressurized oil is generated. Then, if the shift lever 5 is rotated forward from the neutral position where V ₆ = V ₆ N, and V ₆ > V ₆ N, then as shown in Fig. 3a, as described in (2) above. like V ₆ (i.e. V ₆ F) −
Pulses P ₃ l and P ₃ r with a duty ratio determined by V ₆ N are emitted to the drive circuits 93l and 93r, whereby the solenoids 13l and 13r are intermittently energized and excited. Therefore, while the solenoid valves 1l and 1r are repeatedly moving between switching positions, that is, in a chopping operation, pressure oil is supplied directly from the hydraulic pump P to the hydraulic motor Ml and via the hydraulic motor Ml. The hydraulic motor Mr rotates forward intermittently. As a result, the left and right front wheels are intermittently driven forward, and the aircraft moves forward at a speed determined by the duty ratio of the pulse signals P ₃ l and P ₃ r. If we microscopically consider the pressure oil supplied to the hydraulic motors Ml and Mr, we will see that intermittent flow occurs, but the solenoid valves 1l and 1r
Since the response is on the order of msec, the pulse generation period of the pulse signals P ₃ l and P ₃ r can be set to about 100 msec. Therefore, when considering the pressure oil supplied to the hydraulic motor from a macroscopic perspective, the unit The amount of oil flowing per hour is only limited to the product of the maximum amount of oil flowing per unit time of this hydraulic system and the duty ratio of the pulse signal, and because the aircraft is heavy, the inertia is reduced. Coupled with the large size, there is no effect on ride comfort.

Next, when the shift lever 5 is rotated further forward, the third
As shown in Figure b, the duty ratios of the pulse signals P ₃ l and P ₃ r both become large, and the proportion of time that pressure oil is supplied to the hydraulic motors Ml and Mr becomes large, causing the aircraft to accelerate. Become.

Then, when the steering wheel 3 is rotated to the right, V ₄ (=
V ₄ r) > V ₄ N, and as a result of the above (b), the duty ratio of the pulse signal P 3 r decreases as shown in Fig. 3c, and the duty ratio of the pulse signal P ₃ r decreases compared to the pressure oil supply time to the hydraulic motor Ml. Then it becomes small to the hydraulic motor Mr.
The aircraft will turn to the right. When the steering wheel 3 is rotated to the left, the duty ratio of P ₃ l becomes smaller than the duty ratio of P ₃ r, contrary to what has been described above, and the aircraft turns to the left.

When braking the traveling of the aircraft, the shift lever 5 may be returned to the neutral position. This results in a pulse signal
Since P ₃ l and P ₃ r disappear, solenoid 13l, 13
The power to r is cut off, the solenoid valves 1l and 1r switch to the neutral position, and the hydraulic motors Ml and Mr are sealed with pressure oil, and their resistance causes the hydraulic motors Ml and Mr to
Mr. So the left and right front wheels will stop again.

On the other hand, if the shift lever 5 is rotated backward from the neutral position so that V ₆ <V ₆ N, then from the point described in (3) above, V ₆ N−V ₆ (i.e., V 6 N−V 6 as shown in FIG. 3d) _V6R )
Pulses P ₄ l and P ₄ r having a duty ratio determined by are emitted to the drive circuits 94 l and 94 r, whereby the solenoids 14 l and 14 r are intermittently energized and excited. Therefore, the solenoid valves 1l and 1r are in the switching position,
The hydraulic motors Ml and Mr, which are supplied with pressure oil, are intermittently reversed during the repeated movement of . As a result, the aircraft moves backward at a speed determined by the duty ratio of the pulse signals P ₄ l and P ₄ r. When the gear shift lever 5 is rotated further backward, the duty ratios of the pulse signals P ₄ l and P ₄ r both increase, and the reverse speed is accelerated, and the steering wheel 3 is moved to the right (or left) of the steering wheel 3. As a result of the rotation operation, the duty ratio of the pulse signal P ₄ r (or P ₄ l) decreases, and the aircraft turns right (or left) while moving backward, as in the case of forward travel described above.

The controller 7 further has the following control function for the pulse generator 8. That is, the steering wheel 3
A pulse signal P ₃ r (P ₄ r when going backwards) [or P ₃ l (P ₄ l when going backwards)] is generated by turning the wheel to the right (or left).
When the duty ratio becomes 0, a pulse signal P ₄ r (P ₃ r when going in reverse) [or P ₄ l (P 3 l when going in reverse)] with a duty ratio corresponding to the amount of rotation of the steering wheel ₃ is sent. This causes the left and right front wheels to rotate in opposite directions. For example, assume that the steering wheel 3 is rotated further to the right than the state shown in FIG. 3c. Then, the duty ratio of the pulse signal P ₃ r will eventually become 0.
However, the value of V ₄ at this time is V ₄ r ₀ (V ₄ r ₀ >
V ₄ N), and the value of V ₄ when the steering wheel 3 is further rotated to the right is V ₄ re. As shown in Figure 3e, the value of V ₄ re - V ₄ r ₀ is obtained. A pulse signal P ₄ r with a determined duty ratio is issued to the drive circuit 94r. On the other hand, the pulse signal P ₃ l is sent to the drive circuit 93l.
Since is input as is, the hydraulic motor Ml,
Mr rotates forward and reverse, respectively, so that the front left wheel Fl is driven forward while the front right wheel is driven backward. Therefore, this traveling vehicle is capable of spin turns.

Next, when this traveling vehicle is towed by another vehicle, the engine E is stopped and the operating lever 2 is operated to switch the positions of the manual valves 2l and 2r, and the hydraulic motor is
Keep the inlet and outlet of Ml and Mr in communication with the oil tank. Then, motors Ml and Mr are rotationally driven as the front wheels rotate due to traction, but the motors
Since the oil in Ml and Mr flows freely, the motor Ml,
Mr rotates freely, so there is no braking on the front wheels.

As described above, the traveling vehicle according to the present invention includes one constant displacement hydraulic pump and one constant displacement hydraulic motor connected to each wheel so as to drive each of the left and right wheels independently. The hydraulic pump and each hydraulic motor are connected to each other via an electromagnetic three-position oil passage switching valve so that the oil passages are in series, and the oil passage switching valve is connected to the hydraulic motor. a first position where pressure oil is supplied to rotate the hydraulic motor in the normal direction, a second position where pressure oil is supplied to rotate the hydraulic motor in the reverse direction, or a neutral position where the oil passage on the hydraulic motor side is sealed;
In addition, it is equipped with a pulse generation circuit with a variable duty ratio of output pulses, and the output pulses are used to move each oil passage switching valve between the first position and the neutral position, or between the second position and the neutral position at high speed. Since it does not use a variable displacement hydraulic pump, it uses a fixed displacement hydraulic pump with a simple structure, so it can be provided at a low cost. There are few breakdowns. Furthermore, since a fixed displacement hydraulic pump is used to intermittently supply pressure oil to the hydraulic motor, transmission efficiency is significantly improved compared to when a variable displacement hydraulic pump is used. Continuously variable speed and steering are possible by the function of the vehicle or pulse generation circuit of the present invention.

Furthermore, when the aircraft is stopped and the gear shift lever is placed in the neutral position where the aircraft is braked, the pressure oil supply path to the hydraulic motor is completely cut off by the solenoid valve, and the pressure oil in the hydraulic motor is Since it is sealed, there is no disadvantage of micro-movement or sudden self-propulsion as seen in conventional hydraulically driven vehicles.

In order to reliably hold the neutral position, it goes without saying that a neutral position locking groove or the like is provided in the guide frame portion of the shift lever 5.

Not only does it have other advantages normally obtained when using a hydraulic drive system, such as continuously variable speed, no need for a differential, and has a braking function, but it also allows for steering and even spin turns as mentioned above. The present invention has excellent effects such as: It goes without saying that the present invention can also be applied to a crawler-type vehicle.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a left side view of a tractor according to the present invention, FIG. 2 is a hydraulic circuit diagram shown together with a block diagram of the main parts of the electric control system, and FIG. a to e are pulse signal waveform diagrams for explaining the operation. 1l, 1r...Solenoid valve, 2...Operation lever, 2
l, 2r...Manual valve, 3...Steering wheel, 5...Speed lever, 7...Controller, 8...Pulse generator, P...Hydraulic pump, Ml, Mr...Hydraulic motor.

Claims (1)

[Claims] 1. Equipped with one constant displacement hydraulic pump and one constant displacement hydraulic motor connected to each wheel so as to drive the left and right wheels independently,
The hydraulic pump and each hydraulic motor are connected to each other via an electromagnetic three-position oil passage switching valve so that the oil passages are in series, and the oil passage switching valve is
The first one supplies pressure oil to rotate the hydraulic motor in the normal direction.
position, a second position for supplying pressure oil to reverse the hydraulic motor, or a neutral position for sealing the oil passage on the hydraulic motor side, and a pulse generation circuit with a variable duty ratio of output pulses; With a pulse, each oil passage switching valve is moved between the first position and the neutral position.
Alternatively, a traveling vehicle characterized in that the second position is selectively switched between the neutral position and the neutral position at high speed.