JP3301705B2 - Paving machine wheel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wheel control device for a pavement machine such as an asphalt finisher and a repeaver / remixer.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 8-134829 discloses that a hydraulic fluid is supplied to a front wheel motor from a variable discharge type front wheel pump via a front wheel speed control electromagnetic proportional valve which operates according to the rear wheel speed. Is shown in a four-wheel drive asphalt finisher for supplying front wheel drive force.

That is, a rear wheel speed is detected by a rotational speed sensor mounted on a shaft of a sub-transmission of a rear wheel, and a wheel speed signal is thereafter transmitted to a front wheel controller (analog controller).
, And the opening degree of an electromagnetic proportional valve for controlling the front wheel speed is controlled by the front wheel controller, so that the discharge amount of the load sensing type front wheel pump is matched with the rear wheel speed.

[0004] In this case, when the discharge pressure (set relief pressure) of the front wheel pump is controlled to a constant pressure by a normal relief valve, it is difficult for the front wheels to exert a grip force (the amount of mixture in the hopper is small). If the construction surface has an excessive amount of tack coat applied or is on a soft road surface with a low adhesion coefficient, etc.), there is a problem that the front wheels may slip due to excessive driving force of the mechanical vehicle, etc. I have.

Alternatively, when the amount of mixture in the hopper is large, the front wheel is apparently locked (for example, because the pressure required to obtain the required driving force exceeds the relief pressure set for the front wheel pump). Even if the discharge pressure reaches the set relief pressure, the required driving force cannot be obtained).

In view of the above, the front wheel driving force control device disclosed in the publication discloses a manual dial for an operator to operate the front wheel pump at a portion where a front wheel load pressure is generated in a circuit for supplying hydraulic oil from the front wheel pump to the front wheel motor. An electromagnetic proportional relief valve capable of manually setting the relief pressure arbitrarily is provided.

In this conventional asphalt finisher, the operator visually observes the condition of the construction surface (a condition where the front wheels do not exert a sufficient gripping force) or the amount of mixed material in the hopper, and observes the condition of the construction surface and the hopper. Operate the manual dial based on experience according to the amount of internal mixture, and set the electromagnetic proportional relief valve to a lower pressure as the construction surface is softer, for example,
Also, the higher the amount of mixture in the hopper, the higher the pressure.

[0008]

As described above, conventionally,
The operator always visually observes the condition of the construction surface and the amount of mixture in the hopper, and empirically judges the degree of hardness and softness of the construction surface and the amount of mixture, and operates the manual dial, but the operator Such a burden is large, and an appropriate judgment is not always made.

In the conventional front wheel driving force control apparatus, the front wheel speed is controlled by operating an electromagnetic proportional valve by an analog controller according to the rear wheel speed while the machine is moving forward. Since there is no related control between the front wheels and the rear wheels, the following problems occur.

That is, in order to always secure the front wheel traction force at the time of starting the machine and to prevent the rear wheel from slipping, the current front wheel response indicated by the two-dot chain line in FIG. 3 precedes the rear wheel response indicated by the dotted line. The front wheel rotation speed is set earlier, but on the other hand, such control shifts the start timing of the front and rear wheels. Slip and the like are easy to occur.

Further, conventionally, as shown by a two-dot chain line in FIG. 3, the traction force of the front wheel is completely released at the time of stop, so that play occurs in the drive chain of the rear wheel at the time of stop, Due to the occurrence of deflection, a vehicle shock occurs at a certain point S where the front wheel response rises, not only at the time of starting but also every time the vehicle restarts, affecting the operator.

The present invention has been made in view of the above points, and can automatically change the set relief pressure of the front wheel pump according to the construction surface condition and the amount of mixed material, and can also be used when starting or stopping the machine. An object of the present invention is to provide a wheel control device of a pavement machine that can perform a related control between the front and rear wheels in a satisfactory manner.

[0013]

According to a first aspect of the present invention, there is provided a wheel control device for a pavement machine for supplying hydraulic fluid to a front wheel motor from a front wheel pump. A pressure sensor for detecting the front wheel load pressure generated in the above, a variable relief valve for variably controlling the set relief pressure of the front wheel pump in accordance with the front wheel load pressure detected by the pressure sensor, and after detecting the rear wheel speed Wheel speed sensor
And a front wheel provided between the front wheel pump and the front wheel motor.
Wheel speed control valve and the extent that the front wheel does not rotate before starting the rear wheel
Control of front wheel standby pressure for front wheel motor
After the start of the rear wheel, after being detected by the rear wheel speed sensor
During forward movement of the machine through the front wheel speed control valve in relation to the wheel speed
This is a wheel control device for a pavement machine including a digital controller that controls a front wheel speed .

The pressure relief sensor automatically detects the front wheel load pressure, which varies depending on the work surface condition and the amount of mixed material, and controls the variable relief valve, thereby reducing the set relief pressure of the front wheel pump to the work surface condition. And automatically change according to the amount of mixture . Also, the rear wheel is controlled by a digital controller.
Before starting, apply front wheel standby pressure to the front wheel motor.
By doing so, the show that occurs when the machine restarts after the machine stops
And lightly pull the front wheels before starting the machine.
Slip when starting the rear wheel is generated by applying attractive force
After starting the rear wheel, it is detected by the rear wheel speed sensor.
Forward through the front wheel speed control valve in relation to the rear wheel speed
By controlling the middle front wheel speed, the driving force
Keep the lance .

[0015] The invention described in claim 2, Contact Keru digital control to the wheel control device for paving machine according to claim 1, wherein
Drive the front wheels while the machine is moving forward at a slightly higher peripheral speed than the rear wheels.
It works .

[0016] Then, the front wheel in by Ri machinery advanced to the digital controller to drive a little at a faster peripheral speed than the rear wheels, to share a part of the running resistance of the rear wheels as the front wheels of the towing resistance.

The invention described in claim 3 is equivalent to claim 1
Or a digital controller in the wheel control device for a pavement machine according to the second aspect , performs synchronous control of a traction force rising characteristic of a front wheel and a traction force rising characteristic of a rear wheel when the machine starts.

[0018] Then, by tuning control traction rise characteristics between the front and rear wheels when the machine start by a digital controller, with obtain sufficient traction to prevent slippage between the front and rear wheels.

According to a fourth aspect of the present invention, in the wheel control device for a paving machine according to the third aspect , variable control of a set relief pressure of a front wheel pump, control of a front wheel speed during forward movement of the machine, A single digital controller performs the traction force tuning control of the front and rear wheels and the preload control of the front wheel standby pressure before starting the rear wheel.

Then, one digital controller is
The signal from the pressure sensor is processed to control the variable relief valve to change and control the set relief pressure of the front wheel pump, and to control the front wheel speed control valve in relation to the rear wheel speed detected by the rear wheel speed sensor. Control the front wheel speed while the machine is moving forward, synchronize the front wheel traction force rise characteristics and rear wheel traction force rise characteristics when starting the machine, and preload control the front wheel standby pressure to the front wheel motor before starting the rear wheels I do.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to a wheel control device for an asphalt finisher shown in FIGS.

In FIG. 1, reference numeral 11 denotes a digital controller for performing various control processes by digital signals, and includes a control panel 12 for operating the digital controller 11 and displaying a control amount. The digital controller 11 includes a central processing unit (CPU), memories (ROM and RAM), an analog / digital converter,
It is formed by a digital / analog converter or the like.

The discharge controller 15 of the rear wheel pump 14 is connected to the digital controller 11 via a discharge control line 13. This discharge amount control unit 15 is a digital controller
The discharge amount of the rear wheel pump 14 is variably controlled based on the electric signal output from 11.

The variable discharge type rear wheel pump 14 and the rear wheel motor 16 are connected by a pipe 17 to form a closed circuit. A rear wheel 19 is connected to an output shaft of the rear wheel motor 16 via an auxiliary transmission 18 capable of selecting a high / low gear ratio so as to exhibit startability. Then, the operating oil is supplied from the rear wheel pump 14 to the rear wheel motor 16 to drive the rear wheel 19.

On the shaft of the auxiliary transmission 18, a rotation detecting plate 22 is provided integrally with a rear wheel speed sensor 21 for detecting the rotational speed of the rear wheel 19. The rotation detecting plate 22 has a number of convex portions formed at a constant pitch on the outer peripheral edge, and the rear wheel speed sensor 21 (proximity sensor)
The amount of rotation (rotational speed) of the rear wheel 19 per unit time is detected by inputting a pulse signal generated by detecting each convex portion of the rotation detection plate 22 to the digital controller 11 through a signal input line 23.

On the other hand, the front wheel pump 31 is provided with a discharge amount control unit 32 for variably controlling the pump discharge amount.
The variable discharge rate front wheel pump 31 has a discharge line
33 is connected to an inlet port of an electromagnetic proportional valve for front wheel speed control (hereinafter, referred to as front wheel speed control valve 34). The front wheel speed control valve 34 is an electromagnetic valve that operates in proportion to an electric signal (current) supplied from the digital controller 11 to the solenoid 34a in relation to the rear wheel speed detected by the rear wheel speed sensor 21.

A pair of front wheel motors for driving left and right front wheels 35 are provided at one outlet port of the front wheel speed control valve 34.
One port of the front wheel motor 36 is connected in parallel, the other port of each front wheel motor 36 is connected to the other outlet port of the front wheel speed control valve 34, and the drain port of the front wheel speed control valve 34 is connected to the tank 37.
Communicate with

Further, the front wheel speed control valve 34 and the front wheel motor
By drawing a pilot line 41 from the pipeline between the front wheel pump 36 and the discharge line control unit 32 of the front wheel pump 31, the front wheel load pressure generated in the forward circuit of the front wheel motor 36 is reduced by the front wheel pump 31. This is fed back to the discharge amount control unit 32. The discharge amount control unit 32 controls the front wheel pump 31
The pump discharge rate is variably adjusted in accordance with the front wheel load pressure generated in the pipeline supplying hydraulic oil to the forward port 36.

In the pilot line 41, a pressure sensor 42 for detecting a front wheel load pressure is provided as a sensor for detecting a condition of a construction surface (a condition which influences a grip force of the front wheel 35) and a degree of a mixture amount in the hopper. The signal acquisition line 43 of the pressure sensor 42 is connected to the input terminal of the digital controller 11.

Further, a relief line 44 is drawn out from the pilot line 41, and a variable relief valve 45 for variably controlling the set relief pressure of the front wheel pump 31 is provided. The variable relief valve 45 is an electromagnetic proportional relief valve that variably controls the set relief pressure of the front wheel pump 31 in accordance with the front wheel load pressure signal detected by the pressure sensor 42, and outputs an output signal to the output terminal of the digital controller 11. The set relief pressure of the hydraulic oil supplied to the front wheel motor 36 is controlled by the current value supplied to the solenoid 45a connected via the line 46.

The digital controller 11 is a common controller for the front wheels and the rear wheels. The one digital controller 11 controls the front wheel load as a construction surface condition signal detected by the pressure sensor 42 or a mixed material amount detection signal. The set relief pressure of the variable relief valve 45 is variably controlled in accordance with the pressure signal, and the front wheel speed control valve 34 is controlled in relation to the rear wheel speed detected by the rear wheel speed sensor 21 to control the front wheels during machine advance. The speed is controlled, and the traction force rise characteristic by the rear wheel motor 16 and the traction force rise characteristic by the front wheel motor 36 at the time of starting the machine are tuned and controlled. Each program has a program for performing preload control of the pressure to the front wheel motor 36. These control methods will be described in detail in the following operation description.

Next, the operation of the illustrated embodiment will be described.

While the machine is moving forward, the rotation of the front wheel while the machine is moving forward is controlled through the front wheel speed control valve 34 in relation to the rear wheel speed (hereinafter referred to as the rear wheel speed) detected by the digital controller 11 by the rear wheel speed sensor 21. Speed (hereinafter referred to as front wheel speed), for example, driving the front wheel 35 during machine advance at a peripheral speed slightly higher than the rear wheel 19, and reducing a part of the running resistance of the rear wheel 19 to the front wheel.
35 traction resistance.

The reason why the front wheel 35 is driven at a peripheral speed slightly higher than that of the rear wheel 19 will be further described. When the front wheel speed is lower than the rear wheel speed, the rotation of the front wheel 35 as viewed from the rear wheel 19 reduces the traction resistance. Since it works in the increasing direction, the performance of front and rear wheel drive (four-wheel drive or six-wheel drive) is impaired. Therefore, the front wheel speed is always higher than the rear wheel speed detected by the rear wheel speed sensor 21 in consideration of variations in valve flow rate due to oil temperature change, changes in motor volumetric efficiency, rear wheel tire pressure, etc. By controlling the opening of the front wheel speed control valve (electromagnetic proportional valve) 34 by the digital controller 11 so that the front wheel 35 pulls the rear wheel 19 by the pump relief pressure, the front wheel pump 31 Is controlled.

At this time, it is necessary to control so that idling (runaway rotation due to insufficient gripping force of the front wheel 35) due to excessive flow rate on the front wheel side is performed. Therefore, load sensing is performed so as to maintain a pressure corresponding to the front wheel load pressure. The pump flow rate from the front wheel pump 31 of the mold is controlled to synchronize the speed, and the front wheel side is set slightly faster so that the rotational speed difference between the front and rear wheels is always small. As described above, basically, the front and rear wheels are rotated at the same speed, but for the above-described reason, it is microscopically necessary to send a flow rate command to the front wheel side more slightly to make the rotation speed slightly higher than that of the rear wheel 19. desirable.

During the forward movement of the machine, the front wheel load pressure is detected by the pressure sensor 42, and the condition of the construction surface (the condition in which the front wheel 35 is hard to exert the gripping force) and the amount of mixed material in the hopper are automatically and comprehensively measured. Judgment is made.

For example, when the amount of the mixture in the hopper is small, or when the front wheel 35 is approaching a construction surface with an excessive amount of tack coat applied or a weak construction surface with a low adhesion coefficient, the front wheel
Since the grip force of the front wheel 35 decreases and the front wheel load pressure generated according to the load of the front wheel motor 36 also decreases, the digital controller 11 immediately reads the change with the pressure sensor 42 and The set relief pressure is automatically and continuously changed to the low pressure side according to the construction surface conditions and the amount of mixed material.

As a result, the set relief pressure of the front wheel pump 31 decreases, and the front wheel operating pressure supplied to the front wheel motor 36 also decreases, so that the front wheel driving force decreases to a level corresponding to the front wheel gripping force. Prevent the occurrence of slip due to excessive driving force and prevent excavation of the construction surface.

At the same time, the control pressure fed back to the discharge amount control unit 32 of the front wheel pump 31 by the pilot line 41 is automatically reduced according to the construction surface condition and the mixed material amount. The discharge amount is also reduced, and it is possible to cope with a decrease in the flow rate required on the motor side, and it is possible to increase pump efficiency.

On the other hand, the load applied to the front wheel 35 changes according to the amount of the mixture in the hopper located above the front wheel 35, and accordingly, the upper limit of the driving force that can be generated in a range where the front wheel 35 does not slip. Digital controller 11
Reads the change of the front wheel load pressure by the pressure sensor 42 and automatically changes the set relief pressure of the variable relief valve 45 in accordance with the amount of mixture in the hopper.

For example, when the road surface condition is constant and the amount of mixture in the hopper is small, the upper limit of the driving force that can be generated in a range where the front wheels 35 do not slip is reduced. Read the change,
The setting relief pressure of the variable relief valve 45 is automatically changed to the low pressure side. As a result, the upper limit of the front wheel operating pressure supplied to the front wheel motor 36 also decreases, so that the driving force of the front wheel 35 decreases, and the maximum driving force that does not cause the front wheel 35 to slip can be obtained.

Conversely, when the road surface condition is constant and the amount of mixture in the hopper is large, the upper limit of the driving force that can be generated in a range where the front wheels 35 do not slip increases, so that the digital controller
11 is a variable relief valve 45 according to a command programmed in the memory (ROM) of the controller in advance.
The setting relief pressure is automatically changed to the high pressure side. As a result, the upper limit of the front wheel operating pressure supplied to the front wheel motor 36 also increases, so that the driving force of the front wheel 35 increases, and it is possible to generate the upper limit of the set relief pressure and within a range where the front wheel 35 does not slip. Driving force is obtained.

Next, FIG. 2 shows that the digital controller 11 uses the digital controller 11 to increase the traction force of the front wheel 35 and the rear wheel 19 when the machine starts.
An example is shown in which the traction force rising characteristic is controlled in synchronization.

That is, the digital controller 11 adjusts the discharge amount control unit 15 of the rear wheel pump 14 to adjust the rear wheel motor.
By controlling the discharge amount to the front wheel motor 36 by controlling the discharge amount to the front wheel motor 36 by controlling the front wheel speed control valve 34, the tuning control is performed so that the start timings of the front and rear wheels coincide as shown in FIG. I do.

When such tuning control is performed, the rear wheel
It is possible to simultaneously raise the driving force of both the 19 and the front wheel 35, thereby preventing a shortage of the tractive force due to imbalance and obtaining a sufficient tractive force, and also preventing the occurrence of slip between the front and rear wheels.

Next, FIG. 3 shows another control example partially utilizing the tuning control shown in FIG.
When a forward command of the machine is issued, a control signal is output to the front wheel speed control valve 34 before the discharge amount from the rear wheel pump 14 is controlled and the rear wheel motor 16 is started, so that the front wheel pump 31
Is supplied to the front wheel motor 36 to cause the front wheel 35 to increase the traction force as shown in the part A.

The supply pressure to the front wheel motor 36 before the start of the rear wheels is a front wheel standby pressure set to a low pressure as shown in the part B. The front wheel standby pressure always causes the front wheels 35 to pull the mechanical vehicle. Is low enough to generate traction, but not high enough to generate traction enough to rotate the front wheel 35 alone.

As described above, by preload-controlling the front-wheel standby pressure to the front-wheel motor 36 before starting the machine and applying a light traction force to the front wheel 35, the occurrence of slip when the rear wheel 19 starts is prevented. I do.

Then, the front and rear wheels at the time of mechanical start are synchronized and controlled by the digital controller 11 as shown in section C, thereby obtaining a sufficient traction force and preventing the occurrence of slip between the front and rear wheels.

Further, even after the machine is stopped and before the rear wheel motor 16 is started, a front wheel standby pressure that does not lead to the rotation of the front wheel is applied to the front wheel motor 36 by the digital controller 11 as shown in part D. By giving it,
It is possible to reliably prevent the shock that occurs in the mechanical vehicle at the time of restarting due to the play of the rear wheel drive chain and the occurrence of tire deflection while the machine is stopped, and to apply a light traction force to the front wheel 35 in advance before starting Prevents the occurrence of slip when starting the rear wheels.

Thus, the shock generated in the mechanical vehicle can be suppressed only by the front wheel standby pressure control when the standby pressure rises at the time of the initial start of the portion A, and the occurrence of the shock at the time of the subsequent restart can be prevented. . If the front wheel standby pressure control is not performed, point S
Shock occurs.

As described above, the detection of the rear wheel speed and the detection of the front wheel load pressure are performed by using one digital controller 11, and the signal of the detected front wheel load pressure is transmitted to the variable relief valve (electromagnetic proportional relief valve). Valve) 45 and the system that controls the set relief pressure of the front wheel pump 31 based on the feedback value allows automatic adjustment of the front wheel load pressure in real time according to the conditions of the construction surface and the amount of mixture in the hopper. Take control.

Further, since the two circuits of the rear wheel circuit and the front wheel circuit can be controlled in cooperation using one digital controller 11, the rear wheel motor 16 can be used when the mechanical vehicle starts or stops.
And the front wheel motor 36 (the synchronous control of vehicle start or the front wheel standby control based on the synchronized front and rear wheel rise timing) can be properly performed, and the front wheel speed control valve (electromagnetic Adjustment of the input current value to the proportional valve 34 can be automated.

[0054]

According to the first aspect of the present invention, the variable relief valve is controlled by the front wheel load pressure detected by the pressure sensor, and the set relief pressure of the front wheel pump is adjusted according to the construction surface condition and the mixed material amount. Automatically changes the power, automatically preventing excavation of the construction surface due to excessive front wheel driving force and shortage of front wheel driving force, reducing the burden on the operator and preventing erroneous operations relying on the operator's experience. Can be prevented. Further, automation can be effectively achieved using an inexpensive pressure sensor . Sa
In addition, the digital controller uses the front wheels before starting the rear wheels.
Front wheel stabilization that does not lead to front wheel rotation
By restarting the machine after stopping by controlling the preload
Shocks that occur during
By applying light traction to the front wheels before going forward
Prevents occurrence of slip when starting the rear wheel, construction with rear wheel
Surface excavation can be prevented, and the rear wheel speed sensor
Through the front wheel speed control valve in relation to the detected rear wheel speed.
Automatically control the front wheel speed while the machine is moving forward.
Therefore, the driving force balance between the front and rear wheels can be maintained .

According to the second aspect of the present invention, a part of the running resistance of the rear wheels is used as the traction resistance of the front wheels by driving the front wheels during mechanical advancement at a peripheral speed slightly faster than the rear wheels by the digital controller . Sharing the driving force balance between the front and rear wheels can be maintained optimally.

According to the third aspect of the present invention, by controlling the rise of the traction force between the front and rear wheels at the time of mechanical start by the digital controller in synchronization, sufficient traction force can be obtained and slip between the front and rear wheels can be generated. to prevent, kill at preventing the cause excavation of the construction surface.

According to the fourth aspect of the present invention, a single digital controller can be used to variably control the set relief pressure of the front wheel pump, control the front wheel speed during forward movement of the machine, control the front and rear wheels to synchronize the front and rear wheels when starting the machine, By comprehensively performing the preload control of the front wheel standby pressure before the rear wheel is started, it is possible to perform optimal control during stoppage of the machine, at the time of starting, and during forward movement.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a wheel control device for a pavement machine according to the present invention.

FIG. 2 is a traction force / time characteristic diagram of a front wheel and a rear wheel showing an example of front and rear wheel tuning control by a digital controller of the control device.

FIG. 3 is a traction force / time characteristic diagram of front wheels and rear wheels showing an example of front wheel standby control and front and rear wheel tuning control by the digital controller.

[Explanation of symbols]

11 digital controller 19 rear wheel 21 rear wheel speed sensor 31 for the front wheels pump 34 the front wheel speed control valve 35 wheel 36 wheel for motor 42 a pressure sensor 45 deformable relief valve

Continuation of the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) E01C 19/22 E01C 19/48 E01C 23/00 B60K 17/10 B60K 28/16 F02D 29/02 311 F02D 29/02 321 F02D 45/00 345

Claims (4)

(57) [Claims] 1. A wheel control device for a pavement machine for supplying hydraulic fluid to a front wheel motor from a front wheel pump, comprising: a pressure sensor for detecting a front wheel load pressure generated between the front wheel pump and the front wheel motor; of the deformable relief valve for variably controlling the set relief pressure of the front wheel pump according to the front wheel load pressure detected by the pressure sensor, a wheel speed sensor after detecting a rear wheel speed, front wheel pump and front wheel drive motor Front wheel speed provided between
Degree control valve and front wheel standby that does not lead to front wheel rotation before starting the rear wheel
Preload control for front wheel motor and rear wheel start
After that, in relation to the rear wheel speed detected by the rear wheel speed sensor
Control the front wheel speed while the machine is moving forward through the front wheel speed control valve
A wheel control device for a pavement machine, comprising: a digital controller . 2. The wheel control device for a pavement machine according to claim 1 , wherein the digital controller drives the front wheels while the machine is moving forward at a peripheral speed slightly faster than the rear wheels . 3. A digital controller according to claim 1, characterized in that tuning control the traction force rising characteristics of the front wheel traction rise characteristics and the rear wheels when the machine start or
3. A wheel control device for a paving machine according to claim 2. 4. A variable control of a set relief pressure of a front wheel pump, a control of a front wheel speed during forward movement of a machine, a tuning control of front and rear wheels at the time of starting a machine, and a preload control of a front wheel standby pressure before starting a rear wheel are performed by one The wheel control device for a paving machine according to claim 3, wherein the control is performed by a digital controller.