JPS59184037A - Drum-driving device for mixer truck - Google Patents

Abstract

PURPOSE:To obtain stable running of a mixer truck by providing a servo-motor by detecting a low-speed position of a speed change gear by a position detector to bring a variable capacity type liquid-pressure pump to a neutral position for stopping a drum automatically when the mixer truck is started or driven on a steep slope. CONSTITUTION:When a speed change lever 4a is thrown in the first speed at the time of starting or driving on a steep slope, a limit switch 19 is on to move a switch valve 15 to a position A. Thereby, the pressure liquid from an auxiliary pump 13 to a servo-motor 14 is drained to make the servo-motor 14 free from the work of the pressure liquid. Consequently, a piston device 16 of the servo- motor is automatically returned to a neutral position by the work of springs 16a and 16b without reference to the operational position of an operation lever 18. Then, the liquid-pressure pump 6 is operated at the neutral position, and the pressure liquid is not supplied to a liquid-pressure motor 7 to stop a drum. When a speed-change lever 4a is switched over to a high-speed position, the drum can be operated for normal rotation. This construction permits to prevent an operator from operating a mixer truck erroneously.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drum drive device for a mixer truck using a hydraulic circuit that combines a variable displacement hydraulic pump and a hydraulic motor.

As is well known, the drum drive device of the mixer truck transmits a part of the power of the engine from the running engine of the mixer truck to the variable capacity mother type hydraulic pump via, for example, a power take-off device, and uses the pressure from the hydraulic pump. The liquid drives a hydraulic motor, which rotates the drum.

FIG. 1 is an explanatory diagram showing an example of a drum drive device for such a known Migi υ-vehicle. is transmitted via the clutch 3 to a gear shift state 4 operated by a gear shift lever 4a. The rotational force from the output shaft 41) of this transmission 4 is
10 and a stop gear device 11 to rotate the rear wheel 12 of the truck. On the other hand, the output from the power extraction device 2 is configured to rotate a variable displacement hydraulic pump 6 (hereinafter simply referred to as a hydraulic pump) via a drive shaft 5. The hydraulic pump 6 is connected to the main lines Lz and L2 (one of which is a discharge run,
The other end is a return line) and is connected to a liquid juice motor 7 d3, which is configured to rotate a drum 9 via a speed reducer 8.

Since the mixer drum is normally driven constantly, a portion of the engine output is necessarily consumed as the rotational energy of the hydraulic pump, and therefore the rotational energy of the traveling device, that is, the wheels 12, is consumed by the hydraulic pump. or less. Therefore, especially when starting on a steep slope, the maximum output must be given to the wheels 12. At that time, the driver controls the tilting angle device of the hydraulic pump 6 to reduce the discharge amount to zero, thereby reducing the Migisa drum. It becomes necessary to stop it. When the mixer truck is traveling over a long distance on a steep slope, the discharge amount of the hydraulic pump is often reduced to zero in order to prevent the mixer truck from shaking due to the rotation of the mixer drum. In order to control the hydraulic pump in this way, the conventional device shown in Figure 1 requires manual operation, which is very complicated, and especially in the case of manual operation, even the slightest movement of the manual lever can cause the drum to be erroneously moved to the reverse side. Then, the ready-mixed concrete is discharged. In addition, when such operations are generally required, 1, /
Drivers often have to perform various operations such as gear shifting, steering wheel operation, and clutch operation. It is very difficult to confirm that it is in position. Since the driver's attention is inevitably focused on driving operations, the operation of the hydraulic pump becomes secondary, which tends to cause unexpected accidents such as reversing the drum.

Therefore, the V:l object of the present invention is to automatically set the hydraulic pump to the neutral position when the mixer truck starts or climbs a steep slope, thereby preventing driver's erroneous operation. We provide equipment for purchase.

According to the present invention, a position detector is provided for detecting the low gear position of the transmission of the mixer truck, and a servo motor is provided for moving the variable displacement hydraulic pump to the neutral position in response to a signal from the position detector. be.

Therefore, when the driver starts or climbs a steep hill,
1 in the low gear position! ! When the pump is turned on, the servo motor automatically puts the hydraulic pump in the neutral position, so that the hydraulic pressure d[pump's discharge amount becomes small and the drum no longer rotates. Therefore, a situation where the drum is rotated in the opposite direction does not occur.

In implementing the present invention, it is important to determine the low gear position of the transmission (which usually means first gear. However, in some cases,
Position detectors can also be provided in the second and third gears. Further, it is preferable that the signal from the position detector switches the switching valve so that the servo motor is placed in the neutral position.

In carrying out the present invention, the present invention will be described in detail with reference to FIG. 2, in which parts corresponding to those in FIG. 1 are designated by the same reference numerals. The driving force of the engine 1 is transmitted to the hydraulic pump 6 via the power take-off device shown in FIG. It drives the pressure motor 7. In the illustrated example, this hydraulic circuit is constructed as an open circuit and is provided with a safety valve and means for supplying and discharging liquid d3 in a known manner, but this is not the gist of the invention. Since there is no direct relationship, the explanation will be omitted.

An auxiliary pump 13 is provided to be driven together with the hydraulic pump 6, and liquid discharged from the auxiliary pump 13 is sent to the servo motor 4 via a line L3. A switching valve 15 is installed in this line L3. The servo motor 4 is known per se, and includes a piston device 16 for changing the tilting angle of the hydraulic pump 6 and an operation valve 17, and the piston device 16 has springs 16a and 16b when no pressure fluid is applied. By operating the control lever 18, the operation valve 17 supplies pressure fluid to the piston device 16 and changes the tilt angle of the hydraulic pump G. There is.

A position detector such as a limit switch '19 is provided which is turned on when the gear shift lever 4a is placed in a low gear position, that is, in the illustrated embodiment, in the first gear position. When one limit switch is turned on, the switching valve 6 is switched from position (a) to position (b).

During normal driving, the shift lever 4a of the Mikina car is not in the low gear position but in the ρ11th gear, so the limit switch 19 is off, and therefore the switching valve 1 is not in the low gear position.
5 is located at position (A) as shown in the figure.

Therefore, by operating the operating lever 1B, the hydraulic pump 61. is driven. For example, when the shift lever 4a is set to the first gear when starting or climbing a steep hill, the limit switch 19 is turned on and the selector valve 15 is in position (B).
move to. Then, the auxiliary pump 13 reaches the servo motor 14.
Since the pressure liquid from the pump is drained, no pressure waves act on the Seabo motor 14. Therefore, the operating position of the operating lever 18 is 1! Regardless of u, the piston device 16 of the nervous motor automatically returns to the neutral position by the action of the spools 16a and 16b, and therefore the hydraulic pump 2 is operated in the neutral position, so that no pressure fluid is applied to the hydraulic motor 7.

Therefore, the drum stops. Then, by switching the speed change lever 4a to the high speed position, normal drum rotation operation can be performed.

As described above, according to the present invention, when the gear shift lever is shifted to a low gear position (for example, 1st gear) when starting or climbing a steep slope, the discharge amount of the hydraulic pump automatically becomes zero. , there is no load on the drum drive. Therefore, when the mixer truck is running at low speed, the full power of the engine can be transmitted to the running wheels, and the mixer truck accelerates.
Improves sex.

Therefore, when the MIKI IJ car is running normally at high speed, it is difficult to rotate the MIKI IJ drum at the desired rotation speed.

However, the present invention automatically reduces the power consumption of the hydraulic pump to substantially zero when the Mikina truck needs to transmit high power to the platform, that is, the wheels, on which it runs at low speeds. Since the 1ζ ram can be prevented from rotating, the maximum output of the engine can be transmitted to the wheels1. Also, since the drum automatically stops on steep slopes, the movement of the Miki 1ner car can be prevented. can be prevented and driving safety can be improved. Since this operation is automatic,
There is no need for manual operation, so there is no possibility of erroneous operation.

In carrying out the present invention, a limit switch may be provided to cancel the signal from the limit switch, so that the rotation of the drum may be avoided as in the prior art, regardless of the position of the gear shift lever of the transmission.

For example, if a limit switch is provided only at the first gear position of the gear shift lever, a delay means, such as an electric It is preferable to use a delay relay provided in the circuit or a throttle provided in the control pressure supply boat of the servo motor. By doing this, the start timing of the drum is delayed, the start shift of the drum is prevented, and the wheels are moved by the delay time. lJ
Supply J power C cut.

[Brief explanation of drawings]

Figure 1 shows the drum Iu dynamic%M' of a conventional mixer truck.
An explanatory diagram showing yIt, and FIG. 2 is an explanatory diagram of a drum drive equipment of a mixer truck in which the present invention is implemented. 1... Engine 4a... Speed change lever 6... Variable displacement hydraulic pump 7... Hydraulic motor 9...
・Drum 14...Servo motor 15...Switching valve 19...Limit switch

Claims (1)

[Claims] In a drum drive device for a mixer truck using a hydraulic circuit using a variable displacement hydraulic pump and a hydraulic motor, a position detector is provided to detect the low gear position of the transmission of the mixer truck. A drum drive/drive device for a mixer truck, characterized in that it is equipped with a single-stroke motor that can set a variable displacement hydraulic pump to a neutral position in response to a signal from the pump.