JPS606341Y2 - Speed control device for snowplows, etc. - Google Patents

Description

[Detailed description of the invention] This invention relates to a speed control device that is suitable for use in snowplows and the like that use a single engine to drive a blower and a traveling hydraulic motor, and perform work using the blower while traveling. be.

In general, a snowplow has a structure in which a single engine operates a snow removal device such as a hydraulic pump and a blower, and a hydraulic motor, which is rotated by the hydraulic pump, moves at a very low speed while operating the snow removal device to remove snow. It has become.

Therefore, in order to increase the work efficiency of this snowplow, it is necessary to change the work speed according to the load conditions, but this is actually quite difficult, and in the pursuit of improving efficiency, it is impossible to overload the vehicle. Many years of experience, advanced technology, and careful attention are required, as this can lead to various troubles due to overloaded operation, or can lead to a loss of efficiency due to overloaded operation.

This invention was made in view of the above points, and an object of the present invention is to provide a speed control device configured so that the working speed is automatically changed according to load conditions.

This invention will be described in detail below with reference to the drawings.

The drawing shows an embodiment of this invention applied to a snowplow, and numeral 1 in the drawing is a variable displacement hydraulic pump.

This hydraulic pump 1 is connected to a snow removal device (not shown) such as a blower or an auger by a drive device (not shown) such as an internal combustion engine.
It includes a charging pump 2, a servo cylinder 3 operated by the charging pump 2, and a control valve 9 for switching the direction and amount of pressure oil sent out from the hydraulic pump 1.

A constant displacement hydraulic motor 6 is connected to the hydraulic pump 1 via hydraulic circuits 4 and 5.

The hydraulic motor 6 is rotatably driven by pressure oil sent from the hydraulic pump 1, and serves as a driving source for a traveling device (not shown).

The control circuit 7 for the servo cylinder 3 by the charging pump 2 is provided with a brake solenoid valve 8 and a control valve 9 connected to a brake light switch (not shown).
When the brake is depressed and the brake light switch is turned on, the brake solenoid valve 8 is activated and the oil supply function of the hydraulic pump 1 is stopped, and when the control valve 9 is operated, the oil supply function of the hydraulic pump 1 is stopped as described above. It is configured so that the direction and amount of oil fed can be switched in response to the operation.

In the speed control device of this invention, the hydraulic circuit 4,
5 is provided with a bypass circuit 10, and this bypass circuit 10 is provided with an electromagnetic flow rate adjustment valve 11.

This electromagnetic flow rate adjustment valve 11 is opened by a control means described later to allow pressure oil to flow through the bypass circuit 10, and the hydraulic motor 6
Decrease the rotation speed.

The above-mentioned control means of the electromagnetic flow rate adjustment valve 11 include a low rotation motion detector 12 and a high rotation motion detector 13.
and a relay 14.

The low rotation motion detector 12 detects the rotation of the rotary disk 15 rotated by the drive device using a first detection means 16 such as a proximity switch or a phototube, and detects when the rotation speed reaches a predetermined low rotation speed or less. It is configured to turn on when , and turn off when this is exceeded, and is incorporated in one electric circuit 17 in series with relay 14 .

Further, the high-speed motion detector 13 includes the rotary disk 1
5 is detected by a second detection means 18 such as a proximity switch or a phototube.
It is configured to turn on when the rotational speed is below a predetermined high rotational speed, and turn off when it exceeds this, and is not incorporated into other electrical circuits 19. It is.

Here, the meanings of low rotation and high rotation of the motion detectors 12 and 13 are merely comparative, and only mean that the set rotational speed of the low rotation motion detector 12 is set lower than that of the high rotation motion detector 13. do not have.

Furthermore, the relay 14 includes a self-holding relay contact 2o that is installed in series with the high-speed motion detector 13 in the electric circuit 19, and a self-holding relay contact 2o that is installed in the electric circuit 21 of the electromagnetic flow rate adjustment valve 11 together with the electromagnetic flow rate adjustment valve 11. It has a relay contact 22 incorporated in series, and is configured so that when the relay 14 is turned on, the relay contact 20.22 is also turned on.

Further, the relay 14 is connected to a relay contact 20 via an electric circuit 19 connected to an electric circuit 17, and when the high rotation motion detector 13 is in the ON state,
The ON state is maintained by the relay contact 20.

23 is a main switch, and 24 is a constant voltage device, which are provided to ensure stable operation of the motion detectors 12 and 13.

25 is a capacitor.

Note that the motion detectors 12 and 13 usually have a variable structure in which the set rotational speed can be arbitrarily changed.

Next, the operation of the speed control device according to the invention constructed as described above will be explained.

First, the drive device is started and the main switch 23 is turned on.

The rotational speed of the drive device is determined by motion detector 12.13.
detecting means 16.18 detects that the rotational speed of the drive is low due to overload.
2, the low rotation motion detector 12 is turned on and the relay 14 is turned on to close the relay contact 22.

Therefore, the electromagnetic flow rate adjustment valve 11 is opened and a portion of the pressure oil sent from the hydraulic pump 1 to the hydraulic motor 6 is released to the bypass circuit 10, so that the rotational speed of the hydraulic motor 6 is automatically reduced.

As a result, the load on the driving system of the snowplow is reduced, and a corresponding amount of driving force is applied to the snowplow system.

In this case, the high-speed motion detector 13 and the self-holding relay contact 20 are also turned on, but as will be described later, they are only working latently, and have no substantial effect.

In the above state, the rotational speed of the drive device is increased in connection with the load reduction, and when the rotational speed exceeds the rotational speed set in the low rotational motion detector 12, the low rotational motion detector 12 is turned off, but as described above, The high-speed motion detector 13 and self-holding relay contact 20 are turned ON.
, and the relay 14 is self-holding, so the above state continues as it is.

In this way, when the rotation speed of the drive device increases further and exceeds the rotation speed set in the high rotation motion detector 13, the high rotation motion detector 13 is turned OFF and the relay 14 is turned OFF, so that the relay contact 22 is opened. .

Therefore, the electromagnetic flow rate adjustment valve 11 closes and the bypass circuit 10
Since the hydraulic motor 6 is closed, the hydraulic motor 6 rotates normally without being decelerated, increasing the running speed of the snowplow.

If the above state becomes overloaded again and the rotation of the drive device decreases and becomes lower than the rotation speed set in the low rotation motion detector 12, the low rotation motion detector 1
2 is turned on, the relay 14 is activated, and the electromagnetic flow rate adjustment valve 11 is opened to reduce the rotational speed of the hydraulic motor 6.

By the way, although the case of a snowplow has been described so far, the speed control device of this invention can be implemented not only in a snowplow but also in various types of work vehicles and other work equipment.

As mentioned above, the speed control device according to this invention automatically lowers the rotational speed of the hydraulic motor 6 to reduce the load when an overload condition occurs, and also lowers the load to create some leeway in the driving force. Since the rotational speed of the hydraulic motor 6 automatically increases when the load increases, anyone can work efficiently without having long experience or advanced technology, and it also eliminates the problem of overload. It has the advantage of being able to prevent various problems that may occur.

[Brief explanation of drawings]

The drawings show an embodiment of the speed control device of this invention. Fig. 1 is a hydraulic circuit diagram of a hydraulic pump and a hydraulic motor, and Fig. 2
The figure is a control electrical circuit diagram of the electromagnetic flow rate regulating valve. 1... Hydraulic pump, 4, 5... Hydraulic circuit, 6... Hydraulic motor, 10... Bypass circuit, 11... Electromagnetic Flow rate adjustment valve, 12...
...Low rotation motion detector, 13...
・High rotation motion detector, 14... Relay, 17... Electric circuit, 19... Electric circuit, 20... Self-holding relay contact, 21...
...Electric circuit, 22...Relay contact.

Claims (1)

[Scope of utility model registration request] A bypass circuit 10 provided in the hydraulic circuits 4 and 5 that connects a hydraulic motor 6 to a hydraulic pump 1 operated by a drive device, an electromagnetic flow rate adjustment valve 11 provided in this bypass circuit 10, and a rotation of the drive device. Low rotation motion detector 1 that turns ON when the speed is below a predetermined low rotation speed and turns OFF when it exceeds this value.
2, a high rotation motion detector 13 which is connected to the low rotation motion detector 12 and which is connected to the low rotation motion detector 12 and turns on when the rotation speed of the drive device is below a predetermined high rotation speed, and turns off when it exceeds this. A relay 14 that is turned on when the rotational motion detector 12 is turned on is connected to the electromagnetic flow regulating valve 11, and is closed when the relay 14 is turned on to open the electromagnetic flow regulating valve 11. A first relay contact 22 that is opened when the relay 14 is turned off and closes the electromagnetic flow control valve 11 is connected to the high-speed motion detector 13 and the relay 14, and the high-speed motion detector 13 is in the ON state. A second relay contact 20 is provided, which maintains the closed state at times to cause the relay 14 to self-maintain the ON state, and is opened to turn off the relay 14 when the high-speed motion detector 13 is turned off. A speed control device for snowplows, etc., characterized by: