JPH06265014A - Hydraulic closed circuit device and method of shifting gears - Google Patents

Abstract

(57) [Abstract] [Purpose] The volumetric efficiency of the entire device is improved by eliminating the leak between the main pipes when the variable displacement hydraulic motor is in the non-operating state. [Structure] Double tilting hydraulic pump 2 and this hydraulic pump 2
And a plurality of hydraulic motors 5 and 9 which are connected in a closed circuit by a pair of main pipes 3 and 4, and at least one hydraulic motor 9 of the plurality of hydraulic motors is of a variable displacement type. The hydraulic closed circuit device in which the output shafts 5a and 9a are commonly connected is provided with an electromagnetic switching valve 8 that connects and disconnects the input / output port of the variable displacement hydraulic motor 9 to and from the pair of main pipes 3 and 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic closed circuit in which a plurality of hydraulic motors are connected to a two-tilt type hydraulic pump in a closed circuit by a pair of main pipe lines, and output shafts of the plurality of hydraulic motors are commonly connected. Regarding the device.

[0002]

2. Description of the Related Art A hydraulic closed circuit device of this type is disclosed in Japanese Patent Laid-Open No.
The device disclosed in Japanese Patent Publication No. 2404042 is known. FIG. 4 is a diagram showing this conventional hydraulic closed circuit device. The closed circuit device shown here is a fixed displacement hydraulic motor M1 with a pair of main pipelines ML1 and ML2 in a bi-tilt type hydraulic pump P.
And the variable displacement hydraulic motor M2 are connected in a closed circuit, and the output shafts SH1 and SH2 of the hydraulic motors M1 and M2 are connected to the output shaft S via the intermediate gears IG1 and IG2 and the clutch CL.
It is commonly connected to H.

In order to maximize the gear ratio (output torque of the output shaft SH), the displacement volume of the variable displacement hydraulic motor M2 is set to the maximum value, and the clutch CL connects the output shafts of a pair of hydraulic motors. Keep it. When the gear ratio is set to the minimum (the rotation speed of the output shaft SH is set to the highest speed), the displacement volume of the variable displacement hydraulic motor M2 is set to zero and the output shaft of the variable displacement hydraulic motor M2 is set by the clutch CL. SH2 is separated from the output shaft SH1 of the hydraulic motor M1.

[0004]

However, in such a conventional closed circuit device, input / output is performed when the displacement volume of the variable displacement hydraulic motor M2 is set to zero (in the non-operating state). There is a leak between the ports, and pressure oil leaks from the high-pressure side main pipe to the low-pressure side main pipe, which reduces the volumetric efficiency of the entire device.

An object of the present invention is to provide a hydraulic closed circuit device which improves the volumetric efficiency of the entire device by eliminating the leak between the main pipes when the variable displacement hydraulic motor is in the inoperative state. It is in.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. 1 showing an embodiment.
And a plurality of hydraulic motors 5 and 9 which are closed circuit-connected to the hydraulic pump 2 by a pair of main pipes 3 and 4, and at least one hydraulic motor 9 of the plurality of hydraulic motors is of a variable displacement type. It is applied to a hydraulic closed circuit device in which the output shafts 5a and 9a of the hydraulic motors 5 and 9 are commonly connected. The above-mentioned object is to connect and disconnect the input / output port of the variable displacement hydraulic motor 9 to and from the pair of main pipe lines 3 and 4.
This is achieved by a hydraulic closed circuit device provided with. In the hydraulic closed circuit device according to the second aspect, as shown in FIG. 2, the output shafts 5a, 9a of the plurality of hydraulic motors 5, 9 are connected via a clutch 15. In the hydraulic closed circuit device according to claim 3, the variable displacement hydraulic motor 9 is an oblique shaft hydraulic motor having a sector type valve plate structure, and the minimum displacement volume is set to 10% or less of the maximum displacement volume. is there. According to a fourth aspect of the present invention, the bi-displacement type hydraulic pump 2, the hydraulic pump 2 and the pair of main pipes 3 and 4 are connected in a closed circuit, the output shaft is commonly connected, and the minimum displacement volume is not zero. The first and second variable displacement hydraulic motors 5 and 9 and the valve means 8 for disconnecting the second variable displacement hydraulic motor 9 from the main pipe are provided. The present invention is applied to a method of shifting a hydraulic closed circuit device in which a displacement type hydraulic motor 9 is cut off from the main pipelines 3 and 4 to bring it into a non-operating state. The displacement volume of the second variable displacement hydraulic motor 9 is reduced from the maximum displacement volume of the displacement hydraulic motors 5 and 9;
After the displacement volume of the second variable displacement hydraulic motor 9 reaches the minimum value, the displacement volume of the first variable displacement hydraulic motor 5 is reduced from the maximum value, and the displacement volume of the second variable displacement hydraulic motor 9 is reduced. When the valve displacement is reduced by the minimum displacement volume, the valve means 8 is closed, the displacement volume of the first variable displacement hydraulic motor 5 is set to the maximum value, and then the displacement of the first variable displacement hydraulic motor 5 is set. This is to reduce the shelter volume.

[0007]

When the variable displacement hydraulic motor 9 is connected to the main pipe lines 3 and 4 by the valve means 8, the hydraulic closed circuit device can generate an output torque equivalent to the sum of displacement volumes of the hydraulic motors 9 and 5. When the hydraulic means 9 is shut off from the main pipelines 3, 4 by the valve means 8, the output torque of the hydraulic motor 5 is generated. The output shaft of the variable displacement hydraulic motor in the non-operating state is the clutch shaft 1 from the output shaft of the operating hydraulic motor.
Separated by 5. According to the speed change method of claim 4, even if the second variable displacement hydraulic motor 9 reaches the minimum displacement volume, the valve means 8 is not closed immediately and the first variable displacement hydraulic motor 5 is pushed. After reducing the displacement volume by the minimum displacement volume of the second variable displacement hydraulic motor 9, the valve means 8 is closed and the first variable displacement hydraulic motor 5 is set to the maximum displacement volume. The displacement volume of the first variable displacement hydraulic motor 5 is reduced. As a result, the gear ratio of the hydraulic closed circuit device is changed from the gear ratio corresponding to the minimum displacement volume of the first variable displacement hydraulic motor 5 to the maximum displacement of the first and second variable displacement hydraulic motors 5, 9. It is possible to continuously and smoothly change the gear ratio corresponding to the total of the shelter volume.

Incidentally, in the section of means and action for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. It is not limited to.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the hydraulic closed circuit device according to the present invention will be described with reference to FIG. The tilting amount (pushing volume) of the bi-tilt type hydraulic pump 2 driven by the prime mover 1 is controlled by a tilting amount (pushing volume) controller 11, and a pair of ports of the hydraulic pump 2 has a main pipe line. The variable displacement hydraulic motor 5 is connected in a closed circuit by 3 and 4, and the variable displacement hydraulic motor 9 is connected in a closed circuit via the conduits 6 and 7 branched from the main conduits 3 and 4 and the electromagnetic switching valve 8. Has been done. The output shaft 5a of the hydraulic motor 5 and the output shaft 9a of the hydraulic motor 9 are commonly connected, and torque is transmitted from the output shaft 5a of the hydraulic motor 5 to the outside. The displacement volumes of the variable displacement hydraulic motors 5 and 9 are controlled by displacement volume control devices 11 and 12, respectively.

The electromagnetic switching valve 8 is switch-controlled by opening and closing the selection switch 14, and when the electromagnetic switching valve 8 is switched to the a position, the variable displacement hydraulic motor 9 is connected to the main pipe lines 3 and 4 and the b position. When switched to, the variable displacement hydraulic motor 9 is disconnected from the main pipelines 3, 4. When the gear ratio (output torque) is maximized, the selector switch 14 is opened to switch the electromagnetic switching valve 8 to the a position, and the displacement volumes of the variable displacement hydraulic motors 5 and 9 are set to the maximum. As a result, the output shaft 5a can output an output torque equivalent to that of a hydraulic motor having a total displacement volume of the hydraulic motors 5 and 9.

When the selector switch 14 is closed to switch the electromagnetic switching valve 8 to the b position, the hydraulic motor 9 is separated from the main pipe lines 3 and 4, and the pair of ports of the hydraulic motor 9 are communicated by the electromagnetic switching valve 8. It Therefore, since the hydraulic motor 9 is completely separated from the hydraulic pump 2, the output torque depending on the displacement volume of the hydraulic motor 5 is output from the output shaft 5a.

At this time, the output shaft 9a of the hydraulic motor 9 is rotationally driven by the hydraulic motor 5, but a pair of ports are cut off from the main pipe lines 3 and 4 by the electromagnetic switching valve 8 and communicated through the electromagnetic switching valve 8. Therefore, unlike the conventional example, the pressure oil does not leak from the high-pressure main pipe to the low-pressure main pipe, and the volumetric efficiency of the entire device is prevented from being lowered.

If the displacement volumes of the hydraulic motors 5 and 9 are 25 to 100 cc / rev, respectively, the switching valve 8 is in the a position, and the displacement volumes of the hydraulic motors 5 and 9 are both 100 cc / r.
In the case of ev, the hydraulic closed circuit device functions like a single hydraulic motor of 200cc / rev, and in the case where the switching valve 8 is in the b position and the hydraulic motors 5 and 9 are both 25cc / rev, Functions like a hydraulic motor. As a result, according to such a hydraulic closed circuit device, two hydraulic motors of 25 to 100 cc / rev make it possible to obtain a gear ratio (output) equivalent to that of a single hydraulic motor having a displacement volume range of 25 to 200 cc / rev. Performance)
Can be obtained.

As shown in FIG. 2, the output shaft 9a of the variable displacement hydraulic motor 9 may be commonly connected to the output shaft 5a of the hydraulic motor 5 via the clutch 15. When the hydraulic motor 9 is not separated from the hydraulic motor 5 by the clutch 15, the loss generated by the hydraulic motor 9 is only the torque loss due to the idling of the hydraulic motor, and the loss due to the compressibility of the hydraulic oil does not occur. Therefore, as in the conventional example, the clutch 15
However, if the switching valve 8 is switched to the b position and the hydraulic motor 9 and the hydraulic motor 5 are separated by the clutch 15 at the same time, the torque loss due to the idling of the hydraulic motor 9 can be eliminated. The efficiency of can be further improved.

FIG. 3 shows an embodiment in which various operating information is input to the microcomputer 21 to automatically control the displacement volumes of the hydraulic motors 5 and 9 and the hydraulic pump 2 and the switching operation of the electromagnetic switching valve 8. Show. The displacement volumes of the hydraulic motors 5 and 9 are detected by displacement volume detection devices 22 and 23, and the selection switch 24 is opened / closed by a control signal from the microcomputer 21.

Now, it is assumed that the electromagnetic switching valve 8 is in the a position and the hydraulic motors 5 and 9 are both set to the maximum displacement. From this state, the displacement volume of the variable displacement hydraulic motor 9 decreases, and the minimum value is the displacement volume 23.
Then, the selection switch 24 is closed and the electromagnetic switching valve 8 is switched to the b position according to an instruction from the microcomputer 21. The hydraulic motor 9 is separated from the main pipe lines 3 and 4, and a pair of ports of the hydraulic motor 9 are communicated with each other by an electromagnetic switching valve 8. At this time, the output torque depending on the displacement volume of the hydraulic motor 5 is output to the output shaft.

On the other hand, when it is determined by the signal from the displacement volume detection device 22 that the displacement volume of the hydraulic motor 5 increases and reaches the maximum value when the electromagnetic switching valve 8 is in the b position,
The microcomputer 21 opens the electromagnetic switching valve 8
Switch to position. As a result, the variable displacement hydraulic motor 9
Is again connected to the main conduits 3 and 4, and the output torque from the sum of the displacement volumes of the hydraulic motors 5 and 9 is output from the output shaft 5a.

Microcomputer 2 in response to a shift command
If the switching control is performed in accordance with 1 as follows, the shock due to the switching can be reduced. (1) Set the switching valve 8 to the a position and set the displacement volumes of the hydraulic motors 5 and 9 to 100 cc / rev (200 cc / rev). (2) The displacement capacity of the hydraulic motor 9 is changed from 100cc / rev to 25
Change to cc / rev (200-125cc / rev). (3) The displacement volume of the hydraulic motor 5 should be 75 from 100cc / rev.
Change to cc / rev (125-100cc / rev). (4) At the same time as switching the switching valve 8 to the b position, the displacement volume of the hydraulic motor 5 is changed to 100cc / rev (100cc
/ rev). (5) The displacement volume of the hydraulic motor 5 is changed to 100cc / rev-25 (100cc / rev-25cc / rev).

The present invention particularly relates to a variable displacement hydraulic motor 9,
The following effects can be achieved when configuring the variable displacement hydraulic motor of the oblique shaft type having the sector type valve plate structure. Generally, in an oblique shaft type variable displacement hydraulic motor having a sector type valve plate structure, the displacement volume range is restricted due to its structure. Normally, the minimum displacement volume is said to be ⅓ to ⅕ of the maximum displacement volume. If the minimum value is set to zero, the maximum value will be small, and the displacement volume of the hydraulic motor 5 and the hydraulic motor 9 will be small. In some cases, a desired torque may not be realized because the sum of the displacement and the displacement volume becomes smaller.
Therefore, as in the conventional example shown in FIG. 5, in a configuration in which the minimum displacement volume of the variable displacement hydraulic motor M2 must be set to zero in order to make it inoperative, a desired maximum torque is obtained. In order to set the maximum value and realize the zero tilting as described above, the hydraulic motor 9 becomes larger and the cost increases as compared with the case of adopting the configuration of the present invention. Therefore, the variable displacement hydraulic motor 9 of FIG.
Is a slant shaft type variable displacement hydraulic motor having a sector type valve plate structure, and the minimum displacement volume is 3 times the maximum displacement volume.
If it is set to 0% or less, the hydraulic motor 9 can be made smaller than the conventional device.

Further, an oblique shaft type variable displacement hydraulic motor having a sector type valve plate structure having a zero tilt is very low in marketability and causes a cost increase. However, if the present invention is adopted. Zero tilting is unnecessary, and an oblique shaft type variable displacement hydraulic motor having a sector type valve plate structure with high marketability can be adopted, leading to cost reduction.

In the above embodiment, the electromagnetic switching valve 8 is explained as a spool type switching valve, but if a poppet type switching valve is adopted, the leak is further reduced and the volumetric efficiency of the entire apparatus is further improved. Although the pair of hydraulic motors are each of a variable displacement type, the hydraulic motors other than the hydraulic motor that is cut off and communicated with the main pipeline may be of a fixed displacement type. Further, three or more hydraulic motors may be provided. The output shafts 5a and 9a of the hydraulic motors 5 and 9 may be connected by a gear train as in the conventional example. Furthermore, the variable displacement hydraulic motor 9 may be of a swash plate type, in which case the motor is prevented from increasing in size even if the minimum displacement volume is zero. Further, an oblique shaft type variable displacement hydraulic motor having a so-called ear shaft type cylinder block support structure may be used.

[0022]

As described in detail above, according to the present invention, at least one of the plurality of hydraulic motors connected in a closed circuit to the both tilting hydraulic pumps by the main pipe is a variable displacement hydraulic motor, Since the variable displacement hydraulic motor is cut off and communicated with the main pipeline by the valve means, there is no leakage between the main pipelines when the variable displacement hydraulic motor is deactivated, and the volume of the entire device is reduced. Efficiency is improved. If the output shaft of the hydraulic motor is connected via a clutch, the idling loss of the variable displacement hydraulic motor can be eliminated. By closing the variable displacement hydraulic motor from the hydraulic pump by the valve means, the hydraulic motor is deactivated, so that the minimum displacement volume of the variable displacement hydraulic motor is made zero as in the conventional device. Even if the variable displacement hydraulic motor is an oblique shaft type hydraulic motor having a sector type valve plate structure, it is not necessary to set the minimum displacement volume to 30% or less of the maximum displacement volume. The motor can be made smaller than the conventional device. According to the method of claim 4, the gear ratio of the hydraulic closed circuit device can be continuously and smoothly changed from the minimum value to the maximum value, and a device with less shock can be provided.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a hydraulic closed circuit device according to the present invention.

FIG. 2 is a hydraulic circuit diagram showing another embodiment.

FIG. 3 is a hydraulic and electric circuit diagram showing still another embodiment.

FIG. 4 is a diagram illustrating a conventional device.

[Explanation of Codes] 1 prime mover 2 double tilt type hydraulic pump 3,4 main line 5 variable displacement hydraulic motor 6,7 branch pipeline 8 electromagnetic switching valve 9 variable displacement hydraulic motor 11 pump displacement volume control device 12, 13 motor displacement volume control device 14,24 selection switch 15 clutch 21 microcomputer 22,23 displacement volume detection device

Claims (4)

[Claims] 1. A bi-tilt type hydraulic pump, and a plurality of hydraulic motors which are connected to the hydraulic pump in a closed circuit by a pair of main pipes. At least one hydraulic motor of the plurality of hydraulic motors has a variable capacity. In a hydraulic closed circuit device having a plurality of output shafts of hydraulic motors connected in common, valve means for connecting and disconnecting the input / output port of the variable displacement hydraulic motor to the pair of main pipes is provided. A hydraulic closed circuit device characterized in that 2. The hydraulic closed circuit device according to claim 1, wherein the output shafts of the plurality of hydraulic motors are connected via a clutch. 3. The hydraulic closed circuit device according to claim 1 or 2, wherein the variable displacement hydraulic motor is an oblique shaft hydraulic motor having a sector type valve plate structure, and the minimum displacement volume is 30 times the maximum displacement volume. A hydraulic closed circuit device characterized by being set to be less than or equal to%. 4. A bi-displacement type hydraulic pump, first and second variable capacities in which a closed circuit is connected to the hydraulic pump by a pair of main lines, an output shaft is commonly connected, and a minimum displacement volume is not zero. Type hydraulic motor, and valve means for connecting and disconnecting the second variable displacement hydraulic motor to and from the main conduit, and the valve means disconnects the second variable displacement hydraulic motor from the main conduit. Thus, in the method for shifting the hydraulic closed circuit device in the non-operating state, in the process of changing the gear ratio from the maximum to the minimum, the displacement volumes of the first and second variable displacement hydraulic motors are changed from the maximum displacement state to the first displacement state. The displacement volume of the second variable displacement hydraulic motor is reduced, and the displacement volume of the first variable displacement hydraulic motor is maximized after the displacement volume of the second variable displacement hydraulic motor reaches a minimum value. Reduced from the value, before The valve means is closed and the displacement volume of the first variable displacement hydraulic motor is set to the maximum value when the displacement volume is reduced by the minimum displacement volume of the second variable displacement hydraulic motor, and then the first displacement volume is set to the maximum value. Of the variable displacement hydraulic motor of claim 1, wherein the displacement volume of the hydraulic closed circuit device is reduced.