JP2007170612A - Fluid pressure transmission device and machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide inexpensive hydraulic transmission device and machine capable of stopping rotation of an output shaft securely by stop operation, dispensing with a link mechanism from a driver's seat, and achieving satisfactory operation property. <P>SOLUTION: These fluid pressure transmission device and machine are provided with a fluid pressure pump 33 driven by an engine, discharging oil into an oil passage 21 from either of a pair of first connection ports 23, and sucking oil from an oil passage 22, a fluid pressure motor 34 having a motor shaft 9 taking the oil in the oil passage 21 in from either of a pair of second connection ports 24 and rotating by oil pressure, a bypass passage 25 bypassing the pair of second connection ports 24, and a solenoid valve 12 opening and closing the bypass passage 25. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fluid pressure transmission device and a machine.

  A hydraulic transmission device that forms a closed circuit of oil by combining a hydraulic pump and a hydraulic motor is generally called a hydraulic transmission (Hydro-static Transmission, HST), and one that is put in one housing is called an integrated HST. .

  This type of HST is widely adopted in many construction machines and the like because it can easily move forward, backward and stop by operating the tilt angle of the hydraulic pump.

  Recently, not only construction machines, but also miniaturized HSTs (see, for example, Patent Document 1) have been adopted in combiners and snow removers for rice transplanters and rice harvesters, and are not found in ordinary work machines. It must not be.

  Since the HST originally has a stop function as described above, the operation lever is set to the stop (neutral) position while the engine is running, the work machine is stopped, the driver's seat is left, and the front part is Frequently, a simple inspection of a device or cover is attempted.

  However, even if the operation lever is set to the neutral state, even if a slight amount of oil is discharged from the hydraulic pump and sent to the hydraulic motor, the output shaft of the hydraulic motor rotates and the work machine starts to move. In other words, the movement is contrary to the driver's intention, and in some cases, the machine is caught in the machine during the inspection, which is extremely dangerous.

  To solve this problem, there are two means for preventing the output shaft of the hydraulic motor from rotating. The first is to make oil discharge from the hydraulic pump completely zero. Second, as shown in FIG. 8, a hydraulic motor 104 is connected to the high pressure path 101 and the low pressure path 102 of the hydraulic pump 100, and a bypass path 103 is provided between the high pressure path 101 and the low pressure path 102. Even if a small amount of oil is discharged, the circuit of the high-pressure path 101 and the low-pressure path 102 is bypassed so that the pressure necessary to rotate the hydraulic motor 104 is not generated. A bypass valve 105 is provided in the bypass passage 103 and operated. Reference numeral 100 a denotes a connection port between the high pressure path 101 and the low pressure path 102 of the hydraulic pump 100, and reference numeral 104 a denotes a connection port between the high pressure path 101 and the low pressure path 102 of the hydraulic motor 104.

Thus, a small HST having a manual bypass valve 105 has been commercialized. Some have considered installing a small HST in the machine (see, for example, Patent Document 2).
Japanese Utility Model Publication No. 60-89454 JP-A 61-27366

  However, in an actual machine, it is very difficult to operate such a bypass valve 105 with an operation lever provided in the driver's seat. This is because the HST is often attached to the inside or bottom of the machine, and in order to operate the bypass valve 105 located below the HST, a considerably complicated link structure is required from the operation lever of the driver's seat. This is because these are not easy to install and are expensive and the operability is not improved. For this reason, there was no example used in an actual machine.

  As a result, the first means described above, that is, means for completely eliminating oil discharge from the hydraulic pump is employed.

  That is, in order to realize this, first, the operation lever is moved forward, neutral, backward or backward, neutral, forward several times, and the neutral position of the hydraulic pump where the hydraulic motor does not rotate is searched from the outside. It is necessary to determine the neutral position of the control lever and hydraulic pump. Machines adjusted in this way in the production plant are sold to the general consumer.

  However, since the operating lever provided in the driver's seat and the pump operating part of the hydraulic pump connected to this are connected by several levers and links, wear and looseness occur during use, and the driver's seat A slight error occurs between the operation lever and the pump operation unit. That is, even if the driver intends to be in the neutral state, the hydraulic pump is not in the neutral state, but slightly discharges oil, and as a result, the motor shaft rotates.

  For the driver, if the driver's control lever was set to the neutral position at the beginning of the purchase, the machine was stopped, so a simple inspection and repair work was possible on the front side of the machine with the engine running. Even if the same neutral position is set from a certain point in time, if the machine starts to move, there is a risk of injury or being caught. In addition, the machine may run away without your knowledge.

  For this reason, in a snowplow etc., an electromagnetic clutch is inserted between the engine and the HST. This electromagnetic clutch is electrically operated by a switch provided in the driver's seat. When the engine is on, the engine and the HST are connected to transmit rotation, but when the engine is off, the engine is disconnected and the HST is prevented from rotating. This allows the machine to be checked and repaired safely with the engine running.

  However, the electromagnetic clutch is large in size and placed in the middle of the drive shaft, so that it is difficult to arrange in a small machine and has a complicated configuration. Moreover, it is quite expensive at the moment. However, it is actually used for safety.

  Therefore, the object of the present invention is to stop the rotation of the output shaft reliably without stopping the drive source and using an electromagnetic clutch by the stop operation, and further to a position away from the device such as the driver's seat. It is possible to provide a fluid pressure transmission device and a machine that can be operated in the above-described manner, that a link mechanism can be easily or unnecessary, that an operation unit can be easily installed at low cost, and that has good operability. .

  The fluid pressure transmission device of the present invention includes a fluid pressure pump having a pair of first connection ports that are driven by a drive source to discharge fluid from one side and suck fluid from the other, and the pair of first connection ports. A pair of second connection ports connected to discharge fluid on the discharge side of the first connection port and flowing out fluid on the suction side, and discharged from the discharge side of the first connection port. A fluid pressure motor having an output shaft that rotates by fluid pressure, a bypass path that bypasses between the second connection ports, and an electromagnetic valve that opens and closes the bypass path are provided.

  In the above configuration, the fluid pressure pump is a variable displacement swash plate type axial piston pump, and the fluid pressure motor is a constant displacement type swash plate type axial piston motor.

  The machine according to the present invention includes a fluid pressure transmission device configured as described above, a drive source for driving a fluid pressure pump of the fluid pressure transmission device, an operating unit driven by an output shaft of the fluid pressure transmission device, and the fluid pressure And an operation unit for operating the electromagnetic valve of the transmission.

  According to the fluid pressure transmission device and the machine of the present invention, since the bypass valve is an electromagnetic valve, the bypass path can be reliably opened and closed by an electrical signal from a remote position such as a driver's seat, so the drive source is stopped. In addition, the rotation of the output shaft can be reliably stopped without using an electromagnetic clutch. In addition, since the switch that controls the solenoid valve is operated by the operation unit, the switch can be operated through a simple link mechanism or without using a link mechanism as compared with the case where the bypass valve is directly operated by the link mechanism. Therefore, there are few restrictions on the installation position of the switch, the installation is easy, the operability is good, and the cost can be reduced.

  An integrated hydraulic transmission according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a port block showing a closed circuit of fluid in a hydraulic transmission. FIG. 5 is a hydraulic circuit diagram thereof. The housing 1 integrally holds the hydraulic pump 33 and the hydraulic motor 34, and the internal space thereof communicates with an airtight oil tank (not shown) provided in the housing 1. Oil passages 21 and 22 that form a closed circuit of the oil flow of the hydraulic pump 33 and the hydraulic motor 34 are formed in the port block 2 of the housing 1. Reference numeral 23 denotes a pair of first connection ports for connecting the cylinder block of the hydraulic pump 33 and the oil passages 21 and 22, and reference numeral 24 denotes a communication between the cylinder block of the hydraulic motor 34 and the oil passages 21 and 22. It is a pair of 2nd connection port to connect. Further, in order to bypass the pair of second connection ports 24, a bypass path 25 is connected between the oil paths 21 and 22, and the solenoid valve 12 is provided in the bypass path 25. The illustrated solenoid valve is in an inoperative state in which no current flows through the coil, and the bypass path 25 is opened through the circumferential groove 20a of the spool 20 of the solenoid valve 12. When the solenoid valve 12 is operated, the spool 20 moves, the circumferential groove 20a is separated from the bypass path 25, and the bypass path 25 is closed. Note that 3 is a pump shaft of the hydraulic pump 33, and 9 is a motor shaft of the hydraulic motor 34.

  When the pump shaft 3 is rotated by a drive source such as an engine, the hydraulic pump 34 is operated, and oil is discharged to the oil passage 21 through the connection port 23 and the oil is sucked from the oil passage 22. Therefore, the oil passage 21 becomes a high-pressure passage, the oil passage 22 becomes a low-pressure passage, oil is supplied to the hydraulic motor 34 through the connection port 24, and the hydraulic motor 34 is operated by the oil pressure of the inflowing oil, and becomes a motor shaft serving as an output shaft. 9 rotates. In this case, if the solenoid valve 12 is operated and the bypass path 25 is opened, the pressure difference between the high pressure path and the low pressure path disappears, so that no hydraulic pressure is applied to the hydraulic motor 34, so the hydraulic motor 34 does not operate and the motor shaft 9 rotates. do not do. On the other hand, when the pump shaft 3 rotates in the opposite direction, the oil passage 22 becomes a high pressure passage and the oil passage 21 becomes a low pressure passage. In this case as well, the hydraulic motor 34 is brought into an operating state and a stopped state by opening and closing the electromagnetic valve 12. Can be controlled.

  Reference numeral 5 denotes a swash plate operation shaft that stops the discharge of the hydraulic pump 33 and switches the discharge direction, and is operated by an operation lever on the driver's seat. 27 and 28 are check valves provided between the oil passages 21 and 22 and the space in the housing 1. 29 and 30 are relief valves provided between the oil passages 21 and 22 and the space in the housing 1. Reference numeral 31 denotes a wiring for supplying a current for controlling the electromagnetic valve 12.

  FIG. 2 is a side view of the hydraulic transmission device, and a cross-sectional view taken along line AA ′ in FIG. FIG. 3 is a front view of the hydraulic transmission. 4 is a cross-sectional view taken along the line BB ′ of FIG.

  In FIG. 4, the hydraulic pump 33 is a variable displacement swash plate type axial piston pump. The pump shaft 3 is supported by the housing 1, the pump cylinder block 6 is attached to the pump shaft 3, and rotates together with the pump shaft 3. The pump cylinder block 6 is provided with a plurality of cylinders around the pump shaft 3 in parallel with the pump shaft 3, each provided with a piston 8, and urged so that the piston 8 protrudes from the pump cylinder block 6. Has been. A swash plate 4, which is a swash plate, is disposed so as to intersect the shaft 3, and is supported by the housing 1 so as to be rotatable about an axis intersecting the shaft 3, and the shaft also serves as the swash plate operating shaft 5. The tip of the piston 8 is in sliding contact with the surface of the swash plate 4. The side of the pump cylinder block 6 opposite to the swash plate 4 is in sliding contact with a valve plate 7 that forms a connection port 23 that connects the rear end of each cylinder and the oil passages 21 and 22. The valve plate 7 is fixed to the housing 1.

  When the pump shaft 3 is rotated by an engine or the like, the cylinder block rotates simultaneously, and the piston 8 reciprocates by slidingly contacting the swash plate 4. For example, when the pump shaft 3 rotates in one direction, the piston 8 climbing the inclined surface of the swash plate 4 compresses the inside of the cylinder, discharges oil to the oil passage 21, and conversely, the piston 8 descending the inclined surface is the oil passage 22. Oil is sucked into the cylinder. When the swash plate operating shaft 5 is operated to rotate the swash plate 4 and the tilt angle with respect to the pump shaft 3 is set to 90 degrees from the state shown in the figure, the piston 8 does not reciprocate even if the pump shaft 3 rotates. Oil discharge is lost. If the swash plate 4 is slightly deviated from 90 degrees, the piston 8 reciprocates, so there is a slight discharge. When the swash plate 4 is further tilted in the opposite direction, the piston 8 reciprocates, but the oil passage 22 is discharged and the oil passage 21 is sucked.

  The hydraulic motor 34 has substantially the same configuration as the hydraulic pump 33, but is a constant capacity type swash plate type axial piston motor, 9 is a motor shaft serving as an output shaft, 10 is a motor cylinder block, 11 is a motor valve plate, and 8a is a piston. Reference numeral 4a denotes a swash plate. Here, the swash plate 4 a is fixed to the housing 1. When the oil passage 21 is a high-pressure passage, the oil pressure flowing from the oil passage 21 through the connection port 24 pushes the swash plate 4a with the force by which the piston 8a in the cylinder is pushed out, and the piston 8 moves down the slope of the swash plate 4a. By sliding in this way, the motor cylinder block 10 rotates in one direction, and the motor shaft 9 rotates. In addition, oil flows out to the oil passage 22 through the connection port 24 by the piston 8a climbing the slope of the swash plate 4a. When the oil passage 22 is on the high pressure passage side, the motor cylinder block 10 rotates in the reverse direction.

  In the solenoid valve 12, 13 is a coil, 14 is an iron core, 15 is a solenoid body, 16 is a coil case, 17 is a shaft, 19 is a bush, and 20 is a spool that intersects a bypass 25 connected to the shaft 17. 20 protrudes from the electromagnetic valve 12 into a recess in the housing 1 by a spring. 1 and 4 is a state in which no current is supplied to the coil 13 and the coil 13 is not energized, and the spool 20 protrudes from the solenoid valve 12 by a spring (not shown) to the surface of the spool 20. Since the formed circumferential groove 20 a is located in the bypass path 25, the bypass path 25 is opened. When power is supplied to the coil 13, the shaft 17 is attracted to the iron core 14 against the spring, and the circumferential groove 20 a is separated from the bypass path 25, so that the bypass path 25 is closed. Control of power feeding to the coil 13 is performed by a switch (not shown), and the switch and the coil 13 are connected by a wiring 31. The operation unit for operating the switch is provided so as to be linked to the operation lever for operating the swash plate operation shaft 5 of the driver's seat, or is installed separately from the operation lever.

  FIG. 6 shows a drive mechanism of a machine such as a vehicle using the hydraulic power transmission device of the above embodiment. Reference numeral 40 denotes an engine serving as a drive source, 41 a belt, 42 an electromagnetic clutch, 43 a joint, 44 a hydraulic transmission device according to the above embodiment, 45 a gear reducer, 46 an axle, and 47 a wheel serving as an operating unit. is there. The electromagnetic clutch 42 may not be provided.

  FIG. 7 shows a case where the hydraulic power transmission device of the above embodiment is applied to, for example, a snowplow. For example, a diesel engine is used as the engine 40. Wheels 47 connected to the axle 46 drive the crawler 51. The driver seat 52 has a switch as an operation unit for operating the electromagnetic valve.

  In the driver's seat 52, the operation lever for operating the swash plate operation shaft 5 and the switch of the solenoid valve 12 are combined so that the switch of the solenoid valve 12 is turned on when the operation lever is in the forward or reverse position. Thus, the high pressure path and the low pressure path are interrupted, so that the hydraulic motor 34 rotates and the snowplow is in an operating state. When the operation lever is in the neutral position, the solenoid valve 12 is turned off, and the high pressure path and the low pressure path are bypassed. Even if the swash plate operating shaft 5 of the hydraulic pump 33 and the operating lever are displaced and the operating lever is in the neutral position, even if the oil is discharged from the hydraulic pump 33, Since it bypasses, the hydraulic motor 34 is not rotated. As a result, oil discharge from the hydraulic pump 33 can be reduced to zero, and the high pressure passage and the low pressure passage can be bypassed and the pressure required to rotate the hydraulic motor 34 can be prevented, thereby providing double safety. Can be easily realized.

  In addition, 48 is an auger which scrapes snow, 49 is a blower which discharges snow, 50 is a shooter which determines the discharge direction of snow.

  According to this embodiment, the solenoid valve 12 and the driver's seat switch are connected only by wiring, and the operation unit that operates the solenoid valve via the switch operates the switch directly or via a simple link mechanism. Compared to a link mechanism using a manual bypass valve, it is much easier, has a higher degree of freedom in switch arrangement, is cheaper, and is more reliable. Further, if such a small HST is used, the electromagnetic clutch is not required, and the configuration of the snowplow and other machines becomes easy and the size and weight are reduced. That is, a machine that is reduced in size and weight, low in price, and excellent in safety is realized.

  In the above description, the case where the operation lever and the solenoid valve switch are linked is described, but these may be operated individually. Further, the switch is not limited to the driver's seat, and the switch may be directly operated by being arranged at a position where it can be easily operated by the hydraulic power transmission device.

  The machine of the present invention is a vehicle or the like that moves an object with a rotating shaft. However, as a relatively low speed machine, for example, a construction machine or a snowplow, a mower, a lawn mower, a harvester, a transporter, a speller, etc. There is.

  In the present invention, since the bypass path is opened and closed by a solenoid valve for stopping the output shaft, it is possible to use a fluid pressure pump other than the swash plate type axial piston pump. The fluid pressure pump preferably has a means for stopping the discharge of the fluid pressure while being driven by a drive source, but since the output shaft can be stopped by an electromagnetic valve, it does not have the above means. May be.

FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG. 2 showing a closed circuit of the integrated hydraulic transmission according to the embodiment of the present invention. It is a side view of a hydraulic power transmission. It is a rear view. FIG. 4 is a sectional view taken along line BB ′ in FIG. 3. It is a hydraulic circuit diagram. It is a block diagram of a drive mechanism. It is a side view of the use condition of a snowplow. It is sectional drawing which shows the closed circuit of the integrated hydraulic transmission of a prior art example.

Explanation of symbols

1 Housing 3 Pump shaft 4 Swash plate 6 Pump cylinder block 8 Piston
9 Motor shaft 10 Motor cylinder block 12 Solenoid valve 21 Oil passage 22 Oil passage 23 First connection port 24 Second connection port 25 Bypass passage 33 Hydraulic pump 34 Hydraulic motor 40 Engine 44 Hydraulic transmission device 46 Axle

Claims (3)

  A fluid pressure pump having a pair of first connection ports driven by a driving source to discharge fluid from one side and suck fluid from the other, and the first connection port connected to the pair of first connection ports And a pair of second connection ports through which fluid on the discharge side flows in and flows out on the suction side, and has an output shaft that is rotated by the fluid pressure of the fluid discharged from the discharge side of the first connection port A fluid pressure transmission device comprising: a fluid pressure motor; a bypass path that bypasses between the second connection ports; and an electromagnetic valve that opens and closes the bypass path.   2. The fluid pressure transmission device according to claim 1, wherein the fluid pressure pump is a variable displacement swash plate type axial piston pump, and the fluid pressure motor is a constant displacement type swash plate type axial piston motor. The fluid pressure transmission device according to claim 1, a drive source for driving a fluid pressure pump of the fluid pressure transmission device, an operating unit driven by an output shaft of the fluid pressure transmission device, and the fluid pressure A machine including an operation unit for operating a solenoid valve of a transmission device.

Images