JP3607814B2 - Device for increasing torque at startup of fluid pressure motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluid pressure motor, and more particularly to a device that compensates for torque shortage at the time of starting a hydraulic motor.
[0002]
[Prior art and problems to be solved by the invention]
For example, in a construction civil machine such as a hydraulic excavator that requires a large torque, a rotary or reciprocating hydraulic motor is used for turning or traveling. As an example of such a hydraulic motor, an inscribed gear motor unit ("" revolving motion) in which a star (star) -shaped outer tooth member performs a planetary motion (spinning and revolving motion) in a ring-shaped inner tooth member by the action of hydraulic pressure. Some may also be referred to as a “gerotor mechanism”.
Generally, the torque efficiency at the start of the fluid pressure motor is about 10 to 10 times higher than the torque efficiency at the time of operation due to various factors at the start, for example, energy loss due to friction between components, leakage of pressure oil, etc. 25% lower. A hydraulic excavator equipped with such a hydraulic motor requires a large torque when starting to run on an uphill or a rough road, such as a mud road, but it is commensurate with the load due to low torque efficiency at start-up. Output torque may not be obtained and the hydraulic motor may not start. Further, for example, even if an attempt is made to turn the turning body while the hydraulic excavator is traveling on a hill, there may be a case where a torque sufficient to start the hydraulic motor may not be obtained for the same reason as described above.
[0003]
Conventionally, attempts have been made to improve the machining accuracy of components in order to improve the torque efficiency at the start of the hydraulic motor. In particular, in the gerotor type hydraulic motor, the shape of the ring and star was optimized, and the processing accuracy was improved to achieve smooth rotation of the star in the ring.
[0004]
The present invention relates to compensating for the difference between the operating torque efficiency and the starting torque efficiency of the hydraulic motor in a manner different from such conventional approaches.
[0005]
Thus, an object of the present invention is to provide a device capable of reliably starting a fluid pressure motor by increasing the starting torque of the fluid pressure motor to compensate for the difference between the operating torque efficiency and the starting torque efficiency. .
[0006]
[Means for Solving the Problems]
The present invention relates to a fluid pressure used in combination with a fluid pressure motor operatively connected to a load via a rotatable transmission shaft and adapted to operate in an operating torque mode and a starting torque mode. Provided is a motor starting torque increasing device. The start-up torque increasing device according to the present invention includes a fluid pressure cylinder unit including a drive piston rod member that is disposed laterally as a whole with respect to the transmission shaft and can reciprocate by the action of fluid pressure, and the transmission shaft and the drive piston rod. If the start-up torque is not sufficient to operate the hydraulic motor during start-up, the drive force of the drive piston rod member is transmitted to the transmission shaft to provide additional start-up torque. Driving force transmitting means for enabling the fluid pressure motor to operate, and after the fluid pressure motor is started, the fluid pressure motor operates in a torque mode during operation and between the piston rod member and the transmission shaft. The power transmission relationship is released.
[0007]
Preferably, the driving force transmitting means of the starting torque increasing device includes a plurality of parallel longitudinal pinion teeth provided around the outer periphery of at least a part of the length of the transmission shaft, and a driving piston rod member. A plurality of rack teeth meshing with the pinion teeth, and when the fluid pressure motor operates in the torque mode during operation, the drive piston rod member is moved a predetermined distance by the transmission shaft, The rack teeth of the drive piston rod member and the pinion teeth of the transmission shaft are disengaged by movement.
[0008]
The drive piston rod member of the start-up torque increasing device of the present invention can be linked with a load, for example, an appropriate torque transmission shaft located between a crawler of a mini excavator and a traveling hydraulic motor, and the transmission shaft is connected to the hydraulic motor. The output shaft may be an output shaft. However, when the speed reducer is interposed between the load and the fluid pressure motor, it may be the output shaft of the speed reducer. Further, the drive piston rod member of the start-up torque increasing device of the present invention can increase the start-up torque of the hydraulic motor in cooperation with the revolution output portion of the gerotor hydraulic motor.
[0009]
The start-up torque increasing device of the present invention is preferably associated with its output shaft in a state of being incorporated in the housing of the hydraulic motor.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram for explaining the basic configuration and the operating principle of the present invention. A fluid pressure motor 10 is operatively connected to a load (not shown in FIG. 1) via a transmission shaft 14 rotatably supported by bearings 12a and 12b. The illustrated motor is any type of fluid pressure motor, for example a rotary hydraulic motor such as a gerotor hydraulic motor, a reciprocating hydraulic motor such as an axial piston motor, and may also be considered as a hydraulic or pneumatic motor.
[0011]
The motor 10 typically has at least two hydraulic oil outlets. As will be appreciated by those skilled in the art, the rotational direction of the motor can be reversed by switching the introduction of pressure oil between the two hydraulic oil inlets and outlets. Now, one hydraulic oil inlet / outlet (for example, 16) of the motor is connected to the high pressure hydraulic oil source 18 via the line 24, and the other inlet / outlet 20 is connected to the low pressure hydraulic oil source 22 such as the return oil reservoir via the line 26. It shall be.
[0012]
In general, a motor operates in a torque mode during start-up and a torque mode during operation, and the torque efficiency during start-up is lower than the torque efficiency during operation. This is because friction between motor parts at the time of start-up, energy loss in the power transmission system, oil leakage inside the motor due to manufacturing tolerances of the motor parts, etc. inevitably occur. As an example, in a hydraulic motor of the type having an inscribed gear motor part or a gerotor mechanism part, the torque efficiency during operation is about 85%, whereas the torque efficiency during start-up is about 70%.
[0013]
The present invention relates to a start-up torque increasing device configured to generate an additional output torque only at start-up and compensate for a difference between the start-up torque and the start-up torque. Reference numeral 30 indicates. The start-up torque increasing device 30 for a hydraulic motor according to the present invention includes a hydraulic cylinder unit 32, and a drive piston rod member 34 is disposed laterally with respect to the transmission shaft 14 as a whole. The pistons 36a and 36b on the opposite sides of the piston rod 34 are respectively linked to the fixed cylinder blocks 38a and 38b to form hydraulic chambers 40a and 40b. In the illustrated preferred example, these are the holes 42a and 42b, respectively. Via lines 24 and 26, fluid communication with the sources 16 and 22 is provided in parallel with the hydraulic system and return oil system of the hydraulic motor. Thus, when high-pressure hydraulic oil from the pressure oil source 16 is introduced into the chamber 40a via the line 24, the piston rod 34 moves to the left as viewed in FIG. 1, and the hydraulic oil in the chamber 40b enters the reservoir 22 via the line 26. It will be understood that returning and introducing pressure oil into the chamber 40b provides the reverse operation.
[0014]
As well as FIG. 1, it will be better understood with reference to FIG. 2 showing a main part of the cross section taken along line 3-3 of FIG. 2 and FIG. In addition, the starting torque increasing device 30 further includes driving force transmitting means 44 provided between the piston rod member 34 of the hydraulic cylinder unit and the transmission shaft 14 associated with the hydraulic motor. In the illustrated embodiment, the driving force transmitting means 44 includes a plurality of parallel longitudinal pinion teeth 46 provided around the outer peripheral portion of at least a part of the length of the transmission shaft 14, and a driving piston rod member. A plurality of rack teeth 48 are provided at 34 selected length portions and mesh with the pinion teeth. More particularly, as best seen in FIG. 3, a longitudinally toothed rack-like member 50 meshes with the pinion teeth 46 of the transmission shaft, preferably at its side approximately at the center of the length of the piston rod 34. It is attached. As can be seen in FIGS. 1 and 3, when the piston rod 34 of the hydraulic cylinder unit 32 moves a predetermined distance in either the left or right direction, in other words, when the piston 36a or 36b reaches its stroke end, the rack teeth 48 are It should be noted that the power transmission relationship between the piston rod of the hydraulic cylinder unit and the transmission shaft is released from the pinion teeth 46 of the transmission shaft 14.
[0015]
The transmission shaft 14 may be an output shaft of the hydraulic motor 10 or an extension thereof. As a modification, the transmission shaft 14 is an output shaft of a speed reducer (not shown) provided between the load and the hydraulic motor 10. Alternatively, it may be a revolution output shaft portion of a star-shaped external gear member of a gerotor hydraulic motor as will be described later.
[0016]
The operation principle of the present invention shown in FIG. 1 will be described. Even when the start-up torque is not sufficient for operating the hydraulic motor at the time of start-up, the pressure oil from the source 16 passes through the line 24 to the hydraulic cylinder chamber 40a. The piston rod 34 is driven and driven linearly to the left side. Then, the driving force is transmitted to the transmission shaft due to the meshing of the rack teeth 48 of the piston rod and the pinion teeth 46 of the transmission shaft, and additional starting torque is generated in the transmission shaft. This additional start-up torque is added to the start-up output torque of the hydraulic motor 10 itself, thus starting the hydraulic motor and operating the load. Once the hydraulic motor is started and switched to the operating torque mode, the transmission shaft is driven to rotate with the operating torque, and at the same time, the piston rod continues to move linearly. Finally, the pinion teeth of the transmission shaft and the rack teeth of the piston rod Will come off.
[0017]
It will be understood that when the hydraulic motor is to be rotated in the direction opposite to that described above, the pressure oil may be introduced into the right hydraulic cylinder chamber 40b. In the above configuration, if the hydraulic motor is once started and then stopped, and if it is desired to start the hydraulic motor in the same rotational direction, the hydraulic motor is first started in the reverse direction and then the hydraulic motor is rotated. One skilled in the art will recognize that the direction needs to be reversed by lever operation.
[0018]
FIG. 2 shows a configuration example in which the startup torque increasing device of the present invention is incorporated into a mini-excavator hydraulic motor having a gerotor mechanism. The structure and operating principle of this type of hydraulic motor are well known and will be described only briefly. If necessary, please refer to JP-A-6-294373 and JP-A-9-177656 of the present applicant.
[0019]
The hydraulic motor 100 is shown in a state where a fixed housing portion 52 is attached to an excavator frame 54 and a rotary housing portion 56 is attached to a crawler 60 via a sprocket 58 as a traveling motor for a mini excavator. The hydraulic motor has an oil inlet and an oil outlet that can be selectively connected to a high pressure hydraulic oil and a low pressure hydraulic oil source. The hydraulic motor also has a gerotor mechanism portion 62 housed in a fixed housing. The gerotor mechanism portion includes a plurality of ring-shaped members 64 with internal teeth, and a ring-shaped member that can rotate and revolve with respect to the ring-shaped member. The star-shaped member 66 provided in the inside and having one external tooth smaller than the internal tooth and a plurality of volume chambers formed between the internal tooth and the external tooth are provided. Further, a valve that is arranged between the oil inlet and the oil outlet and sequentially passes the high pressure hydraulic oil source and the low pressure hydraulic oil source through the volume chamber so that the star-like member can revolve with respect to the ring-like member. A device 68 is provided. As illustrated, one end of the main drive 70 is splined to the star-like member 66. At the other end of the main drive, an output shaft 74 connected to the rotary housing via a gear mechanism 72 is disposed in a power transmission relationship. The start-up torque increasing device 30 of the present invention is preferably arranged in relation to the output shaft 74 as shown. In addition, you may arrange | position the starting torque increase apparatus of this invention so that an additional starting torque may be given with respect to the revolution output extension part 76 of the star-shaped member 66. FIG. However, in this case, the size of the entire hydraulic motor may increase due to a structural design change for arranging the startup torque increasing device.
[0020]
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating the principle of a startup torque increasing device according to the present invention.
FIG. 2 is a side view showing a state where the starting torque increasing device of the present invention is incorporated in a gerotor-type hydraulic motor, and the hydraulic motor is shown attached to a mini excavator.
3 is a schematic diagram of a main part in a cross section taken along line 3-3 in FIG. 2, and is a diagram showing a configuration of a driving force transmitting means of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Hydraulic motor 14 Transmission shaft 30 Torque increase device 32 at start-up Hydraulic cylinder unit 34 Drive piston rod member 44 Drive force transmission means 46 Pinion tooth 48 Rack tooth

Claims (7)

Fluid pressure motor starting torque used in combination with a fluid pressure motor operatively connected to the load via a rotatable transmission shaft and adapted to operate in the operating torque mode and the starting torque mode A fluid pressure cylinder unit including a drive piston rod member which is disposed in a transverse direction as a whole with respect to the transmission shaft and can reciprocate by the action of fluid pressure; and between the transmission shaft and the drive piston rod member. If the starting torque is not sufficient to operate the hydraulic motor at startup, the driving force of the drive piston rod member is transmitted to the transmission shaft to provide additional starting torque, thereby Driving force transmitting means for operating the pressure motor, and after the fluid pressure motor is started, the fluid pressure motor is Startup torque increase and wherein the power transmission relationship is to be released between the piston rod member to the transmission shaft as well as operate in the mode. The drive force transmission means includes a plurality of parallel longitudinal pinion teeth provided around the outer periphery of at least a part of the length of the transmission shaft, and a selected length portion of the drive piston rod member. A plurality of rack teeth meshing with the pinion teeth. 2. The starting torque increasing device according to claim 1, wherein the rack teeth and the pinion teeth of the transmission shaft are disengaged. 2. The start-up according to claim 1, wherein the fluid pressure chambers at the ends of the drive piston rod members opposite to each other are selectively communicated with a high-pressure working fluid system and a return working fluid system of the fluid-pressure motor, respectively. Torque increase device. 2. The start-up torque increasing device according to claim 1, wherein the transmission shaft is an output shaft of a fluid pressure motor. 2. The start-up according to claim 1, wherein the speed reducer is interposed between the load and the fluid pressure motor, and the transmission shaft is an output shaft of the speed reducer operatively connected to the load. Torque increasing device. 5. The starting torque increasing device according to claim 4, wherein the fluid pressure cylinder unit is disposed in a housing of the fluid pressure motor. The fluid pressure motor includes an oil inlet and an oil outlet that can be selectively connected to a high-pressure hydraulic oil and a low-pressure hydraulic oil source, a ring-shaped member with a plurality of internal teeth, and a ring-shaped member that can rotate and revolve with respect to the ring-shaped member. A star-shaped member having one external tooth smaller than the internal teeth, a gerotor mechanism having a plurality of volume chambers formed between the internal teeth and the external teeth, and a splined connection to the star-shaped member. The high pressure hydraulic oil source and the low pressure hydraulic oil source are sequentially disposed in the volume chamber so that the star-shaped member can rotate and revolve with respect to the ring-shaped member. The start-up torque increasing device according to claim 1, wherein the starting torque increasing device is an internal gear hydraulic motor including a valve mechanism to be passed through.

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