JP4319397B2 - 2-speed radial piston motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a switching valve device for a two-speed radial piston motor, particularly a two-speed multi-stroke (multi-stroke) radial piston motor.
[0002]
[Prior art and problems to be solved by the invention]
The radial piston motor is typically widely used as a constant-capacity low-speed high-torque motor for turning or running various civil engineering machines such as mobile cranes and truck cranes. As is well known, this type of radial piston motor includes a mono-stroke (eccentric) type and a multi-stroke (multi-stroke) type. As is well known to those skilled in the art, the radial piston motor can operate as a high-speed low-torque motor by changing the number of pressure oil supply ports by adopting a 2-speed switching valve. In other words, the radial piston motor can be switched between a low speed high torque (large capacity) mode and a high speed low torque (small capacity) mode by a two-speed switching valve. As an example, the structure and operating principle of a conventional two-speed multi-stroke (multi-stroke) radial piston motor are shown in FIGS.
[0003]
The radial piston motor 10 includes a plurality of radial directions including a ring-shaped cam 14 having an inner cam surface 12, and a roller 16 that is configured to roll relative to the cam 14, each engaged with the cam surface. A displacement mechanism portion 24 including a piston block 18 and a cylinder block 22 provided with a plurality of bores 20 for housing these pistons, and a housing 26 adjacent to the displacement mechanism portion 24 to push hydraulic oil. Timing provided with a plurality of through holes 30 provided at equiangular intervals in the circumferential direction for sequentially supplying and discharging pressure oil through the oil holes 28 provided in the cylinder block correspondingly to the piston of the retraction mechanism portion A plate or valve plate 32; An output shaft 34 for extracting the reciprocating motion of the piston as a rotational motion of the shaft is splined to the cylinder block 22 at 36 and supported by a tapered roller bearing 40 in a casing 38 fixed to the cam 14 and the housing 26. Has been. Two hydraulic oil ports A and B that can be selectively switched between a high pressure state and a low pressure state communicate with a selected number of through holes 30 in the valve plate to operate between the large capacity mode and the small capacity mode. A two-speed switching valve 42 for switching is incorporated.
[0004]
The operation principle of the radial piston motor (which is also generally referred to as “cam motor” in the following description is sometimes referred to as a cam motor) 10 is well known to those skilled in the art. As described above, the plurality of pistons 18 are reciprocated in the bore under the action of the hydraulic pressure from the valve plate through the oil holes 28, and the roller 16 attached to the piston tip rolls on the cam surface 12. By moving, a rotational motion is generated in the cylinder block, and this rotational motion is extracted as a rotational motion of the output shaft.
[0005]
In the illustrated example, the valve plate includes twelve through holes 30 corresponding to the six cam peaks of the ring cam. Also, the illustrated switching valve is a two-position switching valve that is normally in the left position as shown in FIGS. 6 and 7A by a spring 44 (this corresponds to the large capacity mode of the cam motor). In the large capacity mode, the tank pressure acts at the reference numeral 46. Thus, in the illustrated two-speed cam motor 10, when the two-position switching valve 42 is in the normal left position, for example, the port A is connected to every other through hole 30 of the valve plate 32 via one supply / discharge line 48. The port B communicates with every other through hole 30 of the valve plate through the two supply / discharge lines 50 and 52 through the diversion flow path in the switching valve.
[0006]
To switch the cam motor from the large capacity mode (shown in FIG. 7A) to the small capacity mode (correspondingly, the state of the switching valve is shown in FIG. 7B), a high pressure from a hydraulic pilot source (not shown) is used. A pilot signal is applied to the switching valve 42 at reference numeral 46. Then, the switching valve takes the right position in FIG. 6, and thus, as can be seen in FIG. 7B, the port A leads to every other through hole 30 of the valve plate via the supply / discharge line 48 and via the supply / discharge line 50. The port B communicates with every other through hole 30 of the valve plate via one supply / discharge line 52. Now, assuming that port A is in a high pressure state, a total of six pistons out of eight communicate with port A through valve plate through holes 30 and corresponding oil holes 28. As can be understood by those skilled in the art from FIG. 6, four of the six pistons are in the expansion stroke and the other two are in the compression stroke, so the former exerts motor action and the latter does not. The reverse pumping action will be exhibited. Thus, the motor action exerted by the cam motor as a whole exhibits a torque that is ½ of the torque in the normal large capacity mode, and thus the cam motor operates in the small capacity mode. Conversely, when high pressure hydraulic oil acts on port B, two of the eight pistons receive the action of the pressure oil to exert a motor action, and this is also 1 / of the torque generated in the normal large capacity mode. A torque of 2 is exerted, and the cam motor operates in a small capacity mode and operates at a high speed.
[0007]
The conventional two-speed cam motor of the three-passage (supply / discharge line) system as described above causes a difference in operation efficiency due to the difference in the number of pistons that are in a high pressure state in the left rotation and the right rotation in the small capacity mode. It may happen. More specifically, the more the number of pistons in the high pressure state, the more the total frictional force with respect to the movement of the pistons. In addition, some pistons exhibit a pumping action, so the cam motor As a whole, the torque efficiency obtained by this is greatly reduced. It is clear that the volume efficiency decreases as the number of high-pressure pistons increases. Experiments show that in the small capacity mode of the cam motor, when the supply pressure is 28 MPa, the difference in torque efficiency is 15% to 20% when the cam motor rotates left and right. In this case, the difference in volumetric efficiency is about 5%.
[0008]
Thus, if there is a difference in torque efficiency between the left and right rotations of the cam motor in the small capacity mode, there may be a disadvantage that the forward and reverse speeds are different when the cam motor is used for traveling. In addition, when independent traveling cam motor circuits are provided on the left and right sides of the vehicle, if the piping configuration is bilaterally symmetrical, the high and low pressure ports are reversed on the left and right, so that the vehicle does not travel straight in the small capacity mode, which is dangerous. Therefore, in general, such a drawback is overcome by reversing the motor in the left and right direction by reversing the timing of the left and right valve plates with respect to the displacement mechanism. However, such countermeasures require the use of cam motors with different configurations on the left and right sides of the vehicle, which is troublesome for inspection and maintenance and requires stocking of cam motors with different configurations, resulting in high costs.
[0009]
In view of such drawbacks, the present invention is to provide a two-speed radial piston motor configured to eliminate the difference in torque efficiency due to the difference in the rotation direction of the motor in the small capacity mode.
[0010]
Another object of the present invention is to provide a two-speed multi-stroke radial piston motor configured to eliminate the difference in torque efficiency due to the difference in the rotation direction of the motor in the small capacity mode.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a plurality of radial pistons including a cam having a cam surface and a roller adapted to roll relative to the cam with each cam engaged with the cam surface. And a displacement mechanism portion including a cylinder block provided with a plurality of bores for storing these pistons, and a plurality of displacement mechanisms provided at equal angular intervals in the circumferential direction for sequentially supplying and discharging hydraulic oil to and from the pistons of the displacement mechanism portion. A valve plate having a through hole, means for extracting the reciprocating motion of the piston as a rotational motion of the shaft, and two hydraulic oil ports that can be selectively switched between a high pressure state and a low pressure state. A two-speed radial piston module having a switching valve device for switching the operation between a low-speed high-torque (large capacity) mode and a high-speed low-torque (small capacity) mode. For the other. According to a feature of the present invention, the switching valve device can communicate with two hydraulic fluid ports and has at least four separate supply / discharge lines leading to a selected number of through holes in the valve plate. When one of the two hydraulic oil ports is set to a high pressure, a hydraulic pilot source is applied to the main selector valve to switch the high pressure hydraulic oil port accordingly. And an auxiliary switching valve operable to communicate with only one of the valve supply and discharge lines.
[0012]
The present invention also includes a plurality of rollers provided radially within a cam ring having an inner cam surface, each of which is adapted to roll relative to the inner cam surface in a engaged state. And a displacement mechanism part including a single cylinder block provided with a plurality of bores for housing these pistons, and hydraulic oil are sequentially supplied to and discharged from the piston of the displacement mechanism part at equal angular intervals in the circumferential direction. Selection of valve plate with valve plate provided with a plurality of through holes provided, means for taking out the reciprocating motion of the piston as rotational motion of the shaft, and two hydraulic oil ports that can be selectively switched between a high pressure state and a low pressure state A two-speed motor having a switching valve device for switching the operation between the low speed high torque (large capacity) mode and the high speed low torque (small capacity) mode by communicating with the number of through holes. In the multi-stroke radial piston motor, the switching valve device has at least four separate supply / discharge lines that can communicate with the two hydraulic oil ports and communicate with a selected number of through holes in the valve plate. A switching valve and a main switching valve are provided in cooperation with each other. When one of the two hydraulic oil ports is set to a high pressure, a pilot pressure from a hydraulic pilot source is applied to the main switching valve accordingly. A two-speed multi-stroke radial piston motor is provided that has an auxiliary switching valve operable to communicate only one of the hydraulic oil ports with only one of the supply / discharge lines of the main switching valve.
[0013]
According to the configuration of the present invention, regardless of which of the two hydraulic oil ports has a high pressure, the hydraulic oil port communicates with any one of the four supply / exhaust lines in the motor. Any three of the through holes in the valve plate are always in communication with the high pressure port, thus substantially eliminating the difference in efficiency when the motor rotates left and right.
[0014]
In a preferred embodiment, when one of the two hydraulic oil ports is at a high pressure, the main switching valve causes one of the hydraulic oil ports to communicate with one of the four supply / discharge lines by the pilot pressure and the remaining one. A first position where the three supply / discharge lines communicate with the other low-pressure hydraulic oil port, a neutral position taken when no pilot pressure is generated, and a pilot pressure when the other hydraulic oil port is high The second hydraulic fluid port moves between a second position where the other hydraulic fluid port is connected to one supply / discharge line other than one supply / discharge line and the remaining three supply / exhaust lines are communicated to one of the low-pressure hydraulic fluid ports. Has a spool that can.
[0015]
In a preferred form, the main switching valve has pilot chambers on opposite sides of the spool, each of which is connected to a hydraulic pilot source via an auxiliary switching valve. It is desirable that the four supply / discharge lines communicate with through holes located at predetermined angular intervals of the valve plate.
[0016]
In one embodiment, the valve plate is provided with 12 through holes, in which case the angle is 120 °.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a two-speed multi-stroke radial piston motor 110 of the present invention. The cam motor 110 of the present invention is substantially the same as the conventional cam motor of FIG. 4 except for the valve plate 132 and the switching valve device 142 provided in cooperation therewith. This will be described with reference to FIG.
[0018]
The difference in configuration between the cam motor shown in FIG. 1 and the conventional cam motor shown in FIG. 4 is that there are four hydraulic oil supply / discharge lines (54 to 60) selectively connected to port A and port B. is there. That is, as best understood in FIGS. 1 and 2, the switching valve device 142 has an internal structure that divides the hydraulic lines of ports A and B into two hydraulic oil supply / discharge lines 54, 56 and 58, 60, respectively. A three-position main switching valve 62 having a configuration is provided. In the preferred embodiment, the main switching valve 62 is connected to the port A according to the pilot pressure from one of the two hydraulic oil ports, for example, when the port A is at a high pressure. A first position (see FIGS. 2 and 3A) where the exhaust line 54 is communicated and the remaining three supply / exhaust lines 56, 58, 60 and the other hydraulic oil port B are communicated, and when no pilot pressure is generated When the port B is at a high pressure and the neutral position (state shown in FIG. 2), the port B communicates with the supply / discharge line 60 according to the pilot pressure from the high-pressure hydraulic oil port and the remaining three It has a spool 64 that can move between the supply / discharge lines 54, 56, and 58 and a second position (see FIGS. 2 and 3B) that allows the port B to communicate. In the illustrated embodiment, each of the four supply / discharge lines 54, 56, 58, 60 communicates with three through holes 130 that are located at intervals of 120 ° of the valve plate 132.
[0019]
As another important feature of the present invention, the switching valve device 142 of the present invention has a high-pressure signal (high-pressure operation) of either port A or port B as means for enabling the operation of the main switching valve. A three-position auxiliary switching valve 68 is provided, which is operated by oil) and allows the above-described pilot pressure passing through the hydraulic pilot line 66 to pass to the main switching valve. Thus, if the cam motor 110 is to be operated with the port A at a high pressure (for example, if the cam motor is rotated in one direction to advance the vehicle), the port B is in a low pressure or tank pressure state. Due to the high pressure of A, the auxiliary switching valve 68 takes the left position as seen in FIG. Then, the hydraulic line 66 is connected to the passage 70 via the auxiliary switching valve 68. Then, the pilot pressure in the hydraulic line 66 acts on the main switching valve 62 through the passage 70 and moves the spool to the left (see FIG. 3A), so that the main switching valve is in the first position (FIG. 2). Take the right position). As a result, the high pressure port A communicates with the supply / discharge line 54, and the low pressure port B communicates with the remaining three supply / discharge lines 56, 58, 60. Conversely, when high-pressure hydraulic oil is introduced into port B in order to move the vehicle backward, since port A is low pressure, auxiliary switching valve 68 assumes the right position as viewed in FIG. Then, the hydraulic line 66 is connected to the passage 72 via the auxiliary switching valve 68. In this case, the pilot pressure in the hydraulic line 66 acts on the main switching valve 62 through the passage 72 and moves the spool to the right (see FIG. 3B), so that the main switching valve is in the second position (see FIG. Take the left position). As a result, the high pressure port B communicates with the supply / discharge line 60, and the low pressure port A communicates with the remaining three supply / discharge lines 54, 56, 58.
[0020]
As can be understood from the above description, unlike the conventional cam motor, the cam motor of the present invention has a high-pressure hydraulic oil within the cam motor regardless of which port A or B is in a high pressure state in the small capacity mode. The three through holes of the valve plate are always in a high pressure state through one supply / discharge line, and the occurrence of a difference in efficiency when the cam motor rotates left and right is prevented not only in the large capacity mode but also in the small capacity mode. Therefore, when the cam motor of the present invention is employed as a vehicle driving motor, there is no difference between the forward speed and the reverse speed, and there is no difference in output torque during left-right rotation. In addition, the cam motor of the present invention can be used as a traveling motor for both the left and right sides of the vehicle, and in this case, the stock of separate cam motors configured to match the asymmetrical arrangement of the piping and the left and right arrangement, which has been necessary in the past, is no longer necessary. Compared with the conventional cam motor, the labor of inspection and maintenance can be saved.
[0021]
The present invention has been described for a two-speed multi-stroke radial piston motor having six cam peaks, eight pistons and twelve through holes in the valve plate. However, the number of cam peaks is greater than six. The present invention can be similarly applied to a radial piston motor having more than eight pistons. In this case, the number of through holes in the valve plate is equal to the number of cam ridges × 2, but the mutual angle interval of the corresponding through holes and the number of through holes leading to the four passages 54 to 60 are also different from the above. However, those skilled in the art can easily change the design.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a two-speed multi-stroke radial piston motor incorporating a switching valve device of the present invention.
FIG. 2 is a hydraulic circuit diagram for explaining the operating principle of the two-speed multi-stroke radial piston motor shown in FIG. 1, showing the relationship between the valve plate and the switching valve device of the present invention.
FIG. 3A is a schematic diagram showing the operating state of the spool of the main switching valve of the present invention.
FIG. 3B is a schematic view showing an operating state of the main switching valve of the present invention, and is a view showing a state in which the spool is urged in the direction opposite to that in FIG. 3A.
FIG. 4 is a schematic cross-sectional view of a conventional two-speed multi-stroke radial piston motor.
5 is a schematic diagram showing a displacement mechanism of the two-speed multi-stroke radial piston motor shown in FIG.
6 is a schematic diagram showing the operation principle of the 2-speed multi-stroke radial piston motor of FIG. 4, and is a diagram showing the relationship between the valve plate and the 2-speed switching valve.
FIG. 7A is a view showing a state in a large capacity mode of a switching valve of a conventional two-speed multi-stroke radial piston motor.
FIG. 7B is a diagram showing a state of the switching valve of the conventional two-speed multi-stroke radial piston motor in the small capacity mode, and is a diagram showing a state where the spool is urged in the direction opposite to that in FIG. 7A.
[Explanation of symbols]
10,110 2-speed multi-stroke radial piston motor 24 Push-off mechanism 32, 132 Valve plate 34 Output shaft 42, 142 Switching valve device 54, 56, 58, 60 Supply / discharge line 62 Main switching valve 68 Auxiliary switching valve

Claims (7)

There are provided a cam having a cam surface, a plurality of radial pistons each having a roller adapted to roll relative to the cam surface, and a plurality of bores for receiving the pistons. A retraction mechanism including a cylinder block, a valve plate having a plurality of through holes provided at equiangular intervals in the circumferential direction for sequentially supplying and discharging hydraulic oil to and from the piston of the displacement mechanism, and a reciprocating motion of the piston Low-speed, high-torque (large capacity) by communicating with the selected number of through-holes in the valve plate, the means for taking out the shaft as rotational movement, and two hydraulic oil ports that can be selectively switched between high pressure and low pressure In a two-speed radial piston motor having a switching valve device that switches operation between a mode and a high-speed low-torque (small-capacity) mode, the switching valve device includes: A main switching valve capable of communicating with one hydraulic oil port and having at least four separate supply / discharge lines leading to a selected number of through holes in the valve plate, and provided in cooperation with the main switching valve; When one of the two hydraulic oil ports is set to a high pressure, a hydraulic pilot source is applied to the main switching valve accordingly, and the high pressure hydraulic oil port communicates with only one of the supply / discharge lines of the main switching valve. A two-speed radial piston motor comprising an auxiliary switching valve operable to operate. The two-speed radial piston motor is of a multi-stroke type, the cam is a ring-shaped cam having an inner cam surface, and the cylinder block is a single cylinder provided inside the cam. A two-speed radial piston motor comprising a block. Plural pistons comprising rollers provided radially in a cam ring having an inner cam surface, each of which is adapted to roll relative to the inner cam surface in a engaged state. A displacement mechanism portion including a single cylinder block provided with a plurality of bores for storing a plurality of bores, and a plurality of displacement mechanisms provided at equal angular intervals in the circumferential direction for sequentially supplying and discharging hydraulic oil to and from the piston of the displacement mechanism portion A valve plate with a through hole, means for extracting the reciprocating motion of the piston as a rotational motion of the shaft, and two hydraulic oil ports that can be selectively switched between a high pressure state and a low pressure state through a selected number of passages in the valve plate. 2-speed multi-straw having a switching valve device for switching operation between a low speed high torque (large capacity) mode and a high speed low torque (small capacity) mode by communicating with the hole In the radial piston motor, the switching valve device is capable of communicating with the two hydraulic oil ports and has at least four separate supply / discharge lines communicating with a selected number of through holes in the valve plate. When one of the two hydraulic oil ports is set to a high pressure, the pilot pressure from the hydraulic pilot source is applied to the main switching valve in accordance with this and the high pressure operation is performed. A two-speed multi-stroke radial piston motor having an auxiliary switching valve operable to communicate an oil port with only one of the supply / discharge lines of the main switching valve. When one of the two hydraulic oil ports is at a high pressure, the main switching valve causes the one hydraulic oil port to communicate with one of the four supply / discharge lines by the pilot pressure and the remaining one. A first position where the three supply / discharge lines communicate with the other low-pressure hydraulic oil port, a neutral position taken when the pilot pressure is not generated, and a case where the other hydraulic oil port is high-pressure, A second position where the other hydraulic oil port communicates with one supply / exhaust line other than the one supply / exhaust line and the remaining three supply / exhaust lines communicate with one of the low-pressure hydraulic oil ports by the pilot pressure. 4. A two-speed multi-stroke radial piston motor according to claim 3, further comprising a spool that can move between the first and second multi-stroke radial piston motors. 5. The second speed according to claim 4, wherein the main switching valve has pilot chambers on opposite sides of the spool, and the pilot chambers are connected to the hydraulic pilot source via auxiliary switching valves, respectively. Multi-stroke radial piston motor. 5. The two-speed multi-stroke radial piston motor according to claim 4, wherein each of the four supply / discharge lines communicates with a through hole located at a predetermined angular interval of the valve plate. The two-speed multi-stroke radial piston motor according to claim 6, wherein the valve plate is provided with twelve through holes, and the angle is 120 °.

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