JP3538567B2 - Hydraulic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for controlling a rotational speed between two high and low levels.
The present invention relates to a variable displacement hydraulic motor configured to be switchable between stages.

[0002]

2. Description of the Related Art The variable displacement type hydraulic motor includes:
A plurality of plungers that extend and retract in the direction of the rotation axis are installed in parallel on the rotatable cylinder block along the circumferential direction, and the motor capacity can be switched between two stages by switching the angle of the swash plate facing the tip of each plunger. In addition, an axial plunger type is known in which a speed change piston for pressing the swash plate from the rear side and switching the swash plate angle is provided on one side of the tilting fulcrum of the swash plate.

As shown in the schematic diagram of FIG. 9, the swash plate 19 in the hydraulic motor having the above-mentioned structure is arranged around a fulcrum Y with respect to a bottom wall S3 of the drive chamber D formed by recessing the casing 11. Positioning fulcrum member 2 such as a ball that can be tilted
4 and its tilting fulcrum P
Is displaced with respect to the rotation axis X of the cylinder block 14, and as shown in FIG. 9 (a), when "low speed" is selected, it is disposed so as to be able to move out of the bottom wall S3 of the drive chamber D. When the shifting piston 30 is retracted, the swash plate 19 is tilted in a direction to increase the swash plate angle by the pressure balance between the pressure received from the plunger group 17 and the deviated tilt fulcrum P,
One swash plate back surface S1 is stably received and supported by the bottom wall surface S3 of the motor drive chamber D. When "high speed" is selected, as shown in FIG.
Is driven to protrude, and the other swash plate rear surface S2 is stably received and supported by the bottom wall surface S3 of the motor drive chamber D, so that the swash plate angle becomes small.

When "high speed" is selected, the outer peripheral end T of the swash plate forcibly tilted by the shift piston on the tilt fulcrum P side serves as a receiving fulcrum with respect to the bottom wall surface S3 and becomes a swash plate tilt angle. Is maintained at a predetermined angle, and the outer diameter of the swash plate 19 is set so that the moment around the receiving fulcrum T based on the pressure received from the group of plungers 17 is larger than the moment around the receiving fulcrum T based on the pressure received from the shifting piston 30. Is set.

[0005]

In the variable displacement hydraulic motor having the above configuration, if the motor capacity is increased by increasing the arrangement pitch circle diameter of the plunger group in order to increase the output, at the time of "high speed", The moment around the receiving fulcrum T based on the pressing of the speed change piston 30 becomes larger than the moment around the receiving fulcrum T based on the pressure received from the plunger group 17, and the swash plate 19 rises up around the receiving fulcrum T, swings, and tilts. The board posture becomes unstable.

In this case, when the diameter of the swash plate 19 is increased and the position of the receiving fulcrum T is moved radially outward, the swash plate 1
The moment around the receiving fulcrum T acting on 9 is corrected, and the posture of the swash plate at "high speed" is stabilized.

However, when the diameter of the swash plate 19 is increased, the inner diameter of the drive chamber D accommodating the swash plate and the cylinder block 14 must be increased. Here, if the inner diameter of the driving chamber D is increased without changing the outer diameter of the casing 11, the peripheral wall thickness of the driving chamber D is reduced, and the strength of the casing 11 is reduced. Conversely, if the thickness of the peripheral wall of the driving chamber D is sufficiently ensured, the outer diameter of the casing 11 becomes large, and the entire motor becomes large.

The present invention has been made in view of such a point, and a variable displacement type motor capable of increasing the motor output while ensuring the required strength without increasing the size of the motor as a whole. It is an object to provide a hydraulic motor.

[0009]

Means for Solving the Problems [Structure, operation and effect of the invention according to claim 1]

(Structure) According to the first aspect of the present invention, a swash plate that rotatably supports a cylinder block and receives and supports a plurality of plungers mounted on the cylinder block is provided in a drive chamber provided inside a casing. The swash plate is arranged to be tiltable in the back of the drive chamber, and the motor capacity can be switched in two stages by changing the angle of the swash plate. A hydraulic motor provided with a shifting piston that switches its inclination angle by pressing from above, wherein the radius of the outer peripheral edge of the swash plate on the side opposite to the side where the shifting piston exists is larger than the radius of the other outer peripheral edge. It is characterized by having been done.

(Function) According to the above configuration, the swash plate receiving fulcrum at the time of high speed is similar to the case where the entire swash plate is increased in diameter in order to increase the motor output by increasing the pitch circle diameter of the plunger group. While maintaining a large distance between the swash plate and the speed change piston to maintain a stable swash plate attitude at high speeds, the inner peripheral shape of the drive chamber is set according to the outer shape of the swash plate. In addition, it is possible to sufficiently secure the thickness of the peripheral wall of the drive chamber in a large part in the circumferential direction.

(Effects) Therefore, according to the first aspect of the present invention, it is easy to increase the motor output without increasing the diameter of the entire casing and without reducing the strength of the peripheral wall of the drive chamber. Become.

[Structure, operation and effect of the invention according to claim 2]

(Structure) According to a second aspect of the present invention, in the first aspect of the present invention, a rotating case to which a driving wheel for traveling is attached is loosely fitted to the casing, and is fitted in a space between the casing and the rotating case. With a core type gear reduction device,
The rotary case is configured to be decelerated by a motor output.

(Operation) According to the above configuration, the motor output can be changed without changing the outer shape of the casing. Therefore, a rotating case to be externally mounted on the casing, a gear reduction device incorporating the casing between the rotating cases, and the like are provided. Commonly used hydraulic motors for traveling with different outputs can be obtained.

(Effects) Therefore, according to the second aspect of the invention, traveling hydraulic motors having different outputs can be manufactured inexpensively by increasing the number of common parts.

[0017]

FIG. 6 shows an all-hydraulic backhoe that uses a hydraulic motor M according to the present invention as a traveling motor, and shows a traveling machine base 2 provided with left and right crawler traveling devices 1. A swivel 3 is mounted on the upper part of the swivel 3 so as to be capable of full swiveling.
A driver's seat 5, an operating device 6, and the like are provided. An excavating device 7 is connected to the front end of the swivel base 3 so as to be able to swing left and right. A dozer device 8 is provided at a front portion of the traveling machine base 2. In addition, not only excavation work but also earth removal and leveling work can be performed.

As shown in FIG. 7, the hydraulic motor M is
The crawler belt 1a of the crawler traveling device 1 is driven by being fixedly connected to a track frame 2a provided on the traveling machine base 2 and having a driving wheel 9 bolted to a rotating portion of the hydraulic motor M.

FIG. 1 shows a cross section of the hydraulic motor M. The casing 11 of the hydraulic motor M is provided with a flange portion 11a for connection to the track frame 2a, and a drive chamber D that opens toward the inside of the machine is formed in a recessed manner. Is closed. At the center of the driving chamber D, a rotation support shaft 13 is cross-supported, and the rotation support shaft 13 is mounted on the cylinder block 1.
4 is inserted so as to be relatively non-rotatable and slidable in the axial direction.
The valve block 12 is urged to slide toward the second side.
Is slidably pressed by a valve plate 16 attached to the inner surface of the first plate.

The cylinder block 14 is provided with a plurality (for example, nine) of plungers 17 which can slide and retreat in the direction of the rotation axis at a constant pitch in the circumferential direction. A swash plate 19 for receiving the tip of the group of plungers 17 via a sliding plate 18 is provided.

Pressure oil for normal rotation or reverse rotation is supplied to the valve block 12, and this pressure oil is supplied to the cylinder block 1.
The plunger group 17 is supplied to the plunger 4 and protrudes in a predetermined distribution to press the swash plate 19, and the cylinder block 14 is rotated by a circumferential component of the pressing reaction force. It is to be taken out.

A rotary case 21 having a flange portion 21a for connecting the drive sprocket 9 is fitted on the outside of the casing 11 via a rolling bearing 22. The rotary case 21 is provided between the rotary case 21 and the casing 11. A planetary gear reduction device 23 for greatly reducing the output of the rotary support shaft 13 and transmitting the output to the rotating case 21 in the space formed in
Is incorporated.

In this hydraulic motor M, the output rotation speed is steplessly changed in proportion to the supplied oil amount, and the angle of the swash plate 19 is changed in two steps so that the cylinder block 14 makes one rotation. In this case, the variable displacement type is provided with a function (sub-shift function) of changing the output rotation speed between high and low by changing the amount of oil supplied and discharged by the plunger group 17. explain.

The swash plate 19 is formed in a substantially circular shape when viewed in the axial direction, and is formed in a wedge shape when viewed from the side. The back is formed as a chevron surface having a pair of backs S1 and S2 with the ridge L as a boundary. Here, the ridge L is deviated with respect to the axis X of the rotation support shaft 13, and a pair of hemispherical holes 25 for engaging the spherical locking member 24 is formed on the ridge L. At the same time, a pair of hemispherical holes 26 are formed in the bottom wall S3 of the driving chamber D to engage the locking member 24, and the locking member 24 is formed between the hemispherical hole 25 of the swash plate 19 and the bottom wall S3 of the driving chamber D. By being engaged over the hemispherical hole 26, the swash plate 19 is held at a fixed position and supported so as to be able to swing with the center of the locking member 24 as a tilt fulcrum P.

Here, since the tilting fulcrum P is deviated from the axis X of the rotary shaft 13, the moment around the tilting fulcrum P applied to the swash plate 19 by the pressing force from the plunger 17 group is obtained. The swash plate 19 works in the direction of tilting the swash plate counterclockwise in the figure, and as shown in FIG. 5A, the back surface S1 is stabilized with the bottom wall surface S3 receiving it. When the back surface S1 is received by the bottom wall surface S3 in this manner, a large swash plate angle .theta.1 is provided, and a "low speed" state appears.

On the bottom wall S3 of the drive chamber D, a shift piston 30 for pressing the back surface S1 of the swash plate 19 from the back is provided.
As shown in FIG. 5B, the swash plate 19 is forcibly tilted clockwise in the figure around the tilt fulcrum P, and the other back surface S2 is stabilized in a state of being received by the bottom wall surface S3. In this state where the back surface S2 is received by the bottom wall surface S3, a small swash plate angle .theta.2 is provided, and a "high speed" state appears.

FIG. 8 shows a hydraulic circuit diagram for driving the hydraulic motor M. In the figure, reference numeral 31 denotes a traveling control valve, which is linked with a pair of left and right control levers 32 provided in the operating device 6 to be switched to a mechanical type or a hydraulic pilot type, so that hydraulic oil from a pump P is transmitted. At an arbitrary flow rate to the forward rotation oil passage f or the reverse rotation oil passage r,
The hydraulic motor M can be driven forward (forward) or reverse (reverse) at any speed. Reference numeral 32 denotes a high-pressure selection shuttle valve connected to the forward rotation oil passage f and the reverse rotation oil passage r, and supplies high-pressure hydraulic oil for driving a motor to the speed-changing piston 30. 33 is a shuttle valve 3
A hydraulic pilot type flow path switching valve 34 interposed between the gear 2 and the speed change piston 30 is a pedal operated pilot valve for switching the flow path switching valve 33. Normally, when the pilot valve 34 is not depressed, the speed-changing piston 30 is in the oil discharging state, and the swash plate 19 is in the "low speed" state shown in FIG. While the pilot valve 34 is being depressed, the flow path switching valve 3
3, the shifting piston 30 is driven to protrude by the hydraulic pressure from the high-pressure side of either the forward rotation oil passage f or the reverse rotation oil passage r, and the swash plate 19 is in the "high speed" state shown in FIG. It becomes.

In FIG. 8, reference numeral 35 denotes a counterbalance valve for holding a stopped state, and reference numeral 36 denotes a shockless mechanism for alleviating an impact at the time of starting and stopping. It is incorporated in the valve block 12.

The above configuration is not particularly different from the conventional one, and in the present invention, the swash plate 19 is configured as follows.

That is, as shown in FIG.
9 is formed in a circular shape having a radius R1 and the outer peripheral edge 19a on the side opposite to the side on which the speed change piston 30 is present is partially protruded so that its radius R2 is larger than the radius R1. In this state, the distance between the receiving fulcrum T of the swash plate 19 and the speed change piston 30 is longer than that in the case where the entire swash plate is formed into a circle having the radius R1. In addition, as shown in FIG.
Only the portion corresponding to the large-diameter portion of the swash plate 19 is enlarged in diameter, so that the thickness of the peripheral wall of the driving chamber D at most of the peripheral wall is increased.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a hydraulic motor according to the present invention.

FIG. 2 is a longitudinal sectional front view of a driving room.

FIG. 3 is a rear view of the inclined plate;

FIG. 4 is a perspective view of the inclined plate viewed from the front side.

FIG. 5 is a perspective view of the inclined plate viewed from the back side.

FIG. 6A is a side view schematically showing a low-speed state. (B) Side view schematically showing high-speed state

FIG. 7 is an overall side view of the backhoe.

FIG. 8 is a front view of a hydraulic motor unit.

FIG. 9 is a side view schematically showing a conventional hydraulic motor.

[Explanation of symbols]

9 Drive wheels 11 Casing 14 cylinder block 17 Plunger 19 Swash plate 19a Outer edge 21 Rotating case 22 Gear reducer 30 Speed change piston D Drive room R1 radius R2 radius

Claims (2)

(57) [Claims] A cylinder block is rotatably supported in a drive chamber provided inside a casing.
A swash plate for receiving and supporting a plurality of plungers mounted on the cylinder block is provided in the drive chamber so as to be tiltable inside the drive chamber, and by changing the angle of the swash plate, the motor capacity can be switched to two stages. A hydraulic motor provided with a shift piston that presses a swash plate from the back side to switch its inclination angle to one side of a tilting fulcrum of the plate, wherein the shift piston is located on the opposite side of the swash plate from the shift piston existing side. A hydraulic motor, wherein the radius of the outer peripheral edge is larger than the radius of the other outer peripheral edge. 2. A rotating case to which a driving wheel for traveling is attached is loosely fitted to the casing, and a concentric gear reduction device is interposed in a space between the casing and the rotating case, and the rotation of the rotating case is performed by a motor output. 2. The hydraulic motor according to claim 1, wherein the case is configured to drive the case at a reduced speed.