JP2004190652A - Rotary fluid energy converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute couple of forces in a simpler way than ever before while reducing the size and weight of a device, reducing its cost, realizing its long life, and improving starting torque efficiency, offsetting a bearing load of a radial cylinder/static pressure type fluid pump or a motor and reducing a load of a rolling bearing by constituting the couple of forces with fluid pressure. <P>SOLUTION: A plurality of static pressure pads 6 are provided on an inside face of a front case 5 along a half circumference on a high pressure side of a pintle 1, and the static pressure pads to which pressure of a cylinder 21 of the half circumference is introduced are brought into slide contact with a spherical outside surface of a polygon ring 4 to constitute the couple of forces. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotary fluid energy converter used as a hydrostatic fluid pump or motor.
[0002]
[Prior art]
The inventor of the present invention has previously proposed a rotary fluid energy converter (see Japanese Patent Publication No. 7-54113). This energy converter has a fitting hole formed at the center of each side of a polygon ring (torque ring). The load on the support bearing of the torque ring is reduced by fitting a hydrostatic bearing shoe into each hole and forming a couple on each side of the polygon ring.
[0003]
[Problems to be solved by the invention]
In the conventional rotary fluid energy converter, since the hydrostatic bearing shoes are inserted into the outer surface of the polygon ring for each side, there are many disadvantages as described below.
1) Since the static pressure bearing shoe receives a large centrifugal force of 2000 G or more during high-speed operation, the static pressure balance is lost, and the pv value on the outer surface of the shoe becomes large, and seizure becomes easy.
2) Therefore, it is necessary to reduce the weight of the shoe, and it is inevitable to use a light alloy as the material. However, there is no light alloy having a very good sliding bearing performance.
3) It is necessary to apply a molybdenum disulfide film coating on the shoe surface in order to prevent burning inevitably, which causes an increase in cost.
4) The shoes are fitted so as to be tiltable, and the static pressure balance must be slightly overbalanced for the above reasons. Therefore, it is difficult to suppress the leakage flow rate from the individual static pressure bearings, and the number of shoes is large. 5) The inner surface of the front case, which is to be in sliding contact with the outer end surface of the shoe to form the hydrostatic bearing, must satisfy the surface roughness and surface hardness required for a high-speed sliding surface and the concave spherical shape accuracy. However, it is necessary to fit a separate lining on the inner surface of the front case.
6) In order to finish the inner concave spherical shape of the quenched steel lining ring, a long-time operation by a special lapping device is required, which causes an increase in cost.
7) Since the shoe repeatedly and frequently switches between high pressure and low pressure every half rotation, it is disadvantageous in terms of durability such as a ring seal of the shoe.
8) Since the shoe is tiltably fitted and held in the fitting hole only by the friction of the ring seal, sufficient care must be taken so that the shoe does not fall off during assembly.
9) The processing of the shoe fitting hole of the polygon ring is also complicated and requires precision, which causes an increase in cost and reduces the rigidity of the polygon ring.
10) The processing of the shoes is also complicated and requires high precision, and the number of required shoes is large, which causes an increase in cost.
A rotary fluid energy converter that eliminates the above-mentioned drawbacks, reduces the leakage loss of the hydrostatic bearing while making use of the features of the couple type, and facilitates machining and assembly.
[0004]
The present invention relates to two groups of radial forces outwardly applied to each inner plane of the polygon ring by each cylinder pressure, a radial force by a half-circle cylinder on the pintle high-pressure side and a radial force by a half-circle cylinder on the pintle low-pressure side. The above-mentioned problem is to be solved by collectively canceling the radial load.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the rotary fluid energy converter of the present invention, as shown in FIG. 1, a fitting hole at the center of each side of the polygon ring 4 is eliminated, and the outer peripheral surface thereof is formed into a spherical smooth surface. A plurality of hydrostatic pads are arranged on the inner surface of the front case covering the polygon ring on the pintle high pressure port side half circumference, and the pressure of the high pressure port is introduced to the pads.
[0006]
Since the bowl-shaped polygon ring is cantilevered, the number of pads arranged on the high pressure port side half-circle is two or more even for small equipment in order to keep the distortion below a certain value in consideration of the rigidity of the edge of the bowl. It is necessary to select and arrange a plurality of pads at a position where the distortion at the opening end of the ring is sufficiently small.
As described above, by properly arranging the static pressure pad on the outer surface of the polygon ring instead of the shoe and slidingly contacting the same, all of the disadvantages of the ten items can be solved.
In particular, when used in a constant pressure source system proposed by the present inventor (an advanced energy saving system capable of recovering and reusing the energy of movement and position), one of the two ports is always at a low pressure, so that the low pressure port side half circumference is used. The static pressure pad is unnecessary, and the number of pads is reduced to half, which is more advantageous.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described based on examples with reference to the drawings.
FIG. 1 shows an embodiment in which the present invention is applied to a variable pump / motor having 7 cylinders. FIG. 1 is a sectional view taken along a line 1-1 in FIG. 2 shows a view taken in the direction of arrow 2-2 in FIG. 1 (excluding the cylinder block 2). In the case of the variable type, the pintle 1 is guided by a trapezoidal groove provided in the rear case 7 and can move in a direction perpendicular to the plane of FIG. Is tapered (frusto-conical). Since the center axis of the cylinder is substantially perpendicular to the tapered surface, the outward radial force that each side of the inner surface of the polygon ring 4 receives from the seal bush 3 is inclined toward the input / output shaft.
[0008]
Since the number of cylinders is 7, three or four seal bushes, which are half of the high pressure side, take turns and become high pressure in accordance with the rotation, and press the inner surface of the polygon ring 4.
The force vector illustrated by Fs3 indicates the resultant force of the outward radial forces received on three sides of the half circumference of the polygon ring (three seal bushes become high pressure), and the force vector illustrated by Fs4 indicates (the four seal bushes become high pressure). ) Shows the resultant force of the outward radial forces received on the four sides of the ring half circumference. Therefore, as shown in the enlarged view in the upper part of FIG. 1, the radial component forces of Fs3 and Fs4 are equal, but the axial component force is 3 to 4.
[0009]
The outer peripheral surface of the polygon ring 4 is finished into a spherical smooth surface, and the hydrostatic pad 6 in the shape of a cup is held toward the center of the spherical surface by a holding hole provided in the front case 5. Lightly pressed against the surface. Then, a port pressure communicating with the cylinder on the static pressure pad side is introduced to the back of the static pressure bearing 6.
[0010]
Fig. 2 shows the couple variable pump / motor viewed from the opposite shaft end side with the rear case 7, the pintle 1 and the cylinder block 2 removed, as in the case of use in a constant pressure source system or the like. The variable pump / motor in which the static pressure pad on the always lower pressure side (right half circumference in the figure) is omitted is shown.
The hydrostatic bearings 6 and 6 'fit into the inner diameters of a pair of holding holes provided in the front case, and the position, direction and inner diameter of the holding holes are the resultant of the force obtained by multiplying the area by the above-described introduction pressure (FIG. 1). Fp) is set to cancel the average force vector of Fs3 and Fs4 in FIG.
[0011]
【The invention's effect】
Explaining the enlarged display at the top of FIG. 2, since FIG. 2 is viewed in the axial direction, the length of the force vector represents the magnitude of the component force in the radial direction (perpendicular to the axis).
Therefore, the length of the force component in the radial direction of the force vector by which the seal bush presses the polygon ring from the inside is the same when three are high and four are high, and this is indicated by Fsr.
As shown by the broken line, Fsr frequently fluctuates with rotation at an angle width of (90 ° / number of cylinders) to both sides from the average center direction, but fluctuates due to inertia of the load in practical use. Is absorbed, so that the broken line can be ignored, and it can be considered as an average central vector.
[0012]
Therefore, a couple force (a pair of forces having the same magnitude and offset in opposite directions = pure rotational force) is constituted by the radial component force Fpr of the force vector Fp and the above-described Fsr. The reversal of the rotational force corresponds to the magnitude of the eccentricity E of the pintle 1 and the sign of the eccentric direction.
This is the torque of the input / output shaft (integral with the polygon ring), but since it is a couple, almost no load (other than external force) is applied to the bearing supporting the input / output shaft.
[0013]
One force Fsr constituting the couple is due to the force of the high pressure liquid in the hydraulic pocket on the outer end face of the seal bush 3 pushing the polygon ring from the inside, and the other force Fpr is the force on the inner end face of the static pressure pad 6. This is due to the force of the high-pressure liquid in the hydraulic pocket pushing the polygon ring from the outside.
Therefore, unlike the conventional pump / motor, there is no place where the solid pushes the solid in the process of generating the torque, and the couple gives a pure rotational force to the input / output shaft. It is called a Fluid Force Couple pump / motor.
[0014]
From another point of view, the FFC pump / motor has a conventional pump / motor because all the internal components are floating in the hydraulic fluid while maintaining the static pressure balance, and there is no place to slide while pressing strongly. Compared to motors, it basically has the following many features.
A) The load on the rolling bearing is small.
Therefore, 1) small size and light weight 2) low cost 3) low noise B) all internal parts are pressure balanced,
Therefore, 4) low friction loss and high mechanical efficiency 5) no stick-slip at start-up 6) no lubrication of hydraulic fluid is required 7) high pressure and high speed operation is possible 8) durable and reliable C) seal Since no radial force is applied to the bush, the only remaining gap that can be mounted on the piston ring is the gap due to the difference in diameter between the cylinder and piston (all other parts are tightly sealed).
Therefore, 9) low leakage loss and high volumetric efficiency 10) low viscosity liquid can be used 11) small decrease in efficiency at high temperature D) Variable displacement control is pintle displacement control (instead of conventional angle control) .
Therefore, 12) good control linearity 13) good control responsiveness E) The oil path at the bottom of the cylinder is wide, and 14) the decrease in efficiency during high-speed operation is small.
The device of the present application occupies a major position in so-called hydraulic components, and is a type of variable pump / motor that is expected to become more and more important from the viewpoint of energy saving.
If the ten drawbacks based on the shoe are eliminated by the improvement of the present application, the features of the above-mentioned fourteen FFC-type variable pumps / motors which are not found in the conventional variable pump / motor can be recognized, and the FFC type variable pump / We believe that the widespread use of motors will contribute to energy saving and upgrading of hydraulic systems.
[0016]
If one static pressure pad is provided on the front case at the position of the resultant force Fp of the inward force vectors of the plurality of static pressure pads, the same effect can be obtained (theoretically and qualitatively). For this reason, the volume and weight of the product are increased, and the greatest features of the small size, light weight and high responsiveness as compared with the electric drive are weakened. (See Fig. 4)
1) In order to suppress the distortion of the polygon ring 4, it is necessary to increase the radius of the spherical surface of the outer surface, and the inertia of the rotating part increases.
2) The inner diameter of the front case 5 increases as the outer diameter of the polygon ring increases.
3) The pressure receiving area of the static pressure pad 6 is also slightly less than twice (in the case of two pads) and the pad becomes large. 4) As 3), both the depth and the diameter of the static pressure pad holding hole increase.
5) The thickness of the front case 5 increases accordingly from the viewpoint of strength.
6) It is necessary to provide a holding hole (large in both diameter and depth) in the direction of the resultant force vector of a plurality of pads (see FIG. 1Fp), and in the case of a flange mounting type, extend the front case and the input / output shaft in the shaft end direction. Will be.
[0017]
[Brief description of the drawings]
FIG. 1 is an axial cross-sectional view of a variable displacement hydraulic pump / motor using the present invention, and is a drawing for explaining offset and reduction of a rolling bearing load by a hydrostatic pad.
FIG. 2 is a drawing corresponding to a view taken in the direction of arrow 2-2 in FIG. 1 and explaining that the rotational force of a variable displacement hydraulic pump / motor using the present invention is due to couple force.
[Explanation of symbols]
1. Pintle 2. Cylinder block 21. Cylinder 3. Seal bush 4. Polygon ring 5. Front case 6. Static pressure pad 7. Rear case Fs: Outward force vector of seal bush Fp: Combined force of inward force vector of static pressure pad FIG. 3 is a drawing showing a case where a static pressure shoe is used for comparison.
[Explanation of symbols]
1. Pintle 2. 2. cylinder block, Seal bush,
4. Polygon ring, 5. Front case 6. 6. static pressure shoe, FIG. 4 is a view showing a case where one static pressure pad is used for comparison with FIG.

Claims (1)

A cylinder block (2) that engages with the pintle (1) and radially forms a plurality of cylinders (21); and a seal bush (3) that fits into each cylinder of the cylinder block and has a flat outer end surface. A polygon ring (4) whose end face is in close contact with its inner flat surface, and a casing that supports the pintle and covers the polygon ring, wherein the polygon ring is rotatably supported around its central axis. In the converter,
A plurality of static pressure pads (6) (6 ') held by the casing are provided, and they are slid into contact with the outer surface of a half circumference of the polygon ring corresponding to the high pressure port of the pintle. A rotary fluid energy converter characterized by forming a couple by a resultant force of an outward radial force received from a seal bush on a half circumference of a pintle on a high pressure side, thereby substantially canceling a bearing load of a polygon ring.

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