JP3800246B2 - Radial piston pump - Google Patents

Description

[0001]
[Industrial application fields]
The present invention includes a plurality of cylinders arranged at predetermined angular intervals around a drive shaft, a plurality of pistons slidable in the cylinders and having end surfaces radially inward, and eccentric portions of the drive shaft The present invention relates to a radial piston pump provided with a cam that can be rotated at the same time.
[0002]
[Prior art]
A pump of the type described above is described in European Patent Publication No. 304743, which comprises three pistons arranged radially and supported on a cam by a spring. When the drive shaft rotates, the piston moves with respect to the cam surface, wears due to friction between the two, and generates heat.
[0003]
[Problems to be solved by the invention]
The object of the present invention is to provide a radial piston pump of the kind described above that is very simple and reliable, in which the friction is reduced as much as possible and absorbed accordingly. .
[0004]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, in the present invention, a plurality of cylinders (12) disposed at a predetermined angular interval around the drive shaft (18), and slidable within each cylinder (12). A plurality of pistons ( 140 ) having end faces (180) radially inward, a cam (288) rotatable at an eccentric part (24) of the drive shaft (18), and a plurality of pads ( 162 ), , each of said pads (162), the end face of the inner (180), to each of the pads (162) by acting on the piston (140) via a return spring (166) is holding means (186) This Abuttingly attached to one of the pistons ( 140 ), the pad ( 162 ) also engages a flat portion (232) of the cam (228), and the pad ( 162 ) Flat A plurality of pads such that a frictional resistance (Q) between the carrier part (232) is oriented perpendicular to the drive shaft (18), and during operation, the pad ( 162 ) is The holding means ( 186 ) for preventing separation from ( 140 ) and the pad ( 162 ) are provided to accommodate the radially inner end face ( 180 ) of the piston ( 140 ). A seat ( 185 ), the pad ( 162 ) is circular, and a shoulder ( 198 ) is formed, and the holding means ( 186 ) is attached to the pad ( 162 ). is deposited and provided with a retaining disc that is coupled axially (186) to the piston (140), the retaining disc (186) has at least one locking engaging said shoulder (198) (188) comprises a, and the said retaining disc (186), said central opening for attaching the piston (140) (192) is formed, said piston (140), at least the central opening In the portion adjacent to the portion (192), the flat surface (190) of the holding disk (186) is elastically deformed and press-fitted inside the central opening (192), so that the flat surface (190) A radial piston pump is provided in which the inner periphery (194) of the piston is bent toward the front end face (180) of the piston (140).
[0005]
【Example】
1 and 2, the radial piston pump 10 according to the present invention includes three cylinders 12-1, 12-2, and 12-3, and the central axis 41 of each cylinder has an angle of 120 °. Arranged at intervals. As will be described in detail below, a piston 40 is slidably disposed in each cylinder 12, and the center surface 14 of the cylinder chamber of the cylinder 12 intersects the center axis 16 of the drive shaft 18 of the pump 10. .
The drive shaft 18 has an eccentric portion 24 between two sliding bearings (friction bearings) 20 and 22. The eccentric portion 24 is eccentric with respect to the central axis 16 by a distance ME. The eccentric portion 24 has a sliding bearing (friction bearing) 26, and is configured to be rotatable inside the central hole 30 of the eccentric cam 28 by the bearing. The eccentric cam 28 is formed in a substantially polygonal shape by a side surface having three flat portions 32-1, 32-2, and 32-3. The flat portion is perpendicular to the central axes 41 of the cylinders 12-1, 12-2, and 12-3, and forms an angle α of 60 °.
The eccentric cam 28 is maintained at a constant angular position shown in FIG. 2 by the piston 40 of the pump 10. As the drive shaft 18 rotates, the center 34 of the eccentric cam 28 rotates along a circular path of radius ME about the central axis 16 and each flat portion 32 of the eccentric cam 28 is relative to its own plane. In parallel with each other, along a circular path, the piston 40 operates periodically in each cylinder 12.
[0006]
A cylindrical insert 36 having a guide hole 38 coaxial with the central shaft 41 is attached inside each cylinder 12, and each piston 40 is configured to slide in the guide hole 38. A radially outer end face of the piston 40 forms a variable displacement pump chamber 42 in the guide hole 38, and the pump chamber has an inlet 44 for accommodating the one-way valve 46 and an outlet 48 for accommodating the one-way valve 50. And have.
The inlet 44 is connected to a preload pump 54 having a higher capacity via a path 52, and the preload pump 54 is connected to the tank T, and a pump such as a bearing surface or a valve body is connected to the tank T via the path. Coolant is supplied to the ten most thermally stressed parts (not described in detail). The outlet 48 of each pump chamber 42 is in communication with a path 56 connected to a pressure relief valve 58. The stop means 58a of the pressure relief valve 58 receives a pressure that is varied by the electromagnetic device 60 to regulate or control the maximum fluid pressure at the outlet 48.
[0007]
A contact surface 80 is formed on the radially inner end surface of the piston 40 (see FIG. 3), and the corresponding contact surface 80 is in contact with the pad 62 disposed on the flat portion 32 of the eccentric cam 28. . The pad 62 preferably has a circular cross section with a diameter slightly smaller than the inner diameter W (see FIG. 1) of the inner surface 64 of the cylinder 12 and a recess for the insert 36 is formed.
The piston 40 is urged radially inward by an urging means comprising a pre-loaded compression coil spring 66 (shown by a one-dot chain line), and the compression coil spring 66 abuts against a shoulder 68 of the insert 36. It touches. Thus, the piston 32 follows the eccentric operation of the flat portion 32 of the eccentric cam 28 and operates radially inward to expand the volume of the pump chamber 42.
[0008]
When the eccentric cam 28 operates eccentrically, an acting force Q perpendicular to the central axis 41 is generated by the frictional resistance between the eccentric cam 28 and the pad 62, and the pad 62 causes the pad 62 to be eccentric. Reciprocally slide relative to the flat portion of the cam 28. Therefore, measures are required to ensure the axial alignment of the pad 62 and the piston 40 during the pump cycle.
According to the present invention, the alignment of the pad 62 and the piston 40 and, as a result, absorption of frictional resistance perpendicular to the plane of FIG. 1 is achieved by each piston 40 and the guide hole 38 of the insert 36. As shown in FIG. 3, the pad 62 includes a circular disk 70 formed integrally with the sleeve 72, and the inner diameter of the sleeve 72 is larger than the outer diameter of the guide disk 74 attached to the piston 40. Is also slightly larger.
More specifically, the guide disk 74 is attached to an annular groove 76 formed in the vicinity of the inner end face of the piston 40, so that the guide disk 74 is fixed to the piston 40 in the axial direction to support the coil spring 66. Act as a part. The annular groove 76 is formed to the minimum necessary depth in order to minimize the decrease in rigidity of the piston 40 as much as possible.
[0009]
The disk 70 of the pad 62 is slidably engaged with the flat portion 32 of the eccentric cam 28 and is supported in parallel with the sliding surface 82 to support the contact surface 80 of the piston 40. A surface 78 is formed.
The gap S between the guide disk 74 and the inner surface of the sleeve 72 is set to a size that does not adversely affect the operation of the pad 62. The length of the sleeve 72 is twice that of both eccentric MEs so that the sleeve 72 always surrounds the piston 40 in the entire stroke of the piston 40.
Since the pads 72 are independent, they may be separated by the action of the coil spring 66. The sleeve 72 thus acts as a retaining means that prevents the pad 62 from separating from the piston 40. Even when the piston 40 stops at the top dead center (the top of FIG. 1) of the guide hole 38 of the insert 36, the separation of the pad 66 is prevented.
[0010]
According to the embodiment of FIG. 4, the pad 162 comprises a circular disk and has a circular support surface 182 that engages the flat portion of each eccentric cam. The surface of the pad 162 opposite to the support surface 182 that houses each piston 140 is a solid, smooth outwardly facing cylinder. The front surface 180 of the piston 140 abuts against the bottom surface 185 of the blind hole 184, and the transverse acting force Q is transmitted to the piston 140 by the pad 162 through the side surface of the blind hole 184. The piston 140 is accurately guided into the guide hole (see FIG. 2) of the insert 36 of each cylinder 12.
In order to prevent separation between the piston 140 (see FIG. 4) and each pad 162, it comprises a holding means, preferably comprising a substantially elastic holding disk 186, having a clamping part 188 formed by a sleeve. Yes. Due to the conical side of the pad 162, the bent end of the sleeve 188 is locked to the shoulder 198 of the pad 162.
[0011]
The holding disc 186 is formed with an elastic flat portion 190 having a circular seat 196 for supporting the spring 166, and the flat portion 190 is provided to attach the holding disc 186 to the piston 140. Yes. For this purpose, the flat portion 190 is formed with a central opening 192 having a diameter smaller than the diameter of the piston 140. When the piston 140 presses the central opening 192 inward, the inner peripheral part 194 adjacent to the opening 192 of the flat part 190 is deformed or bent, and a preload is provided.
During operation of the pump, the eccentric cam acts on the pad 162 via the support surface 182, and the pad 162 performs the operation of the eccentric cam via the bottom surface 185 of the blind hole 184. Transmit to surface 180. As a result, the piston 140 moves upward in FIG. The return stroke of the piston 140 is controlled by a spring 166 acting on the holding disk 186.
The flat portion 190 of the holding disk 186 is attached to the piston 140 so that the pressure applied to the surface of the piston 140 by the central opening 192 is increased by the action of the spring 166 applied to the flat portion 190. This ensures safety against separation of the piston 140 and the pad 162.
[0012]
FIGS. 5-7 illustrate an embodiment similar to FIG. 4, in which the pad 262 of each piston 240 has a circular support surface 282 that engages a flat portion 232 of the cam 228. It has. The pad 262 is formed with a blind hole 242 in which each piston 240 is accurately engaged, and the contact surface of the piston contacts the bottom surface of the blind hole 284. The acting force perpendicular to the central axis 241 of the piston 240 is absorbed by the coupling between the piston 240 and the blind hole 284.
In this case, in order to prevent the pad 262 and the piston 240 from being separated, an elastic disk or a convex washer 286 having a plurality of locking arms 288 parallel to the central axis 241 is provided. Each locking arm 288 is formed with an inwardly bent tab 288 a that engages the shoulder 298 of the pad 262. A central hole 292 is formed in the washer 286, and the piston 240 is inserted therein. The inner periphery of the center hole 292 is bent outward (upward in FIG. 5) so as to form a convex angle (convex angle), and a collar 294 is formed.
The washer 286 is axially fixed to the piston 240 by a fixing ring 299 having a circular cross section, and the fixing ring 299 is accurately held in an annular groove 276 formed at the inner end of the piston 240. The depth of the annular groove 276 is set such that the fixing ring 299 protrudes from the side surface of the piston 240 and the collar 294 of the washer 286 is engaged and fixed to the protruding portion of the fixing ring 299.
[0013]
FIG. 5 shows the piston 240 at top dead center. The suction stroke of the piston 240 is controlled by a spring 266 supported by a washer 286. Since the collar 294 and the fixing ring 299 are coupled, the piston 240 is pulled radially inward by the washer 286 when the flat portion 232 of the cam 228 is displaced. For this purpose, there should be no gap between the pad 262 and the piston 240. This is easily achieved by the pad 262 by the slightly preloaded tab 288a of the locking arm 288.
As shown in FIGS. 6 and 7, the washer 286 is easily formed by a forming die. The flat portion of the washer 286, the collar 294, and the locking arm 288 are formed simultaneously. The locking arms 288 are formed at equiangular intervals around the washer 286. The washer 286 is formed with a protruding portion 297 that protrudes leftward in FIG. 7, and a spring 266 is supported by the protruding portion 297 so that the angular position of the spring 266 is fixed.
The collar 294 is bent upward in FIG. 7 so that a radius R is formed on a surface facing the fixing ring 299, and the collar 294 causes the fixing ring 299 when the pad 262 is attached to the piston 240. Engage precisely with the protruding surface.
[0014]
To assemble the washer 286 shown in FIGS. 5-7, first, the fixing ring 299 is attached to the annular groove 276 of the piston 240, and then the piston 240 is mounted on the washer 286 until the collar 294 contacts the fixing ring 299. The central opening 292 is inserted. Then, the locking arm 288 is bent in the radial direction, and the tab 288a slides along the conical side surface 261 of the pad 262 so that the tab 288a engages with the shoulder 298 with a predetermined preload. The pad 262 is pressed against the inside of the washer 268. The assembly thus formed is inserted into the guide hole 238 of each pump cylinder.
[0015]
【The invention's effect】
The advantages of the radial piston pump according to the present invention will be described in detail below. First, the contact surface of the pad on the cam is increased with respect to a predetermined piston diameter, the specific pressure is reduced, and a forced lubrication device is not required. Secondly, the coupling between the piston and the pad transmits the transverse acting force on the pad directly to the piston, thus eliminating the stress resulting from concentration at the coupling. Third, the life of the pump is extended because the gap between the various elements is compensated. Fourth, the manufacturing cost is reduced because the precision of machining of the components of the pump is not required.
[0016]
It will be apparent to those skilled in the art that the embodiments of the present invention can be modified without departing from the scope of the claims of the present invention. For example, in the embodiment of FIG. 4, the holding disk 186 may be crimped by flexible tabs separated by radial openings. A groove for positioning the spring 166 in the radial direction may be omitted. The sleeve 188 of the retaining disk 186 formed to be locked to the shoulder 198 of the pad 162 may be formed to engage other shapes, for example, the annular groove of the pad 162.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a radial piston pump according to a first embodiment of the present invention.
2 is a schematic cross-sectional view (left side in FIG. 2) along the arrow line IIA-IIA in FIG. 1, and a schematic side view as viewed in the direction of arrows IIB-IIB.
FIG. 3 is an enlarged detail view of a portion indicated by III in FIG. 2;
FIG. 4 is a partially enlarged sectional view of a radial piston pump according to a second embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view of a radial piston pump according to a third embodiment of the present invention.
6 is an enlarged front view of the washer of the radial piston pump of FIG. 5. FIG.
7 is a cross-sectional view taken along line VII-VII in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 12 ... Cylinder 18 ... Drive shaft 24 ... Eccentric part 28 ... Eccentric cam 32 ... Flat part 40 ... Piston 62 ... Pad 66 ... Return spring (coil spring)
72 ... Holding means 80 ... Inner end face (contact surface)
140 ... piston 162 ... pad 180 ... inner end face (contact surface)
186: Holding means 228 ... Eccentric cam 232 ... Flat portion 240 ... Piston 262 ... Pad 286 ... Holding means

Claims (5)

A plurality of cylinders (12) disposed at predetermined angular intervals around the drive shaft (18);
A plurality of pistons ( 140 ) slidable within each cylinder (12) and having end surfaces (180) radially inward;
A cam (288) rotatable at an eccentric part (24) of the drive shaft (18);
A plurality of pads (162), that each of the pads (162), an end face of said inner (180), return spring (166) acts on the piston (140) via the holding means (186) Is attached to one of the pistons ( 140 ) so as to abut against each pad ( 162 ), and the pad ( 162 ) is also engaged with the flat portion (232) of the cam (228). A plurality of pads such that a frictional resistance (Q) between the pad ( 162 ) and the flat portion (232) is oriented perpendicular to the drive shaft (18);
The holding means ( 186 ) for preventing the pad ( 162 ) from separating from the piston ( 140 ) during operation;
A seat ( 185 ) provided on each of the pads ( 162 ) to accommodate the radially inner end face ( 180 ) of the piston ( 140 ),
The pad ( 162 ) is circular and has a shoulder ( 198 ) formed;
The holding means ( 186 ) includes a holding disk ( 186 ) attached to the pad ( 162 ) and axially coupled to the piston ( 140 ),
The retaining disk (186) includes at least one locking arm (188) that engages the shoulder (198), and the retaining disk (186) is attached to the piston (140). A central opening (192) is formed for
The piston (140) is elastically deformed on the flat surface (190) of the holding disk (186) at least in a portion adjacent to the central opening (192), and is press-fitted inside the central opening (192). As a result, the inner peripheral portion (194) of the flat surface (190) is bent toward the front end surface (180) of the piston (140). The pad ( 162 ) comprises at least one radial shoulder ( 198 );
The pump according to claim 1, characterized in that the holding disk ( 186 ) is circularly symmetric and elastic so as to be locked to the shoulder ( 198 ). The holding disc (186) is formed with a circular seat (196) for supporting the return spring (166),
The pump according to claim 1, wherein the seat (196) is formed so as to radially arrange the return spring (166).   A cylindrical insert (36) is fitted to the cylindrical inner surface (64) of the cylinder (12), and the insert (36) has a hole (238), and the piston is placed in the hole (238). (140) is slidably guided, and the disk (186) has a smaller diameter in cross section than the inner diameter (W) of the cylindrical inner surface (64), and thus the insert (36). 2. The pump according to claim 1, wherein each of the pistons (140) absorbs the frictional resistance (Q).   The pump according to claim 4, wherein the cylindrical inner surface (64) is formed with a recess for supporting the insert (36).

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