JP2008298026A - Variable displacement pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable displacement pump capable of facilitating machining of components and reducing cost while inhibiting pulse pressure fluctuation of pump. <P>SOLUTION: Pumping action is provided by volume change of a pump chamber 10 between inner/outer teeth 4a, 5a of an inner rotor 4 and an outer rotor 5 rotated with the inner/outer teeth mutually engaging by a drive shaft 3. A first to third curved surface section 6a to 6c of a holding concave part 6 included in the pump casing 1 are formed by trochoid curves. Tip surfaces 19a to 21a capable of sliding on each curved surface section forms three circular arc shape sliding sections 19 to 21 on an outer circumference of an adjusting ring 7. The adjusting ring is constructed to rotationally sliding contact by receiving pump delivery pressure from a delivery port 14 by first and second sliding contact sections 19, 21 in a manner of resisting spring force of an adjusting mechanism 8. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable displacement pump that supplies lubricating oil pressure to, for example, each sliding portion or transmission of an internal combustion engine for an automobile.

  As this type of conventional variable displacement pump, an inscribed trochoid type described in Patent Document 1 below is known.

  Briefly speaking, suction ports and discharge ports are provided on both sides of the pump casing, and a drive shaft through which rotational force is transmitted from the crankshaft of the engine is disposed through substantially the center. An inner rotor connected to the drive shaft and an outer rotor whose inner teeth mesh with outer teeth on the outer periphery of the inner rotor are rotatably provided in the housing recess formed in the pump casing.

  An adjustment ring that rotatably supports the outer peripheral surface of the outer rotor is provided in the housing recess, and the outer peripheral surface of the adjustment ring is concentric with the center of the outer rotor, and the inner rotor and the It rotates without sliding on the housing recess wall surface concentric with the drive shaft, and the eccentric angle of the inner rotor and outer rotor is rotated and moved by adjusting the rotation angle of the adjustment ring through a predetermined adjustment mechanism. Thus, the pump discharge amount is made variable.

  That is, a gear tooth portion is formed on the inner periphery of the housing recess, while a gear portion that meshes with each gear portion is formed on the outer periphery of the adjustment ring, and the adjustment ring is a spring member of the adjustment mechanism. The pump flow rate is controlled by rotationally moving the inner peripheral gear portion of the housing recess without slipping of the outer peripheral gear portion of the adjusting ring in accordance with the pump discharge pressure via the spring force.

Since the eccentric direction of the outer rotor and the inner rotor can be greatly rotated by the rotational amount and movement angle of the adjustment ring that is small, the rotational movement of the adjustment ring can be controlled by the linear biasing force by the spring member of the adjustment mechanism. It is like that.
JP-A-10-169571 (FIG. 3 etc.)

  However, in the conventional variable displacement pump, since the gear portions are formed on the inner periphery of the receiving recess and the outer periphery of the adjustment ring as described above, it is necessary to process these gear portions with high accuracy. For this reason, such processing work becomes extremely complicated, and the cost is inevitably increased.

In particular, the pump casing is usually made of an aluminum alloy, and requires molding by cutting after molding by aluminum die-casting. To process it into a gear shape, a complicated operation must be performed using a small-diameter tool. As described above, when the processing accuracy of each gear portion is poor, the rotational movement of the adjustment ring is not stable, as shown in FIG. There is a risk of hydraulic pressure fluctuations. Even when machining is performed with high accuracy, the rotational force fluctuates each time the engagement of each gear portion moves to the engagement with the next gear portion. The angle) does not become constant, and as a result, there is a possibility that the hydraulic pressure fluctuation as shown in FIG.

The present invention has been devised in view of the actual state of each of the conventional variable displacement pumps, and the invention according to claim 1 is a pump casing having a suction port and a discharge port and having an accommodation recess. When,
An inner rotor and an outer rotor which are rotatably accommodated in the accommodating recess, and rotate while meshing with each other's inner and outer teeth;
A drive shaft fixed to the center of the inner rotor and applying a rotational force to the inner rotor;
An adjustment ring that is accommodated in the accommodation recess so as to be eccentrically rotatable, and that rotatably supports the outer circumferential surface of the outer rotor on the inner circumferential surface of the ring,
A variable displacement pump that obtains rotation of the adjusting ring and rotationally moves the outer rotor in the eccentric direction of the inner rotor to vary the pump discharge amount,
Set a radius R of an arbitrary length from the center of the inner rotor,
Draw a base circle of radius 2R / 3 for this radius R, set a rolling circle of radius R / 3 that rolls on this base circle,
A line connecting the center of the base circle and the center of the rolling circle as a reference line,
On the extension line of the reference line, set a fixed point for the distance of the eccentric amount in the radial direction of the inner rotor and the outer rotor from the center of the rolling circle to the direction opposite to the center of the base circle,
A trochoidal curve represented by the locus of the fixed point when the rolling circle is rolled on the base circle is created, and a radius r of an arbitrary length is placed on the outer side of the normal line from the point on the trochoidal curve. A trochoidal curve represented by the locus of points that are
Formed in a predetermined position on the inner peripheral surface of the housing recess,
A plurality of sliding contact portions that slide in contact with the curved surface portion formed by the trochoidal curve of the inner peripheral surface of the housing recess are provided on the outer peripheral portion of the adjustment ring so as to project radially outward.
Each of the sliding contact portions is formed in an arc shape of substantially the radius r centered on the position of the radius R from the center of the inner peripheral surface of the ring,
The front end surface of each sliding contact portion is formed so as to be able to slide on the curved surface portion of the housing recess.

  According to the present invention, it is not necessary to form the gear portion on the inner peripheral surface of the accommodating recess and the outer peripheral surface of the adjustment ring, and since the mere arc shape is formed, these processes become easy, and the cost can be reduced. I can plan.

  In addition, the adjustment ring is not rotated by meshing with the gear portion as in the prior art, but the tip of each sliding contact portion is rotated and moved while sliding on the inner peripheral surface of the housing recess through a minute clearance. Therefore, the rotation of the adjustment ring with respect to the increase in hydraulic pressure becomes constant speed, and the occurrence of fluctuations in hydraulic pressure accompanying the increase in rotation of the pump can be sufficiently suppressed.

  Furthermore, since the adjustment ring rotates and moves against the spring force of the adjustment mechanism according to the pump discharge pressure, the pump capacity is reduced when the predetermined discharge pressure is exceeded, and the hydraulic pressure is increased unnecessarily to increase the friction. It becomes possible to suppress sufficiently.

  The invention described in claim 2 is characterized in that three of the sliding contact portions are provided at intervals of approximately 120 ° in the circumferential direction of the adjustment ring.

  According to the present invention, the adjustment ring rotates and moves on the inner peripheral surface of the housing recess of the pump casing while being slidably contacted at three points by the three slidable contact portions. Therefore, stable rotational movement is obtained.

  In the invention according to claim 3, the adjustment ring is urged to a position where one of the sliding contact portions is on the reference line by the pressing mechanism, and the discharge pressure of the pump increases. Accordingly, the discharge contact pressure rotates against the pressing force of the pressing mechanism while the sliding contact portion slides on the inner peripheral surface of the housing recess.

  The invention described in claim 4 is characterized in that a pressure receiving area for receiving the pump discharge pressure of the at least one sliding contact portion is formed in a size different from that of other sliding contact portions.

  According to the present invention, since the pressure receiving area of each sliding contact portion in the rotation direction of the adjustment ring is made different, the pump discharge pressure can be efficiently converted into the rotation force of the adjustment ring with a free magnification. . Thereby, the spring set pressure of the spring member of the adjusting mechanism can be freely set.

  Hereinafter, embodiments of a variable displacement pump according to the present invention will be described in detail with reference to the drawings. This embodiment also shows a trochoid variable displacement pump applied to an oil pump for supplying lubricating oil for an internal combustion engine for automobiles.

  This variable displacement pump is provided at the front end of a cylinder block of an internal combustion engine, etc. As shown in FIGS. 1 to 3, a pump casing 1 whose one end opening is closed by a cover 2, and almost the pump casing 1. A drive shaft 3 penetrating through the center and transmitting rotational force from the crankshaft of the engine; an inner rotor 4 and an outer rotor 5 rotatably housed in a housing recess 6 formed in the pump casing 1; And an adjustment ring 7 that is rotatably accommodated in the accommodating recess 6 and supports the outer peripheral surface of the outer rotor 5 on the inner peripheral surface thereof so as to be freely slidable.

  As shown in FIG. 3, the pump casing 1 is integrally formed of an aluminum alloy material, and an insertion hole 1a for rotatably supporting the drive shaft 3 is formed at a substantially central position. A deformed elliptical accommodating recess 6 is formed. Further, the cover 2 that closes the opening at one end is fixed by six bolts 9, and an adjustment mechanism 8 that urges the adjustment ring 7 in the clockwise direction in the drawing on the right side of FIG. 1. Is provided.

  The drive shaft 3 is driven to rotate in the direction of an arrow (clockwise) in the figure by transmitting a rotational driving force from a crankshaft via a pulley (not shown) provided at one end.

  The inner rotor 4 has a central portion coupled to the drive shaft 2 and six outer teeth 4a formed with a trochoid curve on the outer periphery. The center of the outer rotor 5 is eccentric from the center of the inner rotor 4 by a predetermined amount e, and seven inner teeth 5a formed by a trochoidal curve meshing with the outer teeth 4a are formed on the inner periphery. . Therefore, a pump chamber 10 is formed in a space surrounded by the tooth tip contacts and the tooth bottoms of the rotors 4 and 5, and the volume of the pump chamber 10 changes as the rotors 4 and 5 rotate. Yes.

  In addition, a substantially arc-shaped suction chamber 11 is provided at a lower position in FIG. 1 of the pump casing 1, while a discharge chamber 12 is provided at an upper position opposite to the suction chamber 11. Are provided with a suction port 13 and a discharge port 14 communicating with the suction chamber 11 and the discharge chamber 12, respectively. The suction port 13 communicates with the inside of an oil pan provided at the lower end of the engine body and a strainer via a suction passage (not shown) connected to the suction port 13a, while the discharge port 14 is connected to the discharge port 14a. It is connected to the engine oil main gallery via a discharge passage (not shown) connected to the engine.

  Further, at the opposite end positions of the suction chamber 11 and the discharge chamber 12 of the pump casing 1, a first seal land portion 15 is formed in a portion 10 a where the volume of the pump chamber 10 is substantially maximized. Second seal land portions 16 are respectively formed in the portion 10b that is the smallest on the opposite side. In the present embodiment, the first seal land portion 15 on the maximum volume side is formed in substantially the same shape as that of the pump chamber 10a having the maximum volume.

  In addition, a concave portion is formed at a position corresponding to the suction chamber 11 and the discharge chamber 12 on the mating surface side of the cover 2 with the pump casing 1, and a seal land portion may be formed therebetween.

  The accommodating recess 6 has an angular position of approximately 120 ° in the circumferential direction of the inner peripheral surface thereof, that is, a first curved surface portion 6a substantially corresponding to the maximum volume portion 10a of the pump chamber 10, and the first curved surface portion 6a. Second and third curved surface portions 6b and 6c located at approximately 120 ° in the circumferential direction are each formed by a trochoid curve.

  If the formation procedure of the first to third curved surface portions 6a to 6c is specifically described based on FIGS. 5 and 6, a radius R having an arbitrary length from the center O of the inner rotor 4 is set. A base circle α having a radius 2R / 3 is drawn with respect to the radius R, a virtual rolling circle β having a radius R / 3 rolling on the base circle α is set, and the center O of the base circle α and the virtual circle are set. A line connecting the centers O ′ of the rolling circle β is defined as a reference line J. The reference line J is set so as to pass through the center of the first seal land portion 15, the discharge chamber 12 and the discharge port 14 are positioned at an upper position, and the suction chamber 11 and the suction port are positioned at a lower position. 13 is located.

  On the extended line of the reference line J, a fixed point corresponding to the distance of the eccentricity e in the radial direction of the outer rotor 5 with respect to the inner rotor 4 from the center O ′ of the virtual rolling circle β to the direction opposite to the center O of the base circle α. Set E.

  A curve represented by the locus of the fixed points E and E ′ when the virtual rolling circle β is rolled without sliding on the base circle α is a trochoidal curve γ.

  When the virtual rolling circle β rolls without slipping to the position θ on the base circle α, the rolling circle β rotates by 2θ, so that the fixed point E has rotated by 3θ with respect to the reference line J.

  This can be rewritten as shown in FIG. In other words, a point E that is separated from the center O of the inner rotor 4 by an eccentric amount e is taken, a point T is taken at a position extended by a radius R, and a reference is made in a direction connecting the center point O and the points E and T with a straight line Take line J. From the point E ′ where the point E is rotated by 3θ around the center point O, the locus of the point T ′ having an inclination distance R by θ with respect to the reference line J becomes the trochoid curve γ. Therefore, when the point T is rotationally moved to the point T ′ by the angle θ, the point E is rotationally moved to the point E ′ by the angle 3θ. That is, when the adjustment ring 7 is rotated by an angle θ, the center X of the adjustment ring 7 is rotated by 3θ.

  A trochoid curve-shaped creation curve created by a circle with a radius r centered on the point T ′ on the trochoid curve γ is separated by γ ′, in other words, a radius length r outward from the point T ′ on the normal line. The curved surfaces γ ′ on the trochoid curve represented by the locus of the points are the wall surface shapes of the curved surface portions 6 a to 6 c of the housing recess 6.

  Further, a stopper surface 17 bent substantially in an inverted L shape is continuously formed at a position on the pump rotation direction side of one curved surface portion 6c located on the discharge chamber 12 side.

  On the other hand, as shown in FIGS. 1 and 4, the adjustment ring 7 has a ring main body 18 formed in a substantially annular shape, and the inner peripheral surface 18 a of the ring main body 18 rotates and slides the outer peripheral surface of the outer rotor 5. While being supported freely, three sliding contact portions 19 to 21 whose front end surfaces are in sliding contact with the respective curved surface portions 6a to 6c of the housing recess 6 are integrally projected on the outer periphery in the radial direction.

  The first to third sliding contact portions 19 to 21 are provided at approximately 120 ° in the circumferential direction of the ring body 18 corresponding to the first to third curved surface portions 6a to 6c, and the center of the inner peripheral surface 18a. Respective tip surfaces 19a to 21a are formed in a semicircular shape having a radius r with the distance from X to R as the center.

  That is, the length of the first sliding contact portion 19 to the distal end surface 19a is set such that the center Ta is set at a distance of the radius Ra from the center X of the inner peripheral surface 18a, and a half of the radius ra from the center Ta. The center Tb is set at a distance from the center X to the radius Rb, and the length from the center X to the tip surface 20a of the second sliding contact portion 20 is a semicircular arc having a radius rb. Is formed. The length from the center X to the distal end surface 21a of the third sliding contact portion 21 is set to a center Tc at a distance of the radius Rc from the center X, and is formed in a semicircular arc shape having a radius rc from the center Tc. Yes.

  Then, the first sliding contact portion 19 located on the pump chamber 10a side having the maximum volume is formed with the maximum protrusion amount of the radius Ra, and the second sliding contact portion 20 located on the suction side is a medium radius Rb. The third sliding contact portions 21 that are formed in the protruding amount and are located on the discharge side are formed at the minimum protruding amount with the radius Rc.

  Therefore, the pressure receiving area for the pump hydraulic pressure discharged from the discharge port 14 is larger on the one side surface 19 b of the first sliding contact portion 19 than on the one side surface 21 b of the third sliding contact portion 21.

  Further, when the adjustment ring 7 is rotated clockwise in FIG. 1 on the side portion in the rotation direction of the third sliding contact portion 21, the side surface comes into contact with the stopper surface 17 of the pump casing 1. A restricting protrusion 22 for restricting the above rotational movement is provided integrally with the ring main body 18.

  In addition, the circumferential range of the first curved surface portion 6a of the housing recess 6 described above is set to a predetermined angle (θ−θ1, θ + θ2) in both directions centered on the θ = 0 ° using the e, Ra, and ra. ) And the circumferential range of the second curved surface portion 6b is set from θ = 120 ° to a predetermined angle in both directions counterclockwise using the e, Rb, rb, and further, the third curved surface portion The range in the circumferential direction of 6c is set from θ = −120 ° to a predetermined angle in both directions using e, Rc, and rc.

  Thereby, the front end surfaces 19a to 21a of the sliding contact portions 19 to 21 can be slidably contacted with the curved surface portions 6a to 6c, respectively, through minute clearances.

  Further, an arc-shaped contact portion 23 that rotates the adjustment ring 7 counterclockwise when a plunger, which will be described later, of the adjustment mechanism 8 contacts the position of the second sliding contact portion 20 on the rotation direction side of the adjustment ring 7. Are provided integrally.

  As shown in FIG. 1, the adjusting mechanism 8 includes a cylindrical cylinder portion 24 projecting from the side of the pump casing 1 so as to be inclined, and is slidably held in the cylinder portion 24. The plunger 25 abuts against the abutment portion 23, the plug 26 that closes the open end of the cylinder portion 24, one end elastically contacts the front end surface of the plug 26, and the other end elastically contacts the rear end surface of the plunger 25. The plunger 25 and the spring member 27 that urges the adjustment ring 7 in the clockwise direction in the drawing through the contact portion 23 in contact therewith. Therefore, the first sliding contact portion 19 of the adjustment ring 7 is positioned on the reference line J by the spring force of the spring member 27, the center X of the ring inner peripheral surface 8a is also on the reference line J, and the center of the outer rotor 5 is also It is on the reference line J. That is, the eccentric direction of the outer rotor 5 with respect to the inner rotor 4 is an angle θ = 0 ° in the reference line J direction, and the first seal land portion 15 is also in the reference line J. Accordingly, the positions of the first seal land portion 15 and the maximum volume pump chamber 10a are set to coincide with each other so that the pump discharge amount is maximized.

  Hereinafter, the relationship between the pump discharge pressure and the rotation operation of the adjusting ring 7 in this embodiment will be described with reference to FIGS.

  The space surrounded by the contact points Q1, Q2 between the tip surfaces 19a, 21a of the first and third sliding contact portions 19, 21 of the adjustment ring 7 and the first and third curved surface portions 6a, 6c of the receiving recess 6 is discharged. Since it communicates with the port 14, the pump discharge pressure acts on the upper outer peripheral portion of the adjustment ring 7 located in the space in the figure, and this pump discharge pressure is a straight line connecting the contact points Q1, Q2. The surface pressure P (arrow) acts vertically, and acts as a resultant force F at the center of the contact points Q1, Q2. Since the center X of the adjustment ring 7 is the same as the center point E of the outer rotor 5, the adjustment ring 7 is displaced from the center O of the inner rotor 4 by the amount of eccentricity e. It acts as a force for rotating counterclockwise in the figure with respect to the center O of the rotor 4.

  At this time, the lengths of the first and third sliding contact portions 19 and 21 of the adjustment ring 7 are (Ra + ra)> (Rc + rc), and the first sliding portion 19 is longer. Since the acting position is away from the center O of the inner rotor 4, a larger counterclockwise rotational force is applied to the adjustment ring 7. Further, as shown in FIG. 8, since the pressure receiving area is larger on the one side surface 19 b of the first sliding contact portion 19 than on the one side surface 21 b of the third sliding contact portion 21, it is counterclockwise with respect to the adjustment ring 7. This increases the rotational force.

  Thus, the magnitude of the rotational force generated by the pump discharge pressure acting on the adjustment ring 7 can be controlled by making the values of R + r of the three sliding contact portions 19 to 21 different.

  Next, the operation during engine operation (pump operation) will be described.

  First, after the engine is started (after the pump is started), as the drive shaft 3 rotates, the inner rotor 4 and the outer rotor 5 rotate while meshing with the inner and outer teeth 4a and 5a. The pump expands on the chamber 11 side, contracts on the discharge chamber 12 side after passing through the first seal land portion 15, and changes its volume to perform a pump action.

  Then, when the pump discharge pressure before the pump start or immediately after the start is zero or extremely low, the adjustment ring 7 has the plunger 25 abutted against the contact portion by the spring force of the spring member 27 of the adjustment mechanism 8 as shown in FIG. Since 23 is pressed and urged, it is urged to rotate clockwise. In this state, the restricting protrusion 22 abuts against the stopper surface 17 to restrict further clockwise rotation of the adjustment ring 7.

  In this state, the eccentric direction of the outer rotor 5 with respect to the inner rotor 4 via the adjustment ring 7 coincides with the first seal land portion 15 in the reference line J direction, so that from the suction chamber 11 side to the discharge chamber 11 side. The volume of the pump chamber 10a is maximum and passes through the first seal land portion 15, while the volume of the pump chamber 10b from the discharge chamber 12 side to the suction chamber 11 side is minimum and passes through the second seal land portion 16. Therefore, the pump discharge amount is maximized. For this reason, at the time of low pump rotation, the pump discharge pressure quickly rises as shown in FIG.

  Subsequently, when the pump discharge pressure increases as the pump rotation speed increases, the pump discharge pressure acts on the adjustment ring 7 from the discharge port 14 as described above, and the adjustment ring 7 is Rotating counterclockwise at an angle of, for example, about 15 ° against the spring force through the sliding contact portions 19 to 21 while leaving the stopper surface 17. The adjustment ring 7 stops rotating at a position where the pump discharge pressure and the spring force of the spring member 27 are balanced.

  As described above, the center point X of the inner peripheral surface 18a, that is, the center point E of the outer rotor 5 rotates about the center point O of the inner rotor 4 with respect to the rotation angle θ of the adjustment ring 7, In the state, the eccentric direction is 45 °. Therefore, the volume of the pump chamber 10 that passes through the first seal land portion 15 is slightly reduced, while the volume of the pump chamber 10 that passes through the second seal land portion 16 is slightly increased, so that the discharge chamber 12 from the suction chamber 11 side. The amount of oil flowing to the side decreases, that is, the pump discharge amount decreases, and the pump discharge pressure rises gently, as shown in FIG.

  Further, the adjustment ring 7 smoothly slides and rotates with respect to the curved surface portions 6a to 6c because the tip surfaces 19a to 21a of the sliding contact portions 19 to 21 are respectively formed in circular arc surfaces.

  Further, when the pump rotation speed increases, the pump discharge pressure acting on the adjustment ring 7 further increases, so that the adjustment ring 7 further resists the spring force of the spring member 27 as shown in FIG. Rotate clockwise to an angle of about 30 °. For this reason, the center point E of the outer rotor 5 has moved by approximately 90 °, and the eccentric direction with respect to the inner rotor 4 is approximately 90 ° angular position. For this reason, in the pump chamber 10, the volume when passing the seal land portion 15 from the suction chamber 11 to the discharge chamber 12 is substantially equal to the volume when passing the seal land portion 16 from the discharge chamber 12 to the suction chamber 11. The pump discharge amount is minimized.

  In this way, by rotating the adjustment ring 7 with the pump discharge pressure, the eccentric direction of the inner rotor 4 and the outer rotor 5 can be made variable with respect to the pump casing 1, thereby making the pump discharge amount variable and unnecessary fluid work. Can be reduced. As a result, power loss can be reduced.

  And according to the present Example, it is not necessary to form a gear part in the internal peripheral surface of the accommodation recessed part 6, and the outer peripheral surface of the adjustment ring 7, Three curved-surface site | parts 6a which consist of a trochoid curve in the internal peripheral surface of the accommodation recessed part 6 On the other hand, only the three sliding contact portions 19 to 21 corresponding to the outer periphery of the adjustment ring 7 are provided, so that these processes become easy and the cost can be reduced.

  Further, the adjustment ring 7 is not rotated and moved by meshing of the gear portion as in the prior art, but the front end surfaces 19a to 21a of the sliding contact portions 19 to 21 are connected to the curved surface portions 6a to 6c through a minute clearance. As shown in FIG. 12, the adjustment ring 7 rotates at a constant speed with respect to the increase in hydraulic pressure, and the occurrence of fluctuations in hydraulic pressure accompanying the increase in pump rotation is sufficiently suppressed, as shown in FIG. can do.

  Furthermore, since the adjustment ring 7 rotates against the spring force of the spring member 27 of the adjustment mechanism 8 according to the pump discharge pressure, the pump capacity is reduced when the predetermined discharge pressure is exceeded, and the hydraulic pressure is increased unnecessarily. It is possible to sufficiently suppress the increase in friction.

  Since the three sliding contact portions 19 to 21 are provided at intervals of approximately 120 ° in the circumferential direction of the adjustment ring 7, the adjustment ring 7 has three curved surface portions 6 a to 6 c of the pump casing 1 at three points. Since the rotational movement is performed while being in sliding contact, a stable rotational movement can be obtained.

  Moreover, since the pressure receiving areas of the first slidable contact part 19 and the third slidable contact part 12 in the rotation direction of the adjustment ring 7 are made different, the pump discharge pressure is efficiently converted to the rotational force of the adjustment ring 7 by a free magnification. Can be converted. Thereby, the spring set pressure of the spring member 27 of the adjustment mechanism 8 can be set freely.

  The present invention is not limited to the configuration of the above-described embodiment. For example, a low friction material may be formed on the surface of each curved surface portion 6a to 6c or the tip surface 19a to 21a of each sliding contact portion 19 to 21. This makes it possible to obtain a smoother rotation of the adjusting ring 7 while improving the sealing performance. It is also possible to apply to hydraulic equipment other than the internal combustion engine.

It is a front view of the state which removed the cover which shows embodiment of the variable displacement pump which concerns on this invention. It is an exploded perspective view of a variable displacement pump. It is a perspective view which shows the pump casing provided for a present Example. It is a front view of the adjustment ring provided for a present Example. It is procedure explanatory drawing which forms each curved surface part of the accommodation recessed part in a present Example. It is procedure explanatory drawing which similarly forms each curved-surface site | part. It is a figure explaining the pressure effect | action of the pump discharge pressure which acts on an adjustment ring. It is explanatory drawing of an effect | action of the pump discharge pressure which similarly acts on an adjustment ring. It is operation | movement explanatory drawing of the adjustment ring at the time of a pump stop or low rotation. It is operation | movement explanatory drawing of the adjustment ring at the time of pump rotation. It is operation | movement explanatory drawing of the adjustment ring at the time of pump high rotation. It is a characteristic view which shows the relationship between the pump rotation speed and pump discharge pressure of the variable displacement pump of a present Example. It is a characteristic view which shows the relationship between the pump rotation speed and pump discharge pressure in the conventional variable displacement pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pump casing 3 ... Drive shaft 4 ... Inner rotor 5 ... Outer rotor 4a ... Inner tooth 5a ... Outer tooth 6 ... Accommodating recessed part 6a-6c ... Curved surface part 7 ... Adjustment ring 8 ... Adjustment mechanism 10 ... Pump chamber 11 ... Suction chamber 12 ... Discharge chamber 13 ... Suction port 14 ... Discharge port 17 ... Stopper surface 19-21 ... Sliding contact part 19a-21a ... Tip surface 22 ... Regulating protrusion

Claims (4)

A pump casing having a suction port and a discharge port and having a housing recess formed therein;
An inner rotor and an outer rotor which are rotatably accommodated in the accommodating recess, and rotate while meshing with each other's inner and outer teeth;
A drive shaft fixed to the center of the inner rotor and applying a rotational force to the inner rotor;
An adjustment ring that is accommodated in the accommodation recess so as to be eccentrically rotatable, and that rotatably supports the outer circumferential surface of the outer rotor on the inner circumferential surface of the ring,
A variable displacement pump that obtains rotation of the adjusting ring and rotationally moves the outer rotor in the eccentric direction of the inner rotor to vary the pump discharge amount,
Set a radius R of an arbitrary length from the center of the inner rotor,
Draw a base circle of radius 2R / 3 for this radius R, set a rolling circle of radius R / 3 that rolls on this base circle,
A line connecting the center of the base circle and the center of the rolling circle as a reference line,
On the extension line of the reference line, set a fixed point for the distance of the eccentric amount in the radial direction of the inner rotor and the outer rotor from the center of the rolling circle to the opposite direction to the center of the base circle,
A trochoid curve represented by the locus of the fixed point when the rolling circle is rolled on the base circle is created, and a radius r of an arbitrary length is placed outside the normal line from the point on the trochoidal curve. A trochoidal curve represented by the locus of points that are
Formed in a predetermined position on the inner peripheral surface of the housing recess,
A plurality of sliding contact portions that slide in contact with the curved surface portion formed by the trochoidal curve of the inner circumferential surface of the accommodating recess are provided on the outer peripheral portion of the adjustment ring, and project radially outward.
Each of the sliding contact portions is formed in an arc shape of substantially the radius r centered on the position of the radius R from the center of the inner peripheral surface of the ring,
A variable displacement pump characterized in that the front end surface of each sliding contact portion is formed so as to be capable of sliding contact with the curved surface portion of the housing recess. The variable displacement pump according to claim 1, wherein three of the sliding contact portions are provided at approximately 120 ° intervals in the circumferential direction of the adjustment ring. The adjusting ring is urged to a position where one of the sliding contact portions is on the reference line by the pressing mechanism, and the pressing mechanism presses the adjusting mechanism as the discharge pressure of the pump increases. 3. The variable displacement pump according to claim 1, wherein the sliding contact portion rotates against the pressure while sliding on the inner peripheral surface of the housing recess. The variable capacity type according to any one of claims 1 to 3, wherein a pressure receiving area for receiving the pump discharge pressure of the at least one sliding contact portion is formed in a size different from other sliding contact portions. pump.

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