PUMP

FIELD OF THE INVENTION

The present invention relates to an improvement in a rotary displacement pump, viz., so-called, a pendulum slider pump, including an inner rotor, which is connected to an outer rotor via a plurality of pendulums (or called linkage plates), the outer rotor and the inner rotor being integrally rotated with the pendulums in a mutually eccentric relationship therebetween and the plurality of pendulums partitioning a space formed between the outer rotor and the inner rotor into a plurality of chambers.

BACKGROUND OF THE INVENTION

Each of a Japanese Patent No. 4909078 issued on Jan. 20, 2012 and a Japanese Patent Application Publication No. 2015-117695 published on Jun. 25, 2015 exemplifies a previously proposed rotary displacement pump called a pendulum slider pump. Such a pendulum slider pump as described above includes an inner rotor which is integrally rotated with a drive shaft and an outer rotor which is rotated within a cam ring in association with the rotation of the inner rotor. In addition, a plurality of pendulums (linkage plates) are disposed between the outer rotor and the inner rotor in order to transmit a rotational force from the inner rotor at an inner peripheral side to the outer rotor at an outer peripheral side. In details, each of the pendulums (linkage plates) includes: a head section at one end fitted slidably into a plate retaining groove which corresponds to an inner peripheral surface of the outer rotor; and a body section of a substantially triangular shape fitted slidably into a corresponding one of slots radially formed on the inner rotor. These plurality of pendulums link the outer rotor and the inner rotor and partition a space defined by the outer rotor and the inner rotor into a plurality of chambers. The outer rotor is located eccentrically with respect to the inner rotor. Hence, the pendulum slider pump described above obtains a pump action similar to a vane pump.

It should be noted that, as one aspect of this conventional pendulum slider pump, conversely, it is possible to structure the pendulum slider pump with the outer rotor as a drive side and the inner rotor as a driven side.

SUMMARY OF THE INVENTION

In each of the previously proposed pendulum slider pumps described above, basically, a transmission of a rotational torque is carried out through one of the plurality of pendulums. For example, in a case where the inner rotor is a drive side, one of the plurality of pendulums located at a discharge stroke side (namely, a side at which a volume of the chambers is decreased in association with the rotation) serves to perform the torque transmission, at least, during an angle into which 360° is equally divided. Since, during this torque transmission interval, a distance between the outer rotor and the inner rotor which are mutually in the eccentric relationship becomes gradually small, a corresponding one of the pendulums is moved backwardly into the corresponding one of the slots while varying the angle with respect to the corresponding one of the slots, acting as a kind of lever transmitting a force received from the head section to the outer rotor.

In such an operating principle as described above, during the torque transmission interval of the corresponding one of the pendulums, a rotational angle difference between the inner rotor and the outer rotor occurs. For example, in a pendulum slider pump with the inner rotor as the drive side, an angular velocity of the outer rotor is varied in an increase direction and in a decrease direction while the inner rotor makes one rotation at a constant angular velocity. Specifically, a variation of the angular velocity in the increase and the decrease directions occurs by a number of times equal to the number of the pendulums.

Consequently, a ripple occurs in a discharged fluid. In the same way, a load acted upon a driving source is periodically varied. In this respect, an unfavorable situation occurs. The previously proposed pendulum slider pump described in the Japanese Patent No. 4909078 lists up the reduction of the ripple in the discharged fluid as one of the tasks to be solved. However, this Japanese Patent does not disclose a specific means for making the angular velocity of the outer rotor which serves as the driven side constant.

Even in the other pendulum slider pump in which the outer rotor is the drive side, the variation of an angular velocity of the inner rotor which serves as the driven side in the increase and the decrease directions occurs similarly.

It is an object of the present invention to provide an improved pump which is capable of suppressing the ripple of discharged fluid and the periodical load variation acted upon the driving source by rotating the inner rotor and the outer rotor at mutually equal angular speeds.

According to one aspect of the present invention, there is provided a pump comprising: a cylindrical outer rotor having an inner peripheral surface on which a plurality of pendulum retaining grooves are formed, each pendulum retaining groove being of a letter C shape in cross section and being extended in an axial direction of the pump; an inner rotor disposed at an inner peripheral side of the outer rotor eccentrically to the outer rotor and having a plurality of slots formed on an outer peripheral surface of the inner rotor in a radial direction of the pump; and a plurality of pendulums, each pendulum having: a head section of a substantially circular shape in cross section slidably fitted into a corresponding one of the pendulum retaining grooves; and a body section of a substantially triangular shape in cross section connected to the head section via a neck section and slidably fitted into a corresponding one of the slots while contacting on side surfaces of both sides of the corresponding one of the slots and partitioning a space between the outer rotor and the inner rotor into a plurality of chambers, either of the outer rotor or the inner rotor being rotationally driven, wherein each of the pendulums has a torque transmission surface formed on one side surface of the body section opposed against a torque-transmission-side side surface of a corresponding one of the slots, the torque transmission surface having a profile such that a straight line section and a curved section extended from one end of an outer peripheral side of the straight line section to a side portion of the neck section are continued, the straight line section has a profile such that the straight line section makes a surface contact on the torque-transmission-side side surface of the corresponding one of the slots, at a reference angle position at which a perpendicular line orthogonal to an eccentric direction of the inner rotor and passing through a center of the inner rotor and the torque-transmission-side side surface of the corresponding one of the slots are made parallel to each other, and the curved section has a profile such that, at least, during a predetermined torque transmission angle including an angle into which 360° is equally divided by the number of pendulums, the curved section continues the contact on an opening edge of the torque-transmission-side side surface of the corresponding one of the slots and maintains rotational angles of both of the rotors mutually equally.

In a specific one aspect of the present invention, the inner rotor is rotationally driven, the outer rotor is driven, and the curved section is extended from the straight line section toward a reverse direction to (or a rear side of) a rotation direction of the inner rotor and the reference angle position is a point at which the torque transmission is started.

That is, at the reference angle position at which one of side surfaces of a corresponding one of the slots corresponding to a certain single pendulum parallel to the above-described perpendicular line, the straight line section of the torque transmission surface of the body section of the corresponding one of the pendulums is surface contacted on one of the side surfaces of the corresponding one of the slots at the torque transmission side and the torque transmission with the corresponding one of the pendulums as a kind of lever is started. A contact point between the torque transmission surface of the body section and one of the side surfaces which is an opposite side of the corresponding one of the slots is “a point of application of a force”, a contact point between the other side surface of the body section and the other side surface of the corresponding one of the slots is “a fulcrum”, and a contact point between the head section and the pendulum retaining groove is “a point of action”. Since the point of application of force is located at an outer peripheral end of the contact surface in a state in which the surface contact is made at the reference angle position, the point of application of force is located at the outer peripheral side with respect to the fulcrum and accordingly the torque transmission to the outer rotor is carried out and in association with the action of lever.

Since, at an angle position before the reference angle position, an end section (a terminal) at the inner peripheral side of the body section is contacted on the side surface at the torque transmission side of the corresponding one of the slots, the point of application of force is located at the inner peripheral side and, hence, the torque cannot be transmitted under this situation.

Then, when the inner rotor is rotated starting from the reference angle position, the curved section of the torque transmission surface is contacted on the opening edge at the torque transmission side of the corresponding one of the slots and the rotational torque transmission is carried out with this contact point as the point of application of force. Thereafter, this contact point gradually moved toward the outer peripheral side of the curved section (in other words, the tip side). In other words, while the contact point at the curved section is gradually moved toward the outer peripheral side, the transmission of the rotational torque is continued. At this time, the rotational angle of the outer rotor when the inner rotor which is the drive side is rotated in a unit angle is determined according to a profile (contour shape) of the curved section. Therefore, according to a setting of a profile of the curved section, the rotational angle of the inner rotor and the rotational angle of the outer rotor can mutually equally be maintained.

In addition, a profile of the curved section is set in such a way that, at least, the curved section continues the opening edge at the torque transmission side of the corresponding one of the slots during a predetermined torque transmission angle including an angle equally dividing 360° by the number of pendulums. Thus, by the plurality of pendulums, the torque transmission over 360° is continuously carried out.

In a case where the torque transmission angle is set exceeding the angle equally dividing 360° by the numbers of pendulums, a subsequent one of the pendulums reaches the reference angle position and the torque transmission is started before the end of the torque transmission through a preceding one of the pendulums. Hence, during a portion of the angle interval, two of the plurality of pendulums contribute simultaneously on the torque transmission.

In another specific aspect of the present invention, the outer rotor is rotationally driven, the inner rotor is driven, and the curved section is extended from the straight line section toward a reverse direction to (a rear side of) the rotation direction of the inner rotor, and the reference angle position is a point at which the torque transmission is ended.

In this case, the basic structure of the profile of the torque transmission remains the same as described above. However, the torque transmission start point and the torque transmission end point are reversed to the above-described points.

That is, at an angle position which is front side with respect to the rotation direction by a predetermined torque transmission angle from the above-described reference angle position, the curved section (particularly, a portion of the outer peripheral side thereof) of a corresponding one of the pendulums is contacted with the opening edge of the corresponding one of the slots and the transmission of the rotation torque is started. A contact point at the curved section is gradually moved toward the inner peripheral side. Then, when the contact point reaches the reference angle position, the straight line section of the torque transmission surface makes the surface contact with the side surface at the torque transmission side of the corresponding one of the slots and the torque transmission side of the corresponding one of the slots and the torque transmission is ended. During this time interval, it is possible to mutually maintain equally with each other between the rotation angle of the inner rotor and the rotation angle of the outer rotor by setting the profile of the curved section.

In another preferable aspect of the present invention, the curved section is projected from a virtual plane connecting an outer peripheral surface and a terminal outer surface of the body section located at an inner peripheral side of the corresponding one of the slots.

That is, when, during a required torque transmission angle from the reference angle position, the profile of the curved section is set in order for the two rotors to be interlocked with each other at equal angular speeds, the curved section is unnecessarily extended relatively largely toward the side section of each pendulum. Hence, as compared with each of the shapes of well known pendulums, a unique shape is resulted. In many cases, the curved section is projected and extended from the virtual plane.

In addition, from the similar reason, in another preferable aspect of the present invention, the curved section is constituted by a projection section projected in the side portion from a connecting section between the body section and the neck section and a recessed section is disposed at a position of an inner peripheral surface of the outer rotor adjacent to each of the pendulum retaining grooves to avoid an interference of the outer rotor against the projection section.

Furthermore, in a still another preferable aspect of the present invention, the opening edge of each of the slots at the torque transmission side of each of the slots which is contacted on the curved section of the corresponding one of the pendulums is rounded. Thus, a local wear at the contact point can be suppressed.

According to the present invention, in the, so-called, pendulum slider pump, the inner rotor and the outer rotor can be rotated at equal angular speeds. Thus, the ripple of discharged fluid and the periodical load variation acted upon the drive source can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view representing a state in which a cover is removed from a pump in a first preferred embodiment according to the present invention.

FIG. 2 is a plan view representing an essential part of the pump shown in FIG. 1.

FIG. 3 is an enlarged explanatory view of one of a plurality of slots and a corresponding one of a plurality of pendulums located at a reference angle position.

FIG. 4 is a plan view of the pump in a second preferred embodiment in which a torque transmission angle θ is largely set.

FIG. 5 is a plan view representing a third preferred embodiment of the pump in which the outer rotor is a drive side.

FIG. 6 is a plan view representing an essential part of a comparable example of the pump.

FIG. 7 is an enlarged explanatory view representing the plurality of pendulums at the torque transmission start point in the comparable example shown in FIG. 6.

FIG. 8 is an enlarged explanatory view representing the plurality of pendulums at a reference angle position in the comparable example shown in FIG. 6.

FIG. 9 is an enlarged explanatory view representing one of the plurality of pendulums at a torque transmission end point in the comparable example shown in FIG. 6.

FIG. 10 is a characteristic diagram representing a rotational angle difference of an inner rotor and an outer rotor in the compatible example shown in FIG. 6.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

First, a basic structure of a pendulum slider (type) pump according to the present invention will herein be explained.

FIG. 1 shows a first preferred embodiment of a pendulum slider (type) pump used as, for example, a hydraulic pressure pump of an internal combustion engine or a hydraulic pressure pump of an automatic transmission. The pump shown in FIG. 1 mainly includes: a hollow housing 1; an annular shaped cam ring 2 housed in housing 1; a cylindrically shaped outer rotor 3 arranged on an inner peripheral side of this cam ring 2; an inner rotor 4 arranged at a position of an inner peripheral side eccentric to outer rotor 3; a plurality of (for example, six) linkage plates (hereinafter, called pendulums) linking between outer rotor 3 and inner rotor 4; and a drive shaft 6 penetrated through housing 1 and linked to inner rotor 4.

The above-described housing 1 is divided into: a main frame (body) 11 formed by a cam ring housing chamber 13 as a recessed section; and a cover (not shown) enclosing an opening surface of cam ring housing chamber 13 in combination with this main body 11 as a lid. These main body (frame) 11 and cover are tightened together through bolts (not shown). Suction port 16 and discharge port 17 are respectively formed in crescent shapes.

Cam ring 2 is swingably supported within cam ring housing chamber 13 via a pin 14 attached onto one end of cam ring 2. Cam ring 2 is biased toward one of swing directions of cam ring 2 by means of a coil spring 15 attached onto the other end of cam ring 2.

A control hydraulic pressure chamber 18 is defined to oppose against a biasing force of coil spring 15 between the inner peripheral surface of cam ring housing chamber 13 and the outer peripheral surface of cam ring 2. A balance of the biasing forces of coil spring 15 and control hydraulic pressure chamber 18 determines a swing position of cam spring 2 and, thus, a pump capacity. It should be noted that, since this variable capacity mechanism is not an essential part of the present invention, the detailed explanation will herein be omitted.

Outer rotor 3 is formed cylindrically and its outer peripheral surface 3a is rotatably fitted into a cylindrical supporting surface 19 of cam ring 2. A plurality of pendulum (or plate) retaining grooves 21 each having a circular in cross section or a letter C shape in cross section are formed on an inner peripheral surface 3b of outer rotor 3 at a plurality of locations, for example, six locations of outer rotor 3. Each plate (pendulum) retaining groove 21 is extended in the axial direction of outer rotor 3 and both sides thereof are opened to end surfaces of outer rotor 3, respectively.

Inner rotor 4 arranged at the inner peripheral side of outer rotor 3 is positioned eccentrically with respect to a center of outer rotor 3 so that inner rotor 4 approaches inner peripheral surface 3b of outer rotor 3 and attached onto a drive shaft 6 so as to be rotated integrally with drive shaft 6.

In details, in the above-described first embodiment, since inner rotor 4 is the drive side and is mechanically driven according to an engine output and so on of the internal combustion engine. It should be noted that, since a relative eccentricity (quantity) between inner rotor 4 and outer rotor 3 is varied in accordance with the swing position of cam ring 2.

FIG. 1 shows a state in which the eccentricity (quantity) is a maximum.

Six rectangular slots 22 are radially formed on an outer peripheral surface 4a of inner rotor 4 at equal intervals of distance, the number of slots 22 corresponding to that of plate (pendulum) retaining grooves 21. In details, each of slots 22 has mutually parallel pairs of side surfaces 22a, 22b and these pairs of side surfaces 22a, 22b are formed along radius lines of inner rotor 4 so as to parallel to radius lines of inner rotor 4. Each slot 22 is extended in an axial direction of inner rotor 4, both ends of each slot 22 opened to an end surface of inner rotor 4, and both ends of each slot 22 are opened to end surfaces of inner rotor 4.

As described above, as a result such that inner rotor 4 is eccentric to inner peripheral surface 3b of outer rotor 3, a space in a crescent shape is formed between inner rotor 4 and outer rotor 3. Then, this crescent shaped space is furthermore partitioned into six chambers 24 with six pendulums 5. Each of above-described pendulums 5 is formed in a plate like shape having a pendulum shaped cross section approximated to a substantially triangular shape, supported swingably on each of plate retaining grooves 21.

As easily appreciated from FIG. 1, a distance between inner peripheral surface 3b of outer rotor 3 and outer peripheral surface 4a of inner rotor 4 is varied in accordance with a rotational position of mutually eccentric outer rotor 3 and inner rotor 4 so that a volume of each chamber 24 partitioned by means of linkage plates (pendulums 5) is varied in an increase direction or in a decrease direction. Hence, by a rotation of outer rotor 3 and inner rotor 4 in a counterclockwise direction of FIG. 1, a pump action by which oil is supplied to discharge port 17 from suction port 16 under pressure can be obtained.

FIG. 2 shows a detailed explanatory view of the pump in the first embodiment shown in FIG. 1. Outer rotor 3, inner rotor 4, and pendulums 5 which are main components of the pump. Each of pendulums 5 includes: a head section 31 of a substantially circular shape in cross section swingably fitted into a corresponding one of plate (pendulum) retaining grooves 21 of outer rotor 3; a body section 32 of the substantially triangular shape in cross section fitted slidably into a corresponding one of slots 22 of inner rotor 4; and a neck section 33 connecting head section 31 and body section 32. Neck section 33 has a thickness smaller than a diameter of head section 31 (a size along a peripheral direction of each rotor 3, 4) and body section 32 has a substantially triangular cross sectional shape approximated to an isosceles triangular shape in which a thickness of body section 32 is gradually expanded toward a terminal section 32a of the inner peripheral side thereof from this neck section 33. Forward and rearward (a front side or a forward side to a rotation direction ω and a rear side or a backward side to the rotation direction) corner sections 32b, 32c are formed on respective curved surfaces so that these corner sections 32b, 32c are substantially contacted on side surfaces 22a, 22b at both sides of the corresponding one of slots 22 even if corresponding one of pendulums 5 is swung within the corresponding one of pendulums 5. Thus, it is possible for each pendulum 5 to swing and move along the radius direction of inner rotor 4 with the corresponding one of slots 22 while contacting on side surfaces 22a, 22b of both sides of the corresponding one of slots 22.

It should herein be noted that, in FIG. 2, inner rotor 4 is rotated in a counterclockwise direction as the drive side (a direction denoted by an arrow mark co in FIG. 2) and outer rotor 3 is driven in the same direction via pendulums 5. Hence, one of side surfaces 22b which is relatively rear side (backward side) with respect to rotation direction w in two side surfaces 22a, 22b provides a side surface (this is called a torque-transmission-side side surface 22b) for the torque transmission. In each of pendulums 5, one of surfaces of each pendulum 5 which is opposed against torque-transmission-side side surface 22b of a corresponding one of slots 22 provides a torque transmission surface 35.

Hence, torque-transmission-side side surface 22b of each of slots 22 which is the drive side pushes torque transmission surface 35 along rotation direction ω and this force is transmitted to outer rotor 3 via head section 31. Thus, outer rotor 3 is driven.

Such a transmission of the rotational torque as described above is basically carried out by a certain single pendulum 5 placed at a particular angle position from among six pendulums 5.

In the structure of the pump in which inner rotor 4 is the drive side, the certain single pendulum 5 placed at a discharge stroke side (namely, a side at which the volume of each of chambers 24 is decreased in association with the rotation) assumes the torque transmission. In the first embodiment shown in FIG. 2, while one of pendulums 5 to which a reference numeral of 5A is attached is rotated until a reach to a position of one of the remaining pendulums 5 to which a reference numeral of 5B is attached, the corresponding pendulum 5A carries out the transmission of the rotational torque. In other words, a line M in FIG. 2 denotes an angle position at which a torque transmission start point is defined. In the embodiment of FIG. 2, line M denotes the angle position which is the start point of the torque transmission by means of single one of pendulums 5 and a line N denotes the angle position by means of the single one of pendulums 5 which is the end point of the torque transmission.

It should herein be noted that straight line L denotes an eccentric direction of a center of inner rotor 4 with respect to a center of outer rotor 3 and line M which provides the torque transmission line is a perpendicular line orthogonal to eccentric direction L of inner rotor 4 passing through the center of inner rotor 4. When the angle position of inner rotor 4 which provides this perpendicular line M to be parallel to torque-transmission-side side surface 22b of the corresponding slot 22 is defined as “a reference angule position”. When inner rotor 4 reaches this reference angle position with respect to certain single slot 22, the torque transmission through certain single pendulum 5 in the corresponding one of slots 22 is started. Then, in this embodiment, torque transmission angle θ is set to 60° which is an angle into which 360° is equally divided by the number of pendulums 5 (six).

Then, when inner rotor 4 reaches this reference angle position, the torque transmission is started by certain single pendulums 5 at the corresponding one of slots 22. While inner rotor is rotated by 60° from the reference angle position, the torque transmission through the corresponding one of pendulums 5 is carried out. When one of pendulums 5 whose reference numerals 5A is rotated through 60°, the torque transmission is ended. When the torque transmission through the subsequent one of pendulums 5 whose reference numeral is attached as 5C reaches torque transmission start point M (in other words, the reference angle position), this subsequent one of pendulums 5 (5C) continuously carries out the torque transmission. Thus, while inner rotor 4 and outer rotor 3 make one rotation, the torque transmission is continued without interruption. It should be noted that above-described torque transmission start point M and torque transmission end point N are determined by a profile of torque transmission surface 35 as will be described later.

Next, the profile of torque transmission surface 35 required to make the angular velocity of outer rotor 3 constant will furthermore be explained in more details.

FIG. 3 shows the corresponding one of slots 22 of inner rotor 4 and the corresponding one of pendulums 5 located at the reference angle position in an enlargement view. As shown in FIG. 3, torque transmission surface 35 of each of pendulums 5 has a profile such that a straight line section 35a having a straight line slanted to form one side of a triangle and a curved section 35b extended toward a side of neck section 33 (in other words, a rear (backward) side in rotation direction co) from one end of straight line section 35a at the outer peripheral side thereof are continued. Curved section 35b is constituted as a projection section 36 which is projected from a connecting section between body section 32 and neck section 33 toward the side direction.

In more details, the profile of straight line section 35a is defined such that straight line section 35a makes a surface contact with torque-transmission-side side surface 22b of the corresponding one of slots 22 when inner rotor 4 is placed at the reference angle position as shown in FIG. 3. In addition, when inner rotor 4 is furthermore rotated from the reference angle position, the curved section 35b has a profile such that curved section 35b continues to be contacted on an opening edge 22c of the corresponding one of slots 22 at the torque transmission side of the corresponding one of slots 22 and the rotation angles of inner rotor 4 and outer rotor 3 are maintained in a mutually equal angular relationship. In order to obtain such a relationship between both rotors 3 and 4 as described above, curved section 35b is smoothly continued on one end of straight line section 35a and a curvature of curved section 35b is gradually increased from this straight line section 35a toward a tip of the outer peripheral side of curved section 35b.

It should be noted that, in the embodiment shown in FIG. 3, opening edge 22c of each of slots 22 is rounded with a radius of curvature smaller than the radius of curvature of curved section 35b so that the contact with curved section 35b provides at least partially a rolling contact.

In the structure described above, while the rotation torque is transmitted from inner rotor 4 to outer rotor 3 via each of pendulums 5, a difference between rotation angles of inner rotor 4 and outer rotor 3 gives zero.

That is, as shown in FIG. 3, one of linkage plates (pendulums) 5 during the transmission of rotation torque functions as a kind of lever in which a contact point P1 between torque transmission surface 35 of body section 32 and torque-transmission-surface-side side surface 22b of the corresponding one of slots 22 is “a point of a lever to which force is applied”, a contact point P2 between a surface opposite to body section 32 (a corner section 32b in a posture of FIG. 3) and a side surface 22a opposite to the corresponding one of slots 22 in a “fulcrum”, and a contact point P3 between head section 31 and a corresponding one of plate (pendulum) retaining grooves 21 is “an application point”, and a force applied from torque-transmission-side side surface 22b of the corresponding one of slots 22 to the point of application of force P1 is transmitted to outer rotor 3.

In a state where straight line section 35a of torque transmission surface 35 makes the surface contact on torque-transmission-side side surface 22b when inner rotor 4 is placed at the reference angle position, point of application of force P1 is located on a most outer peripheral side of straight line section 35a. Hence, as a radial directional position from a center of inner rotor 4, force point P1 is located toward an outer peripheral side with respect to fulcrum P2 so that the torque transmission to outer rotor 3 in association with the lever action is carried out.

Whereas, at an angle position which is present before the forward (front) side than the reference angle position, for example, as shown in FIG. 2 by one of pendulums 5 to which reference numeral of 5C is attached, corner section 32c of body section 32 is contacted on torque-transmission-side side surface 22b of the corresponding one of slots 22. Thus, since point of force of P1 becomes a positional relationship in which point of force P1 is located at more inner peripheral side with respect to point of fulcrum P2, no rotational torque can be transmitted to action point P3. Hence, it is not until inner rotor 4 is rotated and reaches the reference angle position that the torque transmission is started.

Then, as inner rotor 4 is further rotated from the reference angle position, curved section 35b of torque transmission surface 35 is contacted on opening edge 22c of the torque transmission side of the corresponding one of slots 22 and the rotational torque transmission with contact point P1 as “force application point”. Then, this contact point P1 is gradually moved toward the outer peripheral side (in other words, toward the tip side) of curved section 35b. In other words, while contact point P1 is gradually moved toward the outer peripheral side of curved section 35b, the transmission of the rotational torque is continued. At this time, the rotational angle of outer rotor 3 when inner rotor 4 which is the drive side is rotated through a unit angle is determined according to the profile of curved section 35b. Hence, the profile of curved section 35b is set so that the rotational angle of inner rotor 4 and the rotational angle of outer rotor 3 are mutually equally maintained and the rotational angular difference of both inner and outer rotors 4 and 3 can be maintained at zero.

A specific profile of curved section 35b can be determined by plotting continuously contact point P1 required when, for example, each of inner rotor 4 and outer rotor 3 is rotated by an equal unit angle.

In this way, curved section 35b required to zero the rotational angular difference between inner rotor 4 and outer rotor 3 during torque transmission angle θ is relatively long and is projected largely toward the rear side (a reverse direction side) to rotational direction ω. In the first embodiment, curved section 35b is constituted by a projection section 36 which is projected far away from neck section 33. Hence, in the embodiment shown in FIG. 3, when a virtual plane PL connecting outer peripheral surface of head section 31 and corner section 32c of body section 32 is supposed (to be present), curved section 35b (projection section 36) is extended externally from this virtual plane PL. This shape is a peculiar (unique) shape as compared to any of well known pendulums 5.

It should also be noted that a recessed section 37 is formed on the inner peripheral surface 3b of outer rotor 3 which is adjacent to each of pendulum retaining grooves 21 in order to avoid an interference between projection section 36 and outer rotor 3 when the corresponding one of pendulums 5 is largely inclined.

It should also be noted that, in the embodiment shown in FIGS. 2 and 3, each slot 22 has a shape which is symmetric to the forward and backward directions with a radius line passing the center of inner rotor 4 as a center. In other words, the center of a groove width of each slot 22 is coincident with the radius line. However, according to the present invention, in the same way as a previously proposed pendulum slider (type) pump, each of slots 22 may slightly be offset to the forward and backward directions with respect to the radius line. However, side surfaces 22a, 22b of each slot 22 are required to be parallel to the radius line passing through the center of inner rotor 4. Even in the structure in which slots 22 are offset as described above, the reference angle position is determined in the similar manner.

Next, FIG. 4 shows a second preferred embodiment of the pendulum slider (type) pump in which torque transmission angle θ is larger than the angle (60°) into which 360° is equally divided by the number of pendulums 5. Specifically, in the first embodiment, the number of pendulums 5 are six and 360° is equally divided into 60°. However, torque transmission angle θ in the second embodiment is set to be 65° larger than 60° in the first embodiment. However, this can be achieved by setting the profile of curved section 35b larger than that of the first embodiment described above.

In such an arrangement described above, two pendulums 5 simultaneously carrying out the torque transmission at angular intervals of angles α and β which are initial and final angular stages of torque transmission angle θ. Hence, a load is dispersed into two pendulums 5 and when pendulums 5 carrying out the torque transmission are transited from one of slots 22 to the subsequent one of slots 22, this transition of two slots 22 becomes more smooth.

A comparative examples of the pendulum slider (type) pump will be explained by reference to FIGS. 6 through 10. In FIG. 6, straight line L denotes an eccentric direction of the center of inner rotor 4 with respect to the center of outer rotor 3 and line M denotes a perpendicular line orthogonal to eccentric direction L of inner rotor 4 passing through the center of inner rotor 4.

In the first and second embodiments according to the present invention, this perpendicular line M is coincident with the torque transmission line. However, in the comparative example, torque transmission angle θ from torque transmission start point m to perpendicular line M is present in both sides of perpendicular line M. In comparative example of FIG. 6, torque transmission angle θ is 60°. This torque transmission angle θ is divided into a first interval θ1 from torque transmission start point m to perpendicular line M and a second interval θ2 from perpendicular line M to torque transmission end point N.

Although each of pendulums 50 in the comparative example shown in FIG. 6 has a different profile from each end of pendulums 5 in the each of first and second embodiments, each of pendulums 50 includes torque transmission surface 350 having straight line section 350a and curved section 350b.

FIG. 7 shows a relationship in the comparative example between corresponding one of pendulums 50 and slots 220 at torque transmission start point m. As shown in FIG. 7, at this time point of FIG. 7, straight line section 350a makes the surface contact on torque-transmission-“side side surface 220b of the corresponding one of slots 220. The torque transmission is started according to the relationship among “the point of application of force”, “the fulcrum”, and “point of action”.

Next, FIG. 8 shows a state in which torque-transmission-side side surface 220b of slot 220 in the comparative example becomes parallel to perpendicular line M, namely, FIG. 8 shows a state in which inner rotor 4 has reached the reference angle position. It should be noted that straight line section 350a continues to make the surface contact on torque-transmission-side side surface 220b of the corresponding one of slots 220 up to this time at which inner rotor 4 reaches the reference angle position.

That is, during the transition of first interval θ1 from the state shown in FIG. 7 to the state shown in FIG. 8, the corresponding one of slots 220 is slid toward the inner peripheral side within each of slots 220. During this interval, an inclination angle of one of pendulums 50 with respect to the radius line of inner rotor 4 is constant. Hence, since an angular velocity of inner rotor 4 and the angular velocity of outer rotor 3 cannot be made equal to each other and the rotation angular difference is unavoidably generated. In details, the angular velocity of outer rotor 3 is relatively large during first interval θ1.

When inner rotor 4 exceeds the reference angle position, opening edge 220c of the corresponding one of slots 220 at the torque transmission side is contacted on curved section 350b of torque transmission surface 350 and the torque transmission is continued while moving on curved section 350b. In details, during second interval of θ2, the torque transmission is continued while the contact point moving on curved section 350b. That is, during second interval θ2, the torque transmission is carried out by curved section 350b. FIG. 9 shows the state of inner rotor 4 and outer rotor 3 when inner rotor 4 reaches torque transmission end point N, an end terminal of curved The end terminal at the outer peripheral side of curved section 350b is contacted on opening edge 220c of the corresponding one of slots 220. It should herein be noted that the angle position of inner rotor 4 shown in FIG. 9 provides the torque transmission end point N and, simultaneously, the torque transmission of the shown pendulum 50 at torque transmission start point m for the subsequent one of pendulums 50. The rotational angular difference of inner rotor 4 and outer rotor 3 which is zero at torque transmission start point m shown in FIG. 7 is required to return to zero again at torque transmission end point N shown in FIG. 9. Unavoidably, the profile of curved section 350b is set to such that the angular velocity becomes relatively small.

FIG. 10 shows a characteristic of the rotational angular difference between inner rotor 4 and outer rotor 3 in the comparative example shown in FIGS. 6 through 9. A lateral axis of this graph denotes an angle of inner rotor 4 and, in the shown comparative example in which inner rotor 4 is the drive side, rotation direction of ω is denoted by an arrow ω. A longitudinal axis of this graph denotes the rotational angle difference of two rotors 3 and 4. A lower side of this graph provides a lead side (advance) side of outer rotor 3.

As shown in FIG. 10, during first interval θ1 starting from transmission start point m, the angular velocity of outer rotor 3 being relatively larger and the rotation angular difference being abruptly expanded. When inner rotor 4 is placed at the reference angle position (the position corresponding to perpendicular line M), the rotational angular difference becomes a maximum. During second interval θ2, the angular velocity of outer rotor 3 becomes, reversely, small and, at the torque transmission end point N at which second interval of θ2 is ended, the rotational angular difference is again zeroed.

Hence, such an angular velocity variation of outer rotor 3 is generated for each pendulum 50 (for each of 60°) and a ripple of discharged fluid and a load variation in the drive source are introduced.

In order to prevent such a characteristic of the comparative example as described above, outer rotor 3 is rotated to follow up inner rotor 4 while maintaining the rotational angular difference between inner rotor 4 and outer rotor 3 at zero, in the above-described embodiments. Hence, the ripple of discharged fluid and the load variation in the drive source are suppressed.

It should be noted that the pump in the first embodiment shown in FIG. 1 is constituted as a variable capacity pump in which the eccentricity (quantity) between inner rotor 4 and outer rotor 3 is varied in accordance with the swing position of cam ring 2. In such a pump in which the eccentricity (quantity) as described above, the rotational angular velocity between inner rotor 4 and outer rotor 3 becomes zero at a time of a particular eccentricity (quantity). In the shown embodiments, the rotational angular difference is set to be zero. It is possible to set the rotational angular difference to be zero at a time of a particular intermediate eccentricity (quantity).

It is, of course, possible to apply the present invention to a pump of a fixed capacity in which the eccentricity (quantity) is fixed. In addition, the number of pendulums 5 is not limited to six as described in the first embodiment. The present invention is applicable to the pump having an arbitrary number of pendulums 5.

Furthermore, the present invention is applicable to the pendulum slider (type) pump in which the outer rotor is the drive side and the inner rotor is driven side.

FIG. 5 shows a third preferred embodiment of the pendulum slider (type) pump in which outer rotor 300 functions as a rotor of an electric (electrically driven) motor which is directly rotationally driven. Outer rotor 300 is rotatably supported in housing 100. A plurality of, for example, six permanent magnets 101 are buried at equal intervals into the outer peripheral section of outer rotor 300. An annular stator core 102 constituting the electric (electrically driven) motor together with outer rotor 300 includes a nine slot stator core 103 of laminated iron cores having a plurality of, for example, nine poles 103a and coils 104 wound on respective poles 103a.

It should be noted that outer rotor 300 is rotated in the counterclockwise direction shown by an arrow mark with ω. Accordingly, inner rotor 4 is driven and rotated in the same direction as outer rotor 300 to obtain the pump action. It should be noted that, since the torque is transmitted from torque transmission surface 35 of the corresponding one of pendulums 50 to torque-transmission-side side surface 22b of the corresponding one of slots 22 in the third embodiment of FIG. 5 in which outer rotor 300 is the drive side, directions of individual pendulums 5 are opposite to the rotational direction of ω.

In other words, the relationship between pendulums 5 and slots 22 in the case of pump shown in FIG. 5 is substantially equal to the structure in which outer rotor 3 (300) is, reversely, rotationally driven in the clockwise direction in FIGS. 2 and 3. Then, “transmission end point N” in FIG. 2 provides the “transmission start point” and “transmission end point M” in FIG. 2 provides the transmission end point. Hence, from a state in which a most outer peripheral section of curved section 35b of torque transmission surface 35 of the corresponding one of pendulums 5 is contacted on opening edge 22c at the torque transmission side of the corresponding one of pendulums 5, the torque transmission is started. In accordance with the profile of this curved section 35b, inner rotor 4 is driven while such a relationship that inner rotor 4 is rotated by an angle equal to the rotation of the unit rotational angle of outer rotor 3 (300) is maintained. Then, at a time point at which side surfaces 22a, 22b of the corresponding one of slots 22 make surface contact on torque-transmission-side side surface 22b of the corresponding one of slots 22, the torque transmission is ended. At a position at which outer rotor 3 (300) is rotated further than the reference angle position (refer to one of pendulums 5 to which reference numeral of 5C is attached), the torque transmission is not possible in the same way as described in the first embodiment.

Hence, even in the pump in the case of the third embodiment shown in FIG. 5, the rotational angular difference between outer rotor 300 and inner rotor 4 can be maintained at zero and the ripple of discharged fluid and the load variation as the electric (electrically driven motor) motor can be suppressed.

It should be noted that, although, in the third embodiment shown in FIG. 5, torque transmission angle θ gives 60° to which, for example, 360° is equally divided by the number of pendulums 5, it is possible to set a larger angle than 60° in the same way as the second embodiment. In this case, the pump is structured so that the torque transmission start point becomes earlier. That is, in the structure in which inner rotor 4 is driven as shown in FIG. 5, curved section 35b of torque transmission surface 35 is extended toward the forward side of rotational direction co from straight line section 35a and by more elongating this curved section 35b, the torque transmission start point can be made earlier so that torque transmission angle θ can widely be obtained. It should be noted that it is necessary that the torque transmission end point is always at the above-described reference angle position.

It should finally be noted that, in FIGS. 2, 4, 5, and 6, suction port 16 and discharge port 17 are omitted only for explanation convenience.

This application is based on a prior Japanese Patent Application No. 2016-240779 filed in Japan on Dec. 13, 2016. The entire contents of this Japanese Patent Application No. 2016-240779 are hereby incorporated by reference. Although the invention has been described above by reference to certain embodiments according to the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in the light of the above teachings. The scope of the invention is defined with reference to the following claims.

EXPLANATIONS OF SIGNS

- 1 . . . housing
- 2 . . . cam ring
- 3 . . . outer rotor
- 4 . . . inner rotor
- 5 . . . pendulums
- 21 . . . pendulum retaining grooves
- 22 . . . slots
- 22
  b . . . torque-transmission-side side surface
- 22
  c . . . opening edge
- 31 . . . head section
- 32 . . . body section
- 33 . . . neck section
- 35 . . . torque transmission surface
- 35
  a . . . straight line section
- 35
  b . . . curved section

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CPC

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Priority Claims (1)