JP3991755B2 - Vane pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vane pump, and is suitable, for example, as a hydraulic device for power steering of a vehicle.
[0002]
[Prior art]
4A and 4B show a schematic configuration of a conventional vane pump. FIG. 4A is a schematic configuration diagram of a side surface inside the vane pump, and FIG. 4B is an enlarged view of a portion of the vane.
[0003]
As shown in FIG. 4A, the conventional vane pump includes a cam ring 1 having an elliptical inner peripheral surface, a rotor 2 rotating in the cam ring 1, slits 3 provided radially in the rotor 2, The slit 3 is provided with a vane 4 that slides in contact with the inner peripheral surface of the cam ring 1. The space formed by the inner peripheral surface of the cam ring 1 and the outer peripheral surface of the rotor 2 has oil or the like. Two systems of suction ports 21 and discharge ports 22 for supplying and discharging the liquid are provided at positions symmetrical to the center of the rotor 2. Although not shown, the discharge port 22 communicates with the slit 3 and has a structure in which the discharge pressure of the liquid is used as the back pressure of the vane 4 in the slit 3.
[0004]
Since the cam ring 1 has an elliptical inner peripheral surface, the vane 4 reciprocates so as to expand and contract in the slit 3 as the rotor 2 rotates. That is, the centrifugal force caused by the rotation of the rotor 2 acts on the vane 4, and the back pressure caused by the discharge pressure acts on the inner end of the vane 4, so that the tip (outer end) of the vane 4 is always in contact with the inner peripheral surface of the cam ring 1. Thus, the vane 4 is pushed radially outward. Since the inner peripheral surface of the cam ring 1 has an elliptical shape, the tip of the vane 4 slides along the shape, and the vane 4 expands and contracts in the slit 3. Therefore, as the rotor 2 rotates, the inner peripheral surface of the cam ring 1, the outer peripheral surface of the rotor 2, and the gap portion 5 formed by the vanes 4 repeatedly increase and decrease in volume.
[0005]
Utilizing the above operation state, the liquid supplied to the suction port 21 is supplied to the gap portion 5 as the distance between the inner circumferential surface of the cam ring 1 and the outer circumferential surface of the rotor 2 increases (the volume of the gap portion 5 increases). As the distance between the inner peripheral surface of the cam ring 1 and the outer peripheral surface of the rotor 2 decreases (the volume of the gap 5 decreases), the liquid sucked into the gap 5 is compressed and discharged to the discharge port 22. Then, a liquid having an arbitrary pressure is supplied to the outside.
[0006]
The vane pump described above is used as a hydraulic device. Particularly, when used for power steering, if the inner peripheral surface of the cam ring 1 is a simple ellipse, pulsation occurs during the discharge of the compressed liquid, and the discharge efficiency is increased. There is a problem of losing. In addition, there is vibration and noise of the piping through which the compressed liquid passes and the equipment receiving the supply. For this reason, the inner peripheral surface of the cam ring is not made into a simple oval shape, but by providing uneven portions, concave portions or convex portions at appropriate positions, pulsation during discharge is suppressed, stable discharge pressure is maintained, and discharge efficiency is improved. It is improving. Note that the concave and convex portions include a change in radius such that the radius of the inner peripheral surface changes greatly.
[0007]
FIG. 4B is an enlarged view of the vane portion of the vane pump, and shows a state of the vane in contact with the cam ring having an uneven portion on the inner peripheral surface. For comparison with the concavo-convex portion, the elliptic curve of the original inner peripheral surface of the cam ring is indicated by a dotted line.
[0008]
As shown in FIG. 4 (b), the slit 3 provided in the rotor 2 allows a slight clearance (gap) between the vane 4 due to the expansion and contraction movement of the vane 4. Further, the tip of the vane 4 is formed in an arcuate curved surface so as to be in smooth contact with the inner peripheral surface of the cam ring 1. During rotation of the rotor 2, due to the sliding resistance between the inner peripheral surface of the cam ring 1 and the tip of the vane 4, a force acts on the tip of the vane 4 in the direction opposite to the rotation direction of the rotor 2 and is provided in the slit 3. It will tilt by the amount of clearance. That is, the center line 4a of the vane 4 during the rotation of the rotor 2 has an inclination δ with respect to the center line 3a of the slit 3, and the tangent to the inner peripheral surface of the cam ring 1 is not perpendicular but acute. It touches with an inclination. This inclination is unavoidable in terms of structure and cannot be made zero.
[0009]
[Problems to be solved by the invention]
When the curvature of the inner peripheral surface of the cam ring 1 is sufficiently large with respect to the curved surface at the tip of the vane 4, even when the vane 4 is inclined and contacts the inner peripheral surface of the cam ring 1 as described above, Is in contact with the inner peripheral surface of the cam ring 1, the tip of the vane 4 smoothly slides on the inner peripheral surface of the cam ring 1.
[0010]
However, particularly in a vane pump used for power steering or the like, a concave portion 1a and a convex portion 1b as shown in FIG. 4B are provided on the inner peripheral surface of the cam ring 1 in order to suppress pulsation during discharge and improve discharge efficiency. The curvature of the inner peripheral surface of the cam ring 1 is greatly changed, and a portion where the inner peripheral surface of the cam ring 1 is in contact with the vane 4 at an acute angle is generated. As described above, when the rotor 2 rotates, the vane 4 is inclined with respect to the slit 3 due to the sliding resistance with the cam ring 1 and the clearance in the slit 3. The inner peripheral surface of the cam ring 1 is further in contact with an acute angle. Further, the end portion of the curved surface at the tip of the vane 4 is not particularly chamfered and has a corner portion 4b.
[0011]
In this state, that is, when the vane 4 and the inner peripheral surface of the cam ring 1 are in contact with each other at an acute angle and the vane 4 has a corner 4b at the tip, the corner 4b at the tip of the vane 4 is cam ring due to the inclination of the vane 4. 1 is caught on the inner peripheral surface and cannot slide smoothly, but generates abnormal noise (metal friction noise) and slides. In addition, the curvature of the concave and convex portions on the inner peripheral surface of the cam ring 1 and the curvature of the curved surface of the tip of the vane 4 are caught in alignment and cannot be smoothly slid. May occur and slide. This phenomenon leads to wear of the inner peripheral surface of the cam ring 1 and the vane 4, which is not preferable in terms of durability of the vane pump, and may shorten the life of the vane pump.
[0012]
In a vane pump used for power steering of a vehicle, when the steering is operated at a low speed (particularly noticeable during steering steering), the above phenomenon is caused and abnormal noise is generated. The above phenomenon is considered to be related to the hydraulic pulsation, which is also a problem in terms of stability of the discharge pressure of the vane pump.
[0013]
In view of the above problems, the present invention provides a vane pump including a vane that is always in smooth contact with the inner peripheral surface of a cam ring.
[0014]
[Means for Solving the Problems]
A vane pump according to the present invention that solves the above-described problems is a vane pump that slides in contact with the inner peripheral surface of a cam ring that is disposed in a slit radially provided on a rotor and has at least one of irregularities that change in curvature. An arcuate convex portion that smoothly moves on the inner peripheral surface of the cam ring is formed on the rotation direction side of the rotor at the tip portion.
[0015]
A vane pump according to the present invention that solves the above-described problems is a vane pump that slides in contact with the inner peripheral surface of a cam ring that is disposed in a slit radially provided on a rotor and has at least one of irregularities that change in curvature. A curved surface having a radius of curvature sufficiently larger than the radius of curvature of the inner peripheral surface of the cam ring is formed on the tip portion on the rotational direction side of the rotor so as to smoothly move the inner peripheral surface of the cam ring.
[0017]
The vane pump according to the present invention for solving the above-described problems is characterized in that the slit includes a cutout portion formed in accordance with the shape of the convex portion, and the convex portion at the tip of the vane can be accommodated .
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The basic configuration of the vane pump according to the present invention is the same as that of the vane pump shown in FIGS. That is, the cam ring 1 having concave and convex portions 1a and 1b on the inner peripheral surface, the rotor 2 rotating in the cam ring 1, the slits 3 provided radially in the rotor 2, and the tip of the cam 3 Is provided with a vane 4 that slides in contact with the inner peripheral surface of the cam ring 1. However, the present invention is characterized by the shape of the vane, particularly the shape of the tip of the vane.
[0019]
Example 1
FIG. 1 is a schematic view of a vane shape of a vane pump showing an example of an embodiment according to the present invention.
In FIG. 1, the same reference numerals are given to the same components as those in the conventional technology, and duplicate descriptions are omitted. For comparison with the uneven portion, the elliptic curve of the inner peripheral surface of the original cam ring is indicated by a dotted line.
[0020]
As shown in FIG. 1, the vane 4 is formed by forming an arcuate convex portion 4 c on the rotation direction side of the rotor 2 at the tip of the vane 4. That is, even if the inner peripheral surface of the cam ring 1 has a portion that is in contact with the vane 4 at an acute angle, the tip of the vane 4 is always in contact with the inner peripheral surface of the cam ring 1 at a smooth curved surface portion. The part has an arcuate curved surface (convex part 4 c) protruding from the rotation direction side of the rotor 2. In other words, the portion of the tip of the vane 4 that contacts the inner peripheral surface of the cam ring 1 has a p shape (or q shape) when viewed from the side. The curvature of the curved surface of the arc-shaped convex portion 4 c is appropriately determined according to the curvature of the irregularities on the inner peripheral surface of the cam ring 1.
[0021]
In addition, a notch 3c that matches the shape of the convex portion 4c of the vane 4 is formed on the rotation direction side of the rotor 2 of the slit 3. That is, it is considered that when the vane 4 is pushed back into the slit 3, the convex portion 4c is properly accommodated so as not to impair the function of the vane pump. In addition, in FIG. 1, the state by which the vane 4 was pushed back was shown with the dashed-dotted line.
[0022]
Even if the vane 4 is inclined by the sliding resistance, and the inner peripheral surface of the cam ring 1 has irregularities and has a portion that is in contact with the vane 4 at an acute angle, the tip of the vane 4 has the above-described shape. That is, since there is no corner on the rotational direction side of the tip of the vane 4, the inner peripheral surface of the cam ring 1 and the tip of the vane 4 are always in smooth contact, and the vane 4 smoothly slides the inner peripheral surface of the cam ring 1. I can move. Therefore, it is possible to prevent abnormal noise due to catching between the inner peripheral surface of the cam ring 1 and the vane 4 and to prevent wear of the vane pump itself.
[0023]
Further, by having the above shape, the mass of the tip of the vane 4 is increased, and the centrifugal force to the vane 4 that works when the rotor 2 rotates is also increased, so that the pressing force to the inner peripheral surface of the cam ring 1 is increased. The airtightness between the cam ring 1 and the vane 4 is improved.
[0024]
(Example 2)
FIG. 2 is a schematic view of a vane shape of a vane pump showing another example of the embodiment according to the present invention.
In FIG. 2, the same number is given to the same component as the prior art, and the duplicate description is omitted. For comparison with the uneven portion, the elliptic curve of the inner peripheral surface of the original cam ring is indicated by a dotted line.
[0025]
As shown in FIG. 2, the vane 4 is formed by forming a curved surface portion 4 d having a large curvature radius on the rotation direction side of the rotor 2 at the tip portion of the vane 4. That is, even if the inner peripheral surface of the cam ring 1 has a portion that is in contact with the vane 4 at an acute angle, the tip of the vane 4 is always in contact with the inner peripheral surface of the cam ring 1 at a smooth curved surface portion. The corner portion on the rotational direction side of the rotor 2 is abolished, and an arcuate curved surface portion 4d having a large radius of curvature formed from the rotational direction side of the rotor 2 is provided. In this embodiment, the slit 3 may have a conventional shape.
[0026]
Even if the vane 4 is inclined by the sliding resistance, and the inner peripheral surface of the cam ring 1 has irregularities and has a portion that is in contact with the vane 4 at an acute angle, the tip of the vane 4 has the above-described shape. That is, there is no corner on the rotational direction side of the tip of the vane 4, and the curvature of the vane 4 is sufficiently large with respect to the curvature of the inner peripheral surface of the cam ring 1. The tip of the vane 4 is always in smooth contact, and the vane 4 can slide smoothly on the inner peripheral surface of the cam ring 1. Therefore, it is possible to prevent abnormal noise due to catching between the inner peripheral surface of the cam ring 1 and the vane 4 and to prevent wear of the vane pump itself.
[0027]
FIG. 3 is a schematic configuration diagram of power steering of a vehicle showing an example of a specific application of the vane pump.
[0028]
The power steering is used to assist the steering force when the vehicle is steered, and is particularly effective in reducing the steering force at a low speed and greatly reduces the burden on the driver. The oil pressure compressed by the oil pump is used as a power source for the steering force, and a vane pump is applied as the oil pump.
[0029]
As shown in FIG. 3, the power steering includes a steering wheel 12 that is used by the driver to steer the tire 11, a steering shaft 14 that transmits a steering force applied to the steering wheel 12 to the steering gear box 13, and a steering wheel. Steering force from 12 is assisted by using hydraulic pressure, a steering gear box 13 that steers the tire 11, an oil pump (vane pump) 15 that supplies hydraulic pressure to the steering gear box, and an oil tank 16 that serves as a reservoir thereof are provided. I have. The oil pump 15 uses the rotation of the engine 17 to rotate the rotor of the oil pump 18 using a belt 18 provided between the engine 17 and the oil pump 15. The oil flows as indicated by the arrows shown in FIG. 3 and is pressurized by the oil pump 15 when supplied from the oil pump 15 to the steering gear box 13 to become a power source during steering.
[0030]
In the vane pump according to the present invention, the inner peripheral surfaces of the vane and the cam ring slide smoothly. Therefore, when used in the power steering having the above-described configuration, it is possible to prevent the abnormal noise at the time of stationary operation that has been generated conventionally. The wear of itself can also be prevented. Further, since the sliding resistance is reduced, the load on the engine of the vane pump can be reduced, and the response and fuel consumption of the engine itself can be improved.
[0031]
The drive source for the rotation of the rotor of the oil pump 15 is not limited to the engine 17. For example, in a light vehicle or the like, there is a relationship with the installation space, and the motor 17 may be driven by an electric motor. By reducing the dynamic resistance, the load on the electric motor can be reduced and the power consumption can be reduced.
[0032]
In the above-described embodiment, the present invention is applied to a vane pump for power steering. However, the present invention is not limited to that used for power steering, and can be applied to other hydraulic devices.
[0034]
【The invention's effect】
According to the first aspect of the present invention, even if the vane is inclined, the tip of the vane and the inner peripheral surface of the cam ring are always in smooth contact with each other, so that no abnormal noise is generated. As a result, cam ring and vane wear is reduced and the life of the vane pump is extended. In particular, when the driving source of the rotor of the vane pump is an engine, the engine load is reduced due to the reduction in sliding resistance, and the engine response and fuel consumption are improved. Further, as the weight of the vane tip increases, the inertial force (centrifugal force) also increases, the vane pressing force improves, and the airtightness also improves.
[0035]
According to the second aspect of the present invention, even if the vane is inclined, the tip of the vane and the inner peripheral surface of the cam ring are always in smooth contact with each other, so that no abnormal noise is generated. As a result, cam ring and vane wear is reduced and the life of the vane pump is extended. In particular, when the driving source of the rotor of the vane pump is an engine, the engine load is reduced due to the reduction in sliding resistance, and the engine response and fuel consumption are improved.
[0037]
According to the invention which concerns on Claim 3 , the convex part of a vane front-end | tip can be accommodated in a slit, and the performance as a vane pump is not impaired.
[Brief description of the drawings]
FIG. 1 is a schematic view of a vane shape of a vane pump showing an example of an embodiment according to the present invention.
FIG. 2 is a schematic view of the vane shape of a vane pump showing another example of the embodiment according to the present invention.
FIG. 3 is a schematic configuration diagram of power steering showing an example of specific application of the vane pump according to the present invention.
FIG. 4 is a schematic configuration diagram of a conventional vane pump, (a) is a schematic configuration diagram inside the vane pump, and (b) is an enlarged view of a portion of the vane.
[Explanation of symbols]
1 Cam ring 1a Concave portion (a portion where the radius of the inner peripheral surface greatly changes)
1b Convex part (part where the radius of the inner peripheral surface changes greatly)
2 rotor 3 slit 3c notch 4 vane 4b corner 4c convex 4d curved surface 5 gap

Claims (3)

A cam ring provided with at least one of irregularities whose curvature changes on the inner peripheral surface, a rotor rotating in the cam ring, slits provided radially on the rotor, and a tip thereof disposed in the slit. In a vane pump having a vane in contact with the inner peripheral surface of the cam ring,
A vane pump characterized in that an arcuate convex portion that smoothly moves on the inner peripheral surface of the cam ring is formed on the rotation direction side of the rotor at the tip of the vane. A cam ring provided with at least one of irregularities whose curvature changes on the inner peripheral surface, a rotor rotating in the cam ring, slits provided radially on the rotor, and a tip thereof disposed in the slit. In a vane pump having a vane in contact with the inner peripheral surface of the cam ring,
A curved surface having a radius of curvature sufficiently larger than the radius of curvature of the inner peripheral surface of the cam ring is formed at the tip of the vane so as to smoothly move the inner peripheral surface of the cam ring on the rotational direction side of the rotor. Vane pump characterized by that. The vane pump according to claim 1, wherein
The vane pump characterized in that the slit has a cutout portion formed in accordance with the shape of the convex portion at the tip portion of the vane, and the convex portion can be accommodated.

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