JPS6118002B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automobile vacuum pump used in an automobile brake system, etc.

[Conventional technology]

Conventionally, vacuum pumps used in automobiles have been put into practical use with a displacement of 22 to 120c.c./rev, but the shape of the tip in the vane of these vacuum pumps has nothing to do with the displacement. The vane has a small arc shape with a radius of curvature of 6 mm, and the center of the radius of curvature is located at the center of the thickness of the vane.

[Problem that the invention seeks to solve]

However, the heat generated by the sliding between the tip and the cam surface in these conventional vanes is extremely large, and this heat generation poses important problems in the following points.

When these vacuum pumps are installed in automobiles and used for brakes, etc., the vacuum pumps must be driven effectively within a narrow engine room, so they must be driven by a generator driven by the engine. The configuration is such that it is driven by As a result, the maximum rotation in that drive is
The speed reaches as much as 10,000 rpm, and engine oil is commonly used as a lubricant for the rotating and sliding parts of the tip and cam surface of the vane.

Further, the amount of lubricating oil for the vacuum pump using such engine oil is limited to a very small amount of about 400 c.c./min due to the limited space and weight of the automobile.

As described above, vacuum pumps for automobiles are used by rotating at extremely high speeds and using very small amounts of lubricating oil.

Therefore, after these lubrications, the temperature of the lubricating oil coming out of the vacuum pump at its maximum speed is
The temperature is extremely high, around 180℃.

However, engine oil heated to such a high temperature deteriorates due to rapid oxidation. Therefore, the heat generated by sliding in the chip must be kept as low as possible.

An object of the present invention is to provide a vacuum pump for an automobile in which the amount of heat generated in the vane chip as described above is reduced.

[Means for solving problems]

The present invention consists of the following configuration.

A vane is inserted into a groove cut in the radial direction of the rotor to enable sliding movement in the radial direction, and the shape of the cam surface with which the tip of the vane rotates and slides while in contact is In the above configuration having a circular shape, the shape of the tip is such that: (a) the vane forming the tip is inserted into a line connecting the rotation center of the rotor and the circular center of the cam surface; When the groove is vertically located and the vane is in the compression stroke, a position on the chip opposite to the lubricating oil introduction part from the front surface 3d of the vane in the rotating direction is The chip is in contact with the cam surface, and the contact at the contact portion is such that the surface of the chip that is in contact with the cam surface has an arc shape inscribed in the cam surface in a plane perpendicular to the drive shaft of the rotor; The groove into which the vane forming the chip is inserted is perpendicular to the line connecting the rotation center of the rotor and the circular center of the cam surface, and the vane is in the expansion stroke. At this time, the intersection point m of the rear surface of the vane with respect to the front surface and the tip touches the cam surface, and the surface of the tip that is in contact with the cam surface at the contact portion is driven by the rotor. It has a circular arc shape inscribed in the cam surface in a plane perpendicular to the axis, and (c) the entire surface of the chip from the front surface to the rear surface including the lubricating oil introduction part has a single radius of curvature in the vertical plane. It has an arc shape consisting of the following configuration.

[Effect]

The effects of the configuration of the present invention described above are as follows.

The shape of the tip in the vane of the automotive vacuum pump according to the present invention is as follows: (a) The vane forming the tip is inserted into the line connecting the rotation center of the rotor and the circular center of the cam surface. The grooves are located vertically,
In addition, when the vane is in the compression stroke, a position on the chip that is a predetermined distance away from the front surface in the direction in which the vane rotates and faces the lubricating oil inlet is in contact with the cam surface, and the contact at the contact portion is , the surface of the chip in contact with the cam surface has an arcuate shape inscribed in the cam surface in a plane perpendicular to the drive shaft of the rotor.

Here, in (a), with respect to the line connecting the rotation center of the rotor and the circular center of the cam surface,
When the groove into which the vane that forms the chip is inserted is vertically positioned, and the vane is in the compression stroke, 〓 means that the vane is at its most opposite to the cam surface for each revolution of the rotor. One of two severely inclined positions, and that inclination is such that the frontmost part in the direction of rotation of the tip contacts the cam surface of all the parts where the tip and cam surface contact. It means that it is time.

In this case, the force exerted by the vane tip on the cam surface due to the centrifugal force generated on the vane is:
According to Hertz's theory, it is desirable that the radius of curvature of the chip curved surface in contact with the cam surface be as large as possible.

In addition, for this purpose, it is desirable to effectively utilize the entire surface of the chip so that the entire surface comes into contact with the cam surface one after another.

For this reason, in order to make effective sliding contact with the cam surface of the chip, including the rearmost edge of the chip, it is necessary to connect the rotation center of the rotor with the circular center of the cam surface. When the groove in which the vane forming the tip is inserted is perpendicular to the line, and the vane is in the compression stroke, the front edge of the tip in the direction of rotation of the vane should be aligned with the cam surface. It is desirable that they are in contact with each other.

However, with such a configuration, there is no introduction part for lubricating oil on the front side of the chip facing the direction of travel of the vane, making it impossible to lubricate the sliding surface of the chip. The lip will scrape the lubricant off the cam surface.

For this reason, in the present invention, as an introduction part for the lubricating oil necessary for lubrication, the tip is formed along the line connecting the rotation center of the rotor and the circular center of the cam surface. When the groove into which the vane is inserted is vertical and the vane is in the compression stroke, the vane is spaced a predetermined distance from the front in the direction of rotation, corresponding to the lubricating oil introduction part. The position of the tip is in contact with the cam surface, and the contact at the contact portion is such that the surface of the tip in contact with the cam surface has an arc shape inscribed in the cam surface in a plane perpendicular to the drive shaft of the rotor. I am doing it, I am doing it.

That is, 1. A lubricating oil introduction part of the required minimum length is provided on the front surface in the rotational direction of the chip, and 2. The shape of the chip at the "contact area" of the chip with respect to the cam surface is internal to the cam surface. The arc shape reduces the stress exerted by the tip on the cam due to the centrifugal force generated in the vane.

Also, what should be noted here is that the centrifugal force is a very large value because the rotor speed is over 10,000 rpm.

Furthermore, the shape of the tip of the vane of the automotive vacuum pump according to the present invention is determined by the following: (b) The shape of the vane forming the tip with respect to the line connecting the rotation center of the rotor and the circular center of the cam surface. When the groove is located vertically and the page is in the expansion stroke, the intersection of the rear surface of the page with the front surface and the tip touches the cam surface, and the contact at the contact part also touches the cam surface. The surface of the chip is in the shape of an arc inscribed in the cam surface in a plane perpendicular to the drive shaft of the rotor.

Here, the groove in which the vane forming the chip is inserted is located perpendicular to the line between the rotation center of the rotor and the circular center of the cam surface, and the vane is in the expansion stroke. When, 〓 means 2 above when the vane is most severely inclined with respect to the cam surface.
The other position is shown, and the direction of inclination means the position where the rearmost edge of the tip in the rotation direction of the vane contacts the cam surface among the parts where the tip contacts the cam surface. .

In other words, in this state, the contact portion between the tip and the cam surface is such that the rearmost end in the rotating direction of the portion where the tip and the cam surface are in contact is in contact, and the front end is away from the cam surface. In this state, sufficient lubricating oil is introduced into the chip.

Therefore, in this state, the rearmost edge of the tip in the advancing direction (the ``intersection m of the rear surface of the vane with respect to the front surface in the advancing direction and the tip'') is in contact with the cam surface.

Also, the tip "contact part" to the cam surface.
Similarly to the above, the shape of the tip is also an arcuate shape disposed within the cam surface, so that the stress exerted by the tip on the cam surface due to the centrifugal force generated in the vane is reduced.

As a result, the shape of the chip covers the entire surface of the chip, including the rearmost edge of the chip, except for the minimum required lubricant introduction part provided at the front in the forward direction of the rotor for each rotation of the rotor. All will come into effective sequential contact with the cam surface.

This means that all of the tip surfaces sequentially move from the front side to the rearmost edge and come into contact with the cam surface, which increases the flat area in contact with the cam surface, reducing tip fatigue. I will let you do it.

Furthermore, c) the surface of the chip, including the lubricating oil inlet, from the front surface in the direction of travel to the rear surface in the direction of travel has an arc shape with a single radius of curvature in a plane perpendicular to the rotor rotation axis; There is. 〓 It has become a thing.

This means that even at each of the positions where the vane is most inclined, the tip shape has its own curvature with respect to the cam surface, but these curvatures are the same shared curvature. It also shows that the entire surface of the chip, including the lubricating oil inlet, can form a single circular arc.

Therefore, forming the entire area of the chip with a single curvature in this way makes it possible to effectively utilize the surface of the chip and maximize its curvature. This means that the surface pressure on the surface is reduced, and the heat generated during sliding is also reduced.

The fact that the chip can be formed by a single circular arc while satisfying all of the above conditions has been proven in the theoretical analysis in the Examples described later.

In addition, in this case, the shape of the tip is such that the lubricating oil introduction part is provided on the front side in the direction of movement, and the rear side in the direction of movement is all in contact with the cam surface. All of the parts behind it form a single arc.

This indicates that the center of the radius of curvature is shifted rearward from the center in the thickness direction of the vane, which is different from the conventional case where the center of the radius of curvature is at the center of the thickness of the vane. There is.

〔Example〕

Hereinafter, the present invention will be explained based on Examples.

FIG. 1 shows a side sectional view of an automobile vacuum pump as an embodiment of the present invention, and FIGS. 2 and 3 are enlarged side sectional views of the vane 3 in FIG. The figures are shown in each figure.

In FIG. 1, the cam surface 1a cut into the housing 1 has a circular shape from center 0 to R1.
The rotor 2, which is eccentrically supported in the housing 1, has an outer diameter R2, and has an offset amount perpendicular to the eccentric direction of the rotor 2 and parallel to an imaginary plane formed in the rotation axis direction of the rotor 2. At the position eo, a groove 2a is cut centering on the position, and the groove 2a is
A vane 3 that enables sliding movement in the same radial direction as the imaginary plane is inserted into a, and the shape of the tip 3a of the vane 3 is centered on point K within the plane shown in Fig. 1. It forms an arc with radius r.

The displacement chambers 4, 4 formed by the cam surface 1a, the rotor 2, and the vanes 3 are configured to repeatedly expand or compress as the rotor 2 rotates, and as a result, perform a vacuum pump action. It is becoming.

In the configuration of the embodiment of the present invention described above The effect will be explained below.

When the rotor 2 is driven by the engine in the direction of arrow 5, each vane 3 is guided to the cam surface 1a by rotation in the direction of arrow 5 while applying a pressing force to the cam surface 1a by centrifugal force. While being moved, the sliding movement in the radial direction within the groove 2a is repeated, and as a result, the displacement chamber 4 located on the lower side of FIG. Displacement chamber 4 that inhales and conversely reaches the upper side of Figure 1
discharges the sucked air into a discharge hole (not shown), and in the pumping action, the tip 3a and the cam surface 1
a, or between the vane 3 and the groove 2a, engine oil is jetted in the form of a mist from a jet hole (not shown) to lubricate the space between the vane 3 and the groove 2a. It is cooled in the engine oil cooling circuit.

In the above-mentioned action, the rotational sliding between the tip 3a of the vane 3 and the cam surface 1a will now be considered.

The thickness t of the vane 3 in the direction of rotation of the vane 3 (direction of arrow 5) is normally about 4 to 8 mm, and this is due to the centrifugal force of the vane 3 rotating at high speeds ranging from several thousand revolutions per minute to more than 10,000 revolutions per minute. By pressing the tip 3a against the cam surface 1a, the curvature of the tip 3a is brought as close as possible to the curvature of the cam surface 1a, and the full width of the thickness t of the vane 3 is effectively used to apply the tip to the cam surface 1a. Chip 3a can be used by bringing it into contact and reducing the surface pressure on the contacted surface.
This will reduce the amount of heat generated.

However, as is clear from the illustration in FIG. 1, the vane 3 has a different inclination angle with respect to the normal jo or mo of the cam surface 1a as its rotation angle changes. The curvature cannot be made the same as the curvature of the surface 1a.

For this reason, the tip 3a is attached to the cam surface 1a.
If the shape is designed with a radius of curvature as large as possible within a range smaller than the radius of curvature, the surface pressure can be minimized.

In addition to maximizing the radius of curvature mentioned above,
In the front portion of the tip 3a in the traveling direction 5 of the vane 3, lubricating oil is introduced so that the tip 3a can perform a fluid bearing action, which reduces the sliding friction between the tip 3a and the cam surface 1a. This is an appropriate configuration for reducing resistance, and the feature of the present invention is to set the radius of curvature of the entire surface of the chip to the maximum value that can be adopted, and to set the radius of curvature to a single curvature including the lubricating oil introduction part. At the same time, the portion of the tip that comes into contact with and slides on the cam surface of the tip becomes wider, thereby reducing the fatigue of the tip surface due to the contact and sliding.

The maximum possible value of the radius of curvature r will be discussed below.

As mentioned above, in order for the vane 3 to effectively adopt the full width in the advancing direction of the thickness t and slide in contact with the cam surface, the vane 3 must be in the most inclined state with respect to the normal line of the cam surface 1a. In the above, the radius of curvature of the chip shape in the state of the arc where the end (front edge or rear edge) of the chip 3a is smooth with respect to the cam surface 1a, that is, in the most inclined state, is:
The contact position must have a radius of curvature internal to the cam surface 1a, and the smoothly touching circular arc must be the maximum value of the radius of curvature r that can be adopted in the chip. .

As can be seen from FIG. 1, the state in which the vane 3 is most inclined with respect to the normal to the cam surface 1a is the state in which the vane 3 is perpendicular to the eccentric direction reference line 2b of the rotor 2. This also means that even if the vane 3 is tilted in the groove 2a by considering the gap between the vane 3 and the groove 2a, the vertical position within the error range , it can be seen that the vane 3 is most inclined with respect to the normal to the cam surface 1a.

Among the states of the vane 3 shown in FIG. 1, which are the most inclined, the lower vane 3 is in a state where it is easy to introduce lubricating oil between the tip 3a and the cam surface 1a (corner point m is the cam surface). It can be seen that the vane 3 in the upper position is in a state in which the frontmost side of the tip 3a in the rotational direction is in contact with the cam surface 1a.

Therefore, in principle, the tip 3 is designed so as to minimize the contact pressure between the tip 3a and the cam surface 1a by maximizing the radius of curvature of the tip 3a.
In this structure, even when the vane 3 is in the upper position in FIG. Front 3
If the area at distance tc from d is left as a lubricating oil introduction part, and the remaining area between i and m of tip 3a is a part that effectively contacts cam surface 1a, the contact pressure between cam surface 1a and tip 3a is The smallest and chip 3
This means that the bearing capacity of the a-plane can be increased.

What is important here is that the entire tip surface up to the rearmost edge of the tip 3a should be in contact with the cam surface 1a, except for the lubricating oil inlet at the front edge of the tip 3a. This will maximize the curvature of the chip 3a.

FIG. 2 is an enlarged view of the state in which the vane 3 is in the vertical state and is in the compression stroke where the vane 3 compresses the displacement chamber 4 on the upper side of FIG. 1, as described above. This shows a case where the inclination of the vane 3 in the groove 2a is in the direction of enlarging the left displacement chamber 4.

On the other hand, depending on the operation of this vane pump motor, the slope of the vane 3 with respect to the groove 2a may be in the opposite direction to that shown in FIG. 2. Tip 3a for tilt
This corresponds to a case where the operation is easy because the direction increases the radius r.

Therefore, the shape of the tip 3a can be determined by determining the radius r for the direction of inclination of the vane 3 in the severe condition shown in FIG.

Note that, as is clear from the structure of FIG. 2, the length of the vane 3 guided in the groove 2a is short on the 2c side of 2a and long on the 2d side. The side is "short sliding surface"
The long side 2d is named "long sliding surface".

In the state shown in FIG. 2, the vane 3 is inclined with respect to the normal line o to j to the cam surface 1a, and
In order to achieve the above-mentioned ideal, the shape of the tip 3a at the contact point j (the frontmost part of the tip 3a in contact with the cam surface 1a) that is in contact with the cam surface 1a must be in the form of a circular arc that is in contact with the cam surface 1a. The center k of the arc must lie on the normal line o to i.

The location of center k will be discussed below.

In FIG. 2, we focus on the triangle formed by normal lines o to j, eccentric direction reference line 2b, and j to fo parallel to the front surface 3d of vane 3, and in the triangle j, fo, and o, passing through the center k In addition, a straight line j·o·fo parallel to the eccentric direction reference line 2b, a triangle j·o·fo and a triangle j·k·ho are similar.

Therefore, jk/jo=ho・k/fo・o (1) where jk=r jo=R1, ho・k=t4 and fo・
Since o=x1, rearranging equation (1) results in r=R1×t4/x1 (2).

Next, find the unknown x1 in the 2 equations.

Triangle abc and triangle cde are similar, and the length of c to b is approximately the difference in length between groove 2a and vane 3 in the rotor rotation direction.
It can be considered that to−t=c1.

Therefore, d1/e1=(to-c1)/c2 or C2=(to-c1)×c1/d1 (3) Also, since triangle abc and triangle egf are similar, d1/c1=(d2+c2)/ c3 Therefore, c3=(d2+c2)×c1/d1 (4), and substituting equation (3) into equation (4), c3={(c1/d1) ² ×(to−c1)} +{( c1/d1)×d2} (5)

Here, the length of f・o is (c3+xo) and the length of f・fo is (t2−t4), so x1=(c3+xo)−(t2−t4) or x1={(c1/d1) ² ×to−c1)} +{c1/d1)×d2}+xo−(t2−t4) (6) is obtained.

Also, as is clear from Figure 2, (t2−t4)
is approximately equal to tc, so equation (6) becomes x1≒{(c1/d1) ² × (to−c1)} + {(c1/d1)×d2}+xo−tc (6a).

Substituting equation (6a) into equation (2) above, equation (2) becomes r
Since it includes two unknowns, r and t4, a new relational expression for r and t4 is determined below.

The radius of curvature at the tip 3a of the vane is set to a constant value r, and since the tip 3a always slides and rotates in contact with the cam surface 1a, the center of curvature k
will move on a circumferential circle 3b centered on center 0, as shown in FIG.

The vane 3 is perpendicular to the eccentric direction reference line 2b, and the vane 3 is located in the displacement chamber 4 on the lower side of FIG.
When the vane 3 is in the expansion stroke position (the position of the vane 3 in the defect shown in Fig. 1)
is the other state where it is most inclined with respect to the cam surface 1a, so at this time, the corner point m of the tip 3a must be in contact with the cam surface 1a, and the curvature of the side of the tip 3a at the contacting portion is as described above. must have radius r.

Moreover, at this time as well, the center k of the radius r exists on the circumferential circle 3b.

FIG. 3 shows an enlarged view of the vane 3 located on the lower side in FIG. 1, and as is clear from FIG. 3, corner point m is also The center k of the radius r is the cam surface 1a
It must be located at the intersection of the normal line mo from the corner point m and the circumferential circle 3b.

Here, n is parallel to the eccentric direction reference line 2b.
If ~k is provided, a triangle similar to that in Fig. 2
mso and triangle mnk are similar.

Therefore, y1/om=t3/km (7), and since om=R1 and km=r, rearranging equation (7) gives r=R1×t3/y1 (8).

Here, y1=yo−c4 (9), and since c4 is an unknown number, the following unknown number c4 is found from Figure 3. Since triangle auv and triangle aqs are similar, c1/d3=c4/(d3+d4) or c4=c1×(d3+d4)/d3 (10).

Therefore, from equations (9) and (10), y1=yo−(c1/d3)×(d3+d4) (11) get.

Also, consider t3 in equation (8).

Since the length of the normal ki extending from the center k to the side of the vane 3 is assumed to be t20 as shown in Figure 2, the length of kp extended from the normal ki is t-t20.
(Figure 3), and since triangle knp (Figure 3) and triangle khi (Figure 2) are similar, t20/t2 = (t-t20)/t3 or t3 = t2 x (t-t20) /t20 (12), and as is clear from Figure 1, t2≒t20 (13) Therefore, equation (12) can be written as t3≒t−t20 (14).

Therefore, from equations (8) and (14), we obtain r=R1×(t-t20)/y1 (15). Similarly, since t4 and t40 are approximately equal, equations (2) and (13) Therefore, r=R1×(t20−tc)/x1, and finally from equations (15) and (16), t20=(X1・t+y1・tc)/(x1+y1) (17) and r=R1×(t -tc)/(x1+y1) (18) In equations (17) and (18), x1 and y1 can be found from equations (6a) and (11).

What should be noted here is that in equation (17), t
20 is not equal to 1/2 of the thickness t of the vane 3. This means that in the conventional method t20 (distance from the vane front surface where the center of the chip curvature radius is located) is equal to 1/2 of the vane thickness t. It is different from what it used to be.

In addition, since the radius of curvature r has a value smaller than the circular radius R1 of the cam surface 1a, for each contact point at the extreme position where the vane 3 at point j and point m is most inclined, Even at the position of the vane 3 corresponding to
It will slide while making smooth contact with the surface.

From the above calculation results, the center k of the radius of curvature r in the chip 3a can be found from equations (17) and (18), and when actually designing the shape of the chip 3a, use equation (18). The calculated radius r
With the value of
A parallel line is provided from the front surface 3d of the vane to the front surface 3d with a dimension of 0, and the intersection of the parallel line and the arc becomes the center k to be determined.

In the above configuration, if the distance tc from the front surface 3d of the vane 3 to the contact point j is set to a too large value, the radius of curvature r of the tip 3a will be reduced to increase the contact pressure at which the tip 3a contacts the cam surface 1a. The appropriate value for distance t is vane 3.
20% or less of the thickness t in the direction of rotation, especially 5
It is desirable that the lubricating oil introduction part in the tip 3a is the shortest in the state shown in FIG. Since the length is longer than the value of tc, lubricating oil is always introduced into the tip 3a.

In addition, in the embodiment of the present invention, the second
The configuration is such that x1 in the figure is located to the left in the figure, but the offset amount eo of the vane 3 is even larger than in the embodiment of the present invention, and the direction of the value of x1 is as shown in FIG. It will be easily understood that the tip shape of the vane 3 can be calculated using the same idea as above even when the tip is to the right or when the offset amount eo is zero.

To summarize the above analysis, 1. Of the two positions where the vane 3 is most inclined, a: point j, where the eccentric front part of the tip 3a comes into contact with the cam surface 1a, excluding the lubricating oil introduction part, and b. :The rearmost edge of the chip 3a is the cam surface 1
At both contact points j and m with the position m where the chip 3a comes into contact, the radius of curvature with which the chip 3a comes into contact is an arc located inside the cam surface 1a, and 2. The frontmost part of the chip 1a 3. In addition, the radius of curvature r of the chip 3a is such that the entire chip surface, including the lubricating oil introduction part, can be formed by a single radius of curvature. This proves that it can be achieved.

FIG. 4 shows two types of vacuum pumps 11 and 21.
Heat generation ratio (ratio to maximum heat generation) of the entire vacuum pump when conventional vanes are attached to Q
In the figure, 12 and 22 indicate the experimental values of the calorific value ratio Q when the vane 3 of the present invention is attached to the vacuum pumps 11 and 21, respectively.

Here, the tip shape of the vane 3 in the present invention has a radius of curvature r of 9 mm, whereas the radius of curvature r of the conventional tip is 6 mm.
In comparison, the radius of curvature r in the present invention is increased by 50% compared to the conventional one.

In addition, in the above experimental values, 1 for 11
This is an improvement of 22, compared to 21. As a result, from FIG. 4, it can be seen that the vane 3 of the automotive vacuum pump according to the present invention improves the calorific value of the entire vacuum pump by approximately 20% compared to a vacuum pump using a conventional vane.

〔Effect of the invention〕

As is clear from the above description, the automotive vacuum pump of the present invention has a tip shape in the vane, except that the minimum necessary lubricating oil introduction part is provided on the front side in the direction of tip movement. When the surface rotates once, the entire surface of the chip up to the rear end in the direction of travel comes into effective and smooth contact with the cam surface, forming an arc formed within the cam surface.

Therefore, the radius of curvature of the chip is set to be the maximum that effectively brings the entire chip into contact with the cam surface sequentially, excluding the lubricating oil introduction part.
The surface pressure between the tip and the cam surface is reduced, the heat generated during sliding is also reduced, and the power loss is reduced by 20% as shown in Figure 4.

In addition, as for the chip sliding surface, all the chip surfaces up to the rearmost part in the direction of movement, excluding the lubricating oil introduction part, are used as contact sliding surfaces sequentially as the chip rotates, so the cam surface on the chip The portion that shares the sliding contact with the chip increases, and as a result, the fatigue of the chip due to the sliding is reduced, and the durability of the chip is improved.

Moreover, the chip shape, including the lubricating oil introduction part, has a circular arc shape with a single radius of curvature. This process can be completed by multiple machining steps, and there is no need for additional machining such as chamfering the lubricating oil introduction part of the chip, which simplifies the machining process. This will simplify the mass production process.

Furthermore, when the automotive vacuum pump of the present invention is installed in an automobile and conventional engine oil is used to lubricate the chips in the vanes, the temperature rise of the lubricating oil can be kept low as described above. , the engine oil cooler can be used without making it particularly large.

In addition, the fact that the cooler does not need to be too large is advantageous in terms of the use of limited space in the engine room, the weight of the cooler, and the manufacturing cost. This not only improves the operating efficiency of vacuum pumps, but also contributes to reducing vehicle fuel consumption.

Furthermore, the automotive vacuum pump according to the present invention includes:
It has the following effects.

The stress applied to the vane is determined by the bending moment in the rotational direction, and the bending moment is determined by the sliding resistance between the tip and the cam surface.

Therefore, as mentioned above, if the sliding resistance between the tip and the cam surface becomes smaller, it becomes possible to further reduce the thickness of the vane. Since the weight of the vane is further reduced, the centrifugal force of the vane caused by the high-speed rotation (maximum 10,000 rpm or more) mentioned above is further reduced, which further reduces the sliding resistance on the tip and cam surface. This makes it possible to further reduce heat generation due to sliding.

[Brief explanation of the drawing]

FIG. 1 shows a sectional side view of an automobile vacuum pump as an embodiment of the present invention, and FIG.
3 and 3 respectively show an enlarged side sectional view of the vicinity of the vane 3 in FIG. 1, and FIG. 4 shows the amount of heat generated by the conventional vacuum pump and the vacuum pump of the present invention. This shows the characteristics of the ratio Q. The symbols used in the examples of the present invention are as follows. 1: Housing, 1a: Cam surface, 1b: Reference line, 2: Rotor, 2a: Groove, 2b: Eccentric direction reference line, 2c: Short sliding surface, 2d: Long sliding surface, 3: Vane, 3a: Chip , 3b: circumference, 3c: bottom, 3
d: Front surface in the rotational direction of the vane 3, 4: Displacement chamber, 5: Arrow, R1: Radius of curvature of the cam surface 1a,
R2: outer diameter (radius) of rotor 2, eo: offset amount of vane 3, r: radius of curvature of chip 3a,
xo: dimension from reference line 1b to long sliding surface 2d, yo: dimension from reference line 1b to short sliding surface 2c, otsubi k: center, t: thickness of vane 3 in rotational direction, to :Thickness of the groove 2a in the rotational direction, t20:
The length of the perpendicular line drawn from the center k to the side of the vane 3,
tc: minimum length of lubricating oil introduction part in chip 3a, a, b, c, d, e, f, fo, g, h, ho,
i, j, m, n, p, q, s, u and v: points,
d1 and d3: length guided in the groove 2a of the vane 3, d2 and d4: bottom 3 of the vane 3
Length from c to eccentric direction reference line 2b.

Claims (1)

[Claims] 1. A vane is inserted into a groove cut in the radial direction of the rotor so as to be able to slide in the radial direction, and the tip of the vane rotates and slides while being in contact with the vane. In the above configuration in which the shape of the cam surface is circular, the shape of the tip is a) The tip is formed with respect to a line connecting the rotation center of the rotor and the circular center of the cam surface. When the groove into which the vane is inserted is located vertically, and the vane is in the compression stroke, a predetermined distance tc from the front surface 3d of the vane in the rotating direction facing the lubricating oil introduction part is provided. A position on the chip contacts the cam surface, and the contact at the contact portion is such that the surface of the chip that is in contact with the cam surface forms an arc inscribed in the cam surface in a plane perpendicular to the drive shaft of the rotor. (b) the groove into which the vane forming the chip is inserted is located perpendicular to a line connecting the rotation center of the rotor and the circular center of the cam surface; When the vane is in its expansion stroke, the intersection point m of the rear surface of the vane with respect to the front surface and its tip is in contact with the cam surface, and the surface of the tip in contact with the cam surface is in contact with the cam surface at the contact portion. has an arc shape that is inscribed in the cam surface in a plane perpendicular to the drive shaft of the rotor, and (c) the entire surface of the chip from the front surface to the rear surface including the lubricating oil introduction part is within the vertical plane. A vacuum pump for use in an automobile, characterized in that it has an arcuate shape with a single radius of curvature.