JPH01159479A - Pump structure for automobile - Google Patents

Abstract

PURPOSE:To improve sealing performance by letting a seal member possess a thermal expansion coefficient wherein thermal expansion characteristics exhibited by both the seal member and a rotor are approximately identical to those of a housing in a pump provided with the seal member in a recess formed in the sliding surface of the rotor. CONSTITUTION:In a trochoid type oil pump wherein an outer rotor 22 having an internal gear is rotatably coupled within a housing 2 and an inner rotor having an external gear meshed with the aforesaid internal gear is coupled with the outer rotor, the housing 2 is made of light alloys such as aluminum alloys and the like, and the outer rotor 22 is made of iron, for example, sintered materials. In addition, a circular seal member 24 is coupled with a circular recess 22a formed in the sliding surface of the outer rotor 22. In this case, the seal member 24 shall be made of, for example, teflon having a thermal expansion coefficient wherein thermal expansion characteristics exhibited by both the seal member and the outer rotor 22 are approximately identical to thermal expansion characteristics of the housing 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automobile pump structure having an iron rotor that slides within a housing made of a light alloy material.

(Prior Art) For example, as described in Japanese Unexamined Patent Publication No. 61-108884, an outer rotor having internal teeth is rotatably fitted in a housing, and external teeth are provided to engage with the internal teeth of the outer rotor. A trochoid type oil pump in which an inner rotor is fitted into the outer rotor is known.

Specifically, such an oil pump is constructed as shown in FIGS. 7 and 8, for example. That is,
A trochoid-type oil pump 1 includes an inner rotor 6 rotatably driven by an eccentric shaft in a cylindrical space 3 formed in the center of a housing 2, and an outer periphery formed in a cylindrical space 3.
An outer rotor 8 is provided which is rotated in the same direction as the inner rotor 6 rotates while being in sliding contact with the inner circumferential wall of the inner rotor 6 .

The inner rotor 6 includes ten external teeth 4 having a tooth shape formed by a trochoidal envelope, while the outer rotor 8 includes eleven internal teeth 7 that engage with the external teeth 4. In addition, in the trochoid type oil pump 1, the external teeth 4
is always one more than the number of internal teeth 7.

The tooth tip of each external tooth 4 of the inner rotor 6 is always in sliding contact with one of the internal teeth 7 of the outer rotor 8, so that the external tooth 4, the internal tooth 8, and the side wall of the space 3 of the housing 2 and the pump Ten oil chambers 11 that do not communicate with each other are formed by the inner surface of the cover 9. These oil chambers 1
1 rotates around an eccentric axis with the rotation of the inner rotor 6, and increases the volume of the suction port 12 when it is in a position communicating with the suction port 12.
Oil is sucked in from the oil suction passage 13 through the oil suction passage 13, and when it passes through the leading end of the suction port 12, its volume reaches its maximum, trapping the oil.After this, when it reaches the position where it communicates with the discharge port 14, the oil is sucked in as it rotates. A series of steps of discharging oil to the oil discharge passage 15 through the discharge port 14 while decreasing the volume is continuously repeated, so that the oil is supplied to a predetermined device at a predetermined discharge pressure (for example, 20 kg/ad). It has become. Note that oil is introduced into the trochoid pump from an oil tank (not shown) through an inlet 16, and is supplied from the trochoid pump to a predetermined device through an outlet 17. Also, between the housing 2 and the outer rotor 8 and between the inner rotor 6 and the central boss portion 2a of the housing 2,
An outer sleeve 18 and an inner sleeve 19 are interposed between the two. 2o is a bearing metal.

In such a device, the housing 2 is made of cast iron (coefficient of thermal expansion α□=11.5×10″″67°C), and the rotor 6.8 is made of sintered metal (coefficient of thermal expansion αZ=11°5×
10-6/℃), and the difference in thermal expansion coefficient between the two is small, so the side clearance (the difference between the thermal expansion characteristics of the housing and the outer rotor) is almost constant regardless of the temperature state. can be kept. In other words, as shown in Figure 9, if the assembly temperature is 20°C and the side clearance is set to 20μ, the temperature will be between -30°C and
The side clearance is 20μ in the operating range of 160℃.
Almost constant.

Incidentally, in oil pumps for automobiles and the like, attempts have been made to form housings of aluminum alloys (thermal expansion coefficient α3=23.0×10 −6 /° C.) for the purpose of weight reduction.

(Problem to be solved by the invention) However, if the housing is made of aluminum alloy in this way, the rotor is made of sintered metal, and the ratio of thermal expansion coefficients of aluminum alloy and sintered metal becomes 2:1. For,
The side clearance changes greatly due to temperature changes (see Figure 10).

Therefore, if the side clearance at 20°C is set small in order to reduce leakage at high temperatures around 160°C, the minimum clearance at the seizure limit cannot be maintained at low temperatures around -30°C. On the other hand, if the setting is made to maintain the minimum clearance of the seizure limit, leakage at high temperatures will increase and the discharge pressure will not increase sufficiently.

The present invention has been made in view of these points, and satisfies the two contradictory demands of reducing the change in side clearance between the housing and the rotor, and preventing an increase in leakage at high temperatures and preventing seizure at low temperatures. The object of the present invention is to provide an automobile pump structure that can perform the following steps.

(Means for Solving the Problems) In order to achieve the above problems, the present invention provides a pump structure having an iron rotor that slides inside a housing made of a light alloy material. A recess is formed, a sealing member is provided in the recess, and the thermal expansion characteristics of the sealing member and the rotor at the portion where the sealing member is provided are different from the thermal expansion characteristics of the housing and the path-to-path.
It is characterized by:

(Function) The thermal expansion characteristics of the seal member and the rotor in the area where the seal member is provided are the same as those of the housing, so even if a temperature change occurs, the seal member will maintain the relationship between the housing and the rotor. The gap (side clearance) between the two sides can be kept approximately constant.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 - In FIG. 1 showing the main parts of an outer rotor, 21 is a housing, 22 is an outer rotor, and 23 is an outer sleeve. The housing 21 is made of aluminum alloy (thermal expansion coefficient α3=23.OX 10''/'C), and the outer rotor 22 is made of sintered metal (thermal expansion coefficient α2=11.5X
10-'/"C).

Further, the outer rotor 22 has an annular recess 22a formed in its sliding surface, and an annular seal member 24 is fitted into the recess 22a. The sealing member 24 has a thermal expansion coefficient Q□ between it and the outer rotor 22 which is between the thermal expansion characteristic Q2 of the housing 21 as shown in FIG. 2, such as Teflon (thermal expansion coefficient α). ,
= 100 x 10-6/'C).

In addition, in FIG. 2, Q3 is the thermal expansion characteristic of only the seal member 24, and Q is the thermal expansion characteristic of only the outer rotor 22.

Therefore, thermal expansion of the housing 21 and outer rotor 2
The sum of the thermal elongations of the seal member 2 and the seal member 24 is approximately equal in the thickness direction regardless of temperature changes.

For example, in the case shown in FIG. 2, at an assembly temperature of 20° C., the thickness H of the housing 21 is 14.020 m, the thickness hg of the outer rotor 22 is 12.180 mm, and the seal member 24 is
The thickness ht is 1.82on, and their sum hg + h
t is 14,000 mm.

Note that the side clearance of the 7 outer rotor 22 in the area where the seal member 24 is not provided is approximately 8 at -30°C.
Since μ becomes smaller, it is necessary to set the value to 28μ, taking into account a shrinkage margin of 8μ.

In other words, the side clearance of the outer rotor 22 is
When set to 20μ at 20℃, the thermal expansion characteristic Q5 in Figure 3
As shown in , it becomes smaller as the temperature decreases, and -30
At ℃, the side clearance is 12μ. Therefore,
In order to ensure a side clearance of 20μ at -30℃, it is set to 28μ at 20℃, and the thermal expansion characteristic Q6
As shown in FIG. 2, the dimensions of the outer rotor 22 must vary in the thickness direction.

As a result, the side clearance between the housing 22 and the seal member 24 can be maintained at a constant value of 20μ regardless of the temperature, and the clearance with the outer rotor 22 will not become smaller than 20μ.

In the first embodiment, the side clearance at the assembly temperature of 20° C. is made different between the part with the seal member 24 and the part without it, but it can also be made the same as in the second embodiment.

Embodiment 2 - In this example, as shown in FIG.
By setting it to 28μ at 0'C, a side clearance of 20μ is secured at -30℃, and a side clearance of 28μ at 160℃ is ensured.
μ can be maintained.

In this example, the seal member 31 is attached to the recess 3 of the outer rotor 32.
2a and then simultaneously ground and assembled at 20°C with a predetermined side clearance, the side clearance is about 8μ larger at 160°C than in Example 1 above, but the ease of assembly is improved. will improve.

In addition, in this example, the side clearance is -30℃~2
In the range of 0°C, only the outer rotor 32 (see thermal expansion characteristic Q6 in Fig. 5) is present, and in the range of 20°C to 160°C, the part of the outer rotor 32 and seal member 31 (see thermal expansion characteristic Q7 in Fig. 5) ), respectively.

Example 3 - In this example, Example 2 is further improved to increase the side clearance at 160°C from 28μ to 20μ.

That is, in Example 2, the set side clearance at 20°C is 28μ, and when the temperature rises from 20°C to 160”C, the elongation of the housing 21 is δ=45°1μ (=14×2
3xto-6X(160-20)).

Therefore, in order to set the side clearance at 160°C to 20μ, the elongation of the outer rotor 32 and seal member 31 due to the temperature increase from 20°C to 160”C is 28μ+(45,1-20)μ=53. It must be bound by 1μ. Therefore, if the thickness of the sealing member 31 is one stroke, then Z X cz4X (160-20) + (14-χ)
1χ=2.47+om. As a result, the thickness of the sealing member 31 is reduced to 2.4
7m+, the thickness of the outer rotor 32 is 11.53mm
(=14-2.47), the relationship shown in FIG. 6 is obtained.

Therefore, in the range of -30°C to 20°C, the side clearance is determined by the portion of only the outer rotor 32 (see thermal expansion characteristic Q6 in FIG. 6), and in the range of 20°C to 160°C, the side clearance is determined by the portion of the outer rotor 32 and the seal member 31. (See thermal expansion characteristic Ω8 in FIG. 6).

(Effects of the Invention) Since the present invention is configured as described above, changes in the side clearance between the housing and the rotor due to temperature changes are reduced, and an increase in leakage amount at high temperatures and seizure at low temperatures are prevented. be able to.

[Brief explanation of the drawing]

1 to 6 show embodiments of the present invention. FIG. 1 is a diagram showing the relationship between the rotor and the seal member of the first embodiment, and FIGS. 2 and 3 are diagrams showing the relationship between the rotor and the seal member of the first embodiment. A diagram showing the relationship between temperature and dimensional change, FIG. 4 is a diagram showing the relationship between the rotor and sealing member of Example 2, and FIGS. 5 and 6 are temperature and dimensions for Example 2 and Example 3. Figures 7 and 8 are front views and longitudinal sectional views of a trochoidal oil pump, and Figures 9 and 10 are diagrams showing the relationship between temperature and dimensional changes for conventional examples. It is. 21... Housing, 22, 32...
Outer rotor, 22a... recess, 24, 31.
... Seal member. Figure 7 Figure 9 Figure 10

Claims (1)

[Claims] (1) In a pump structure having an iron rotor that slides inside a housing made of a light alloy material, a recess is formed in the sliding surface of the rotor, a seal member is provided in the recess, and the seal member is A pump structure for an automobile, characterized in that the thermal expansion characteristics of the seal member and the rotor in the provided portion are substantially the same as the thermal expansion characteristics of the housing.