JPS60173387A - Mechanical supercharger - Google Patents

Abstract

PURPOSE:To enable the resin coating of the peripheral surface of the rotor of a mechanical supercharger provided in the intake line of an internal-combustion engine, without performing a substrative treatment on the peripheral surface, and to improve the pump efficiency of the supercharger, by using a copolymer of ethylene tetrafluoride and ethylene to coat the peripheral surface of the rotor. CONSTITUTION:The rotor 10 of a Root's supercharger has a center hole 20 for fitting the rotor on a shaft, and openings 21 for reducing the weight of the rotor. The peripheral surface and both end faces of the aluminum-made rotor having the center hole 20, the openings 21 and a prescribed contour are coated with resin at 23, 24. At that time, the resin enters into the openings 21. The resin is a copolymer of ethylene tetrafluoride and ethylene. For that reason, the coating can be easily performed on the surface of the rotor 10 without carrying out a substrative treatment on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a mechanical supercharger commonly used in internal combustion engines.
゜Prior art Mechanical superchargers are mechanically connected to the crankshaft 71 of the engine, and are glazed pumps, such as vane pumps and Roots pumps. In the loop pump,
The two rotors are driven synchronously with a small clearance so that they are in close contact with each other, thereby performing a pumping action.

It is known to coat the outer circumferential surface of such a rotor with resin, and by resin coating, the minute clearance between the rotors can be made much smaller, and the pump efficiency can be improved. However, the outer circumferential surface of such a rotor has a portion that curves inward in the radial direction, and the coated resin expands and contracts due to repeated cooling and heating cycles of the engine, and peels off from the rotor base material at the aforementioned inwardly curved portion. There is a problem. Therefore, the coating resin for the rotor of a mechanical supercharger is required to be heat resistant and difficult to peel off. Nylon, tetrafluoroethylene, etc. are commonly considered as such resin forest materials. However, it has been found that nylon cannot be used for high-speed, high-pressure supercharging because it does not meet both of the above requirements. Although tetrafluoroethylene is heat resistant, it is easily peeled off, requiring special surface treatment on the surface of the rotor base material, which increases manufacturing costs.

Object and Structure of the Invention In view of the above, the object of the present invention is to coat the rotor of a mechanical supercharger with resin to improve pump efficiency, and to make it possible to perform the resin coating at low cost and to replace the previously coated resin with the rotor base. The purpose is to make it difficult to peel off from the material. This objective is achieved by using a tetrafluorinated ethylene-ethylene copolymer resin.

DESCRIPTION OF THE EMBODIMENTS In FIG. 1, an intake passage 2 and an exhaust passage 3 are connected to an engine body 1 in a known manner. The intake passage 2 includes an air cleaner 4, an air 70-sensor 5, a throttle valve 6, a supercharger 7, a large tank 8, and a twisted material injection valve 9.
etc. are arranged.

The supercharger 7 of this embodiment utilizes a Roots pump and has two rotors JO with a bilobal cross section. The cross section of the rotor 10 can also be made into other shapes, such as a trilobal shape, and the supercharger is not limited to the Roots pump, but may be any other pump that has a rotor and is coated with a resin. .

In the Roots pump, the rotor 10 is supported by each support shaft 10', and a gear (not shown) is attached to one end of each of the support shafts JO'.
They are designed to be able to rotate synchronously in either direction or in opposite directions. An electromagnetic clutch 11 is attached to the opposite end of the support layer 0' of one rotor 10, and the electromagnetic clutch 11 is connected to the engine crankshaft via a belt 12 and a crank pulley 13.
A bypass passage 16 is connected to the intake passage 2 by bypassing the throttle valve 6 and the supercharger 7, and the idle speed control valve 1 is controlled by the control device [15] through the intake passage 2.
7 is placed. The control unit J5 also controls the idle speed control valve 17 and the fuel phase injection valve 9. These controls can be performed by known methods and will not be described in further detail here. What is important is that the supercharger 7 is subjected to changes in the surrounding environment with rapid temperature changes, and its compression action leads to even higher temperatures.

Applying a resin coating to the outer circumferential surface of the rotor of such a mechanical turbocharger increases pump efficiency, and even when foreign objects are caught, such foreign objects are buried in the handle oil layer and the rotor surface shape is changed. It is known that damage can be prevented. However, as mentioned above, such a resin has good heat resistance and is likely to peel off from the rotor base material, so it is no wonder.

Such abrasion occurs at the inward curvature indicated by arrow X in FIG. 10-ta 1 in figure 2 and figure 3
0 has a central hole 20 for fitting into a support shaft and a hollow hole 2J for IQ=quantization.

Such holes 20, 21 and a predetermined external shaft shape (
An aluminum rotor base 22 with a thickness of 1 fa is prepared, and its outer circumferential surface and both end surfaces are successively coated with resin as shown by ridges 23 and 24.

In the image 9M1ir11, the base 22 is slightly exposed around the central hole 20, and the Mi fat has entered the hollow hole 21 up to its inner diameter surface.

This Sen1] F+ is both tetrafluoroethylene and Eblen (a)
An example of the chemical formula is shown below.

The thickness of the resin coated on the rotor of a mechanical supercharger is 0.
It is preferably in the range of 2 mw to 1.00 m,
Most preferably about 0.5 mm. FIG. 4 shows the results of a thermal cycle test when the thickness was 0.511 Im. This was varied from -40° C. to +120° C., no cycle was repeated 2, and the number of cooling/heating cycles until peeling was observed was used as an argument. The base of the resin is A is nylon 12, B is
is tetrafluoroethylene, and C is a tetrafluoroethylene-ethylene polymer. In the results shown in Figure 4, B and C are target targets.
It was found that nylon A could not be used as a rotor for a supercharging plate.

In addition, in the case of tetrafluoroethylene (B), a special base treatment was performed prior to resin coating, and without such base treatment, the tetrafluoroethylene-ethylene copolymer (C) It is not possible to obtain results equivalent to . This type of surface treatment was developed by Nagisa, who initially considered tetrafluoroethylene as the most likely candidate, and continued his research on it. This resulted in higher manufacturing prices. By using the tetrafluoroethylene-ethylene copolymer of C, it is possible to reach the target number of cycles without the need for such an undercoat, and it is possible to achieve the target cycle number No. 1, which is equivalent in performance but considerably disadvantageous in terms of price. To,
When the p'+4 fluorinated ethylene-ethylene copolymer is subjected to shot blasting or alumite treatment after shot blasting, it becomes even more difficult to peel off. Even if such a treatment is performed, it is possible to produce a rotor that is cheaper than the lower J411 treatment using tetrafluoroethylene. Why does the tetrafluorinated ethylene-ethylene copolymer have such excellent releasability? Because it has a relatively low viscosity, it is easy to physically handle the rotor base material, and the hydrogen atoms are low. This is thought to be due to the fact that it is easy to chemically bond with surface atoms (especially oxygen) of the substrate1.Also, electrostatic coating method, induction coating method, and fluidized coating method are used for coating the tetrafluoroethylene-ethylene symbiotic compound. Shakuhofu is available.

As described in detail, according to the present invention, it is possible to obtain a resin coating that is inexpensive and difficult to peel off, and it is possible to improve the performance and durability of a mechanical supercharger.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of an internal combustion engine equipped with a mechanical supercharger, Figure 2
The figure is an enlarged end view of the rotor shown in FIG. 1, FIG. 3 is a sectional view taken along the heel 1n-1 in FIG. 2, and FIG. 4 is a graph showing the results of a cold rifle test. ■... Engine body, 2... Intake passage, 7... Supercharger, 10... Rotor, 22... Rotor base material, 23.2
4...Resin. Patent Applicant Toyota Motor Corporation Nippondenso Co., Ltd. Patent Application Representative Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Kyosuke Tsuchiyama Patent Attorney Akira Yamaguchi Patent Attorney Masaya Nishiyama Figure 1 5 (Figure 4 1 A B Cf type 2nd I Figure 3, 2

Claims (1)

[Claims] A mechanical supercharger installed in the leisure system of an internal combustion engine, characterized in that the outer peripheral surface of the rotor of the mechanical supercharger is coated with a tetrafluoroethylene-ethylene copolymer resin.