JPS63147921A - Nozzle vane driver for variable displacement turbosupercharger - Google Patents

Abstract

PURPOSE:To smooth rotation of a slide joint making a pin a fulcrum, by forming a chromizing oxidation-resistant layer on a contact surface between the slide joint and the pin. CONSTITUTION:A link plate 22, a slide joint 23 and a pin 25 is made up of steel containing any one of Al, Cr, Mo and Ti or more than two of them. The whole link plate 22 or at least a part of a groove 26 showing a U-shaped form of the link plate 22 is applied with a process of nitriding, whereby a nitriding layer is formed thereon. Chromizing is applied on an outer circumferential part of the pin 25, and a chromizing oxidation-resistant layer is formed thereon. Also, chromizing treatment is applied onto an inner circumferential surface where the slide joint 23 and the pin 25 are made contact with each other, thus the chromizing oxidation-resistant layer is formed. Nitriding is applied onto an outer circumferential surface to be contacted with the groove 26 of the link plate 22 of the slide joint 23, and the nitriding layer is fromed thereon as well.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a variable displacement turbocharger for vehicles in which the link plates, slide joints, and pins for controlling the nozzle vanes are improved in material. The present invention relates to a nozzle vane drive device.

[Prior Art] Generally, it is known that a variable displacement turbocharger uses a link mechanism to variably control the blade angles of a plurality of nozzle vanes provided in a turpin housing along its nozzle opening.

Conventionally, this variable capacity turbocharger 1 has been constructed as shown in FIGS. 6 to 8.

As shown in the figure, a plurality of nozzle vanes 4 are provided within the turpin housing 2 along the circumference of the nozzle opening 3 at appropriate intervals. Each nozzle vane 4 is rotatably supported by a rotating shaft 5 passing through the turpin housing 2, so that its blade angle can be arbitrarily varied. This nozzle vane 4 was controlled by a nozzle vane drive device 6 as described below. Each rotary shaft 5 is provided with a link plate 7 fixed at one end to the shaft end outside the turpin housing 2 for rotating the rotary shaft 5 to variably control the blade angle of the nozzle vane 4.
The other end of these link plates 7 is the turpin housing 2
are arranged radially outward in the radial direction. A drive ring 8 is provided at the other end of each link plate 7 to engage therewith and uniformly rotate each link plate 7 around the rotation axis 5. This drive ring 8 is configured to be rotated in the circumferential direction by a drive means 9 such as a drive lever. The other end of the link plate 7 is formed into a substantially U-shape and is provided with a groove 10 for engaging the drive ring 8 therein.

On the other hand, the drive ring 8 is provided with a pin 11 which is implanted therein and engages with the groove 1o, and this pin 11 has a rectangular parallelepiped-shaped slide joint 1 rotatably fitted therein.
2 is provided. The link plate 7 and the drive ring 8 are engaged with each other via the slide joint 12 and the pin 11, and the side surface of the slide joint 12 is slidable into the groove 10 of the link plate 7.

[Problem to be Solved by the Invention 1] By the way, although the mechanism and advantages of conventional variable displacement turbocharging [1] are understood, it has not been mass-produced especially for vehicles, and the reasons for this are unclear. However, there were the following durability problems.

The material of the slide joint 12 and pin 11 that make up the nozzle vane drive device 6 is oxidized by the exhaust gas, and the slide joint 12, which rotates around the pin 11 as a fulcrum due to volumetric expansion, sticks to the pin 11 and malfunctions. There was a problem with getting there.

Further, due to mechanical vibrations and nozzle pulsations, the groove 10 of the link plate 7 constituting the nozzle vane drive device 6 comes into contact with the side surface of the slide joint 12, causing fretting wear and problems.

In view of the above-mentioned problems, the object of the present invention is to develop a nozzle vane drive device having oxidation resistance and fretting wear resistance, thereby achieving practical use of a variable displacement turbo supercharger for vehicles. It is.

[Means for Solving the Problems] In order to solve the problems in the prior art, the present invention provides a link plate, a slide joint, and a pin for controlling a nozzle vane rotatably disposed on the outer periphery of a turbine rotor. , Cr, Mo.

Molded with a steel material containing one or more of Ti,
The inner circumferential surface of the slide joint and the pins in contact with the inner circumferential surface are chromized to form a chromized oxidation-resistant layer, and the outer circumferential surface of the slide joint and the link plates in contact with the outer circumferential surface are nitrided. A nitride layer is formed by processing.

[Function] With the structure as described above, the inner circumferential surface of the slide joint and the pins in contact with the inner circumferential surface are subjected to chromizing treatment to form a chromized oxidation-resistant layer, thereby preventing oxidation of these materials. Since volumetric expansion due to Aj! is prevented, smooth rotation of the slide joint using the pin as a fulcrum is maintained, and the link plate, slide joint, and pin Aj! , Cr, MO, and Ti, and the outer circumferential surface of the slide joint and the link plate in contact with this outer circumferential surface are subjected to nitriding treatment to form a nitrided layer. By this, Aβ
, Cr, Mo, and Ti each promote the hardening of the nitride layer to improve the HV
It has a hardness of over 1000 and prevents fretting wear caused by contact between the slide joint and link plate.

Examples] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the present invention provides a nozzle vane 2
It is characterized by a link plate 22, a slide joint 23, and a pin 25 integrally provided on a drive ring 24, which constitute a nozzle vane drive device @21 that controls the blade angle of the nozzle vane. The shape and structure of these link plates 22, slide joints 23, and pins 25 are formed in the same manner as in the conventional art. These link plates 22, slide joints 23, and pins 25 are Aj!
, Cr, Mo, Ti (D) is molded from steel containing two or more. In this example, +8
It is molded from SU3304 whose main elemental component is Or-8Ni. The entire link plate 22 or at least the U-shaped groove 2 of the link plate 22
The portion 6 is subjected to nitriding treatment to form a nitrided layer. This nitriding treatment is performed by an ion nitriding method in this embodiment. Further, the outer circumferential portion of the pin 25 is subjected to chromizing treatment to form a chromized oxidation-resistant layer. Furthermore, the inner circumferential surface of the slide joint 23 that comes into contact with the pin 25 is chromized to form a chromized oxidation-resistant layer. The groove 2 of the link plate 22 of this slide joint 23
The outer peripheral surface in contact with 6 is subjected to nitriding treatment to form a nitrided layer. This nitriding treatment is performed by the ion nitriding method as described above. In this embodiment, the entire slide joint 23 is chromized to form an O-mized oxidation-resistant layer over the entire surface, and then the chromized oxidation-resistant layer on the outer peripheral surface that contacts the groove 26 of the link plate 22 is polished. After that, the outer peripheral portion thereof is subjected to nitriding treatment using an ion nitriding method to form a nitrided layer.

Next, the operation of the above embodiment will be described based on experimental data.

As mentioned above, the problems in the prior art can be solved by establishing oxidation resistance and high temperature fretting wear resistance.

Therefore, in order to select a material that satisfies these two conditions, we first selected the materials shown in Table 1 below as candidate materials for the oxidation-resistant layer, and conducted tests to examine their high-temperature fretting properties.

Table 1 The test machine used was a device as shown in Figure 3.

As shown in the figure, the upper part of this testing machine 27 is a fixed shaft 28, and the lower part is a movable shaft 29. A test piece 30 is attached between the fixed shaft 28 and the movable shaft 29. This test piece 30 consists of a plate spring member 31 provided on the fixed shaft 28 side and a plate member 3 provided on the movable shaft 29 side.
It consists of 2. Then, O to 5k (
By applying a load of 1 and moving up and down for 30 cycles x 4 hours, 7 retching wear is prevented from occurring due to the relationship between displacement and load of the leaf spring member 31.

This tester 27 is inserted into a heating furnace 33 in order to examine high-temperature fretting wear characteristics.

The above test piece 30 was formed from the same materials for materials A to E shown in Table 1 and comparative materials, and
Tests were conducted at 0°C.

As a result, as shown in Figure 4, for the materials A-E,
Although there was no problem with oxidation resistance, the high temperature fretting resistance was not superior to a comparative material made of 5IJS304 subjected to ion nitriding treatment, and it was considered to be of no practical use.

Next, regarding 7 retching properties, there are very few studies that have conducted tests at high temperatures, so the materials shown in Table 2 below are generally made of copper alloys, which are said to have relatively good properties against fretting wear. A test was conducted to investigate the high-temperature fretting properties of these materials.

Table 2 A testing machine 27 similar to that shown in FIG. Tests were conducted at 450°C.

As a result, as shown in Figure 5, it was found that oxidation was not applicable to the materials F and G, and the material H-L was more abrasive than the comparative material, which was SUS 304 subjected to ion nitriding. were considered to be inapplicable.

From the above two test results, it was considered that it would be extremely difficult to find a practical material that has both oxidation resistance and high temperature fretting wear resistance.

When the above test results were summarized, the following facts were found. This is because mechanical vibrations and nozzle pulsations accelerate vibrations in the link system that constitutes the nozzle vane driving device 21, causing fretting wear.

However, this fretting wear is caused by the link plate 2
The contact surface between 2 and slide joint 23 is the most severe,
It was found that the wear of the contact surface between the slide joint 23 and the pin 25 was not so great. Furthermore, under severe conditions due to heat load, the slide joint 23 and pin 25 oxidize and expand in volume, causing a problem of sticking between the slide joint 23 and the pin 25. This sticking phenomenon is caused by the link plate 22 and the slide. joint 2
It was found that this does not occur between 3 and 3.

Based on the above facts, separate countermeasures should be taken for oxidation resistance by focusing on the contact surface between the slide joint 23 and the pin 25, and for fretting wear by focusing on the contact surface between the link plate 22 and the slide joint 23. And so. From this point of view, there are methods shown for materials A to D above as surface treatments that provide oxidation resistance.
Regarding materials B and B, it is extremely difficult to treat the inner circumferential surface of the slide joint 23 and it is not practical. And vice versa,
Ion nitriding is the most suitable treatment for the outer circumferential surface of the slide joint 23 where ruching wear is a problem.

In order to confirm this, we considered the combinations of materials shown in Table 3 below and conducted tests on oxidation resistance and fretting wear resistance.

Table 3 In the above embodiment, after the slide joint 23 is chromized to form a chromized oxidation-resistant layer on the entire slide joint 23, the chromized oxidation-resistant layer on the outer peripheral surface that contacts the groove 26 of the link plate 22 is polished. and then remove it,
A nitrided layer was formed on the outer periphery by nitriding using an ion nitriding method, and a test on an actual machine proved that this method had good results. On the other hand, an attempt was made to mold the slide joint 23 using 31J 3304 material and perform ion nitriding treatment only on its outer peripheral surface. However, when formed in this way, it is necessary to perform ion nitriding prevention only on the inner peripheral surface.
This not only requires a long pretreatment time before processing, which is not good for productivity, but also, according to actual machine tests, the contact surface between the slide joint 23 and the pin 25 was severely worn out, making it impractical. .

Further, the nitriding treatment may be performed by applying a gas nitriding method, in which the link plate 22, slide joint 23, and pin 25 are formed from a steel material containing one or more of Af, Or, Mo, and 7i. As a result, the nitriding hardness is improved and shows a high value of HV 1000 or more.

[Effects of the Invention] In summary, the present invention exhibits the following excellent effects.

(1) Since a chromized oxidation-resistant layer is formed on the contact surface between the slide joint and the pin, the rotation of the slide joint around the pin as a fulcrum can be maintained smoothly without volume expansion due to oxidation. .

Q) The link plate, slide joint, and pin are formed from a steel material containing one or more of AN, Cr, Mo, and Ti, and a nitrided layer is formed on the contact surface between the slide joint and the link plate. Because it was done,
Fretting wear caused by these contacts can be prevented.

(31) From the above results, a nozzle vane drive device with stable material and dimensional accuracy can be obtained, and a variable capacity turbocharger for vehicles can be put into practical use.

[Brief explanation of the drawing]

Figure 1 is a plan view of the main parts showing the link plate, slide joint, and pin, Figure 2 is a view taken along the line ■-■ in Figure 1,
Fig. 3 is a schematic diagram showing the test equipment adopted in the present invention;
Figure 5 is a graph showing the test results, Figure 6 is a front view of the variable displacement turbocharger, Figure 7 is a partial side sectional view of the variable displacement turbocharger, and Figure 8 is the same as Figure 6. It is a view taken along the line ■-■. In the figure, 21 is a nozzle vane drive device, 22 is a link plate, 23 is a slide joint, and 25 is a pin. Patent applicant: Isuzu Motors Co., Ltd. Patent attorney Nobuo Kinutani 77' Figure 1 Figure 2 Figure 4 Figure 5 Figure 7 Figure 6 Procedure number 10 E1 (Voluntary) December 27, 1985 Day 2, Title of the invention: Nozzle vane drive device 3 for variable capacity turbocharger, relationship with the case involving compensation [Applicant (017) Isuzu Automobile Co., Ltd. 4, Agent postal code: 105 Tokyo Atagoyama Attorney Building 5, No. 6-7, Atago 1-chome, Minato-ku, Date of 1liil order Voluntary ('), ? +Ii Positive target drawing 7, details of correction (1) Drawing 5 will be corrected as shown in the attached sheet. 8. Attached documents 1] Record

Claims (1)

[Claims] The link plate, slide joint, and pin that control the nozzle vane are formed from a steel material containing one or more of Al, Cr, Mo, and Ti, and a chromized oxidation-resistant layer is formed on the contact surface between the slide joint and the pin. Also, a nozzle vane drive device for a variable capacity turbocharger, characterized in that a nitrided layer is formed on the contact surface between the slide joint and the link plate.