JP2006194106A - Valve device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce friction caused in a slide contact part of a valve shaft and a seal bearing by applying a hard carbon material and grease to the slide contact part of the valve shaft and the seal bearing. <P>SOLUTION: This valve device is provided in an intake path of the engine, and the valve shaft 5 provided with a valve 4 and a lip seal 7 for holding the valve shaft 5 turnably slide and come into contact mutually through ester oil and/or grease using ester oil as base oil. A hard carbon thin film having hydrogen content of 20 atom% or less is formed on a slide contact face of at least either of the valve shaft 5 and the lip seal 7. By using the hard carbon thin film and grease in the slide contact part of the valve shaft 5 and the lip seal 7 in this way, friction can be greatly reduced while maintaining sealing property of the slide contact part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a butterfly type valve device used for a variable intake control valve, a swirl control valve, etc., for example, in an automobile engine.

  Valve devices such as engine variable intake control valves and swirl control valves use butterfly valves that open and close the intake path. These valve devices have a structure in which a plate-like valve is attached to a valve shaft, the valve shaft is rotatably held by a seal bearing, and the valve is rotated together with the valve shaft using a negative pressure type or motor type actuator as a drive source. It has become.

  Here, in the above valve device, the valve shaft and the seal bearing are in sliding contact. Especially in the variable intake control valve and the swirl control valve, the air moment due to the intake air, the vibration of the engine, the temperature environment, etc. Because of this, the friction at the sliding contact portion increases, so an actuator that can sufficiently cope with the load has been used.

By the way, in recent years, environmental problems on a global scale such as global warming and destruction of the ozone layer have been greatly highlighted, and in particular, CO ₂ reduction, which is said to have a major impact on global warming, has been There is great interest in how to determine the regulation value. Regarding this CO ₂ reduction, it is one of the major issues to reduce the fuel consumption of automobiles, and in automobiles having various sliding mechanisms, a sliding mechanism with a low friction coefficient is realized to reduce fuel consumption. In addition, the sliding material and the lubricating oil play a large role.

  In automobiles, the role of sliding materials is to exhibit excellent wear resistance and low coefficient of friction for parts with severe frictional wear environment. Recently, various hard thin film materials have been applied. Yes. In general, hard carbon materials, particularly DLC (diamond-like carbon) materials, have a friction coefficient in the air or in the absence of lubricating oil, and wear-resistant hard coating materials such as titanium oxide (TiN) and chromium nitride (CrN). Therefore, it is expected as a low friction sliding material.

  Furthermore, as fuel saving measures in lubricating oil, (1) reduction of viscosity resistance in fluid lubrication area by lowering viscosity, (2) mixing and boundary lubrication area by blending optimum friction modifier and various additives Friction loss reduction is proposed, and as a friction modifier, many studies have been made mainly on organic molybdenum compounds such as molybdenum dithiocarbamate (MoDTC) and molybdenum dithiophosphate (MoDTP). On the sliding surface made of the steel material, a lubricating oil blended with an organomolybdenum compound exhibiting an excellent low friction coefficient at the beginning of use was applied, and the effect was improved.

For example, Non-Patent Documents 1 and 2 have been reported on the friction characteristics of such DLC materials and the performance of organic molybdenum compounds as friction modifiers.
Kano et al., Proceedings of Japan Society of Tribology, May 1999, p. 11-12 Kano et al., World Tribology Congress 2001.9, Vienna, Proceeding p. 342

  However, in the valve device as described above, especially in a variable intake control valve and a swirl control valve, when a large actuator is used so as to be able to cope with friction generated in the sliding contact portion between the valve shaft and the seal bearing, As a result, there is a problem in that it is disadvantageous in terms of response speed, power consumption, manufacturing cost, layout in the engine room, and the like.

  The reason why a large actuator is required as described above is due to the friction generated in the sliding contact portion between the valve shaft and the seal bearing. Therefore, in order to reduce the friction in this sliding contact portion. Improvement was desired.

  Further, Non-Patent Document 1 reports that a general DLC material that is excellent in low friction in air does not necessarily have a large friction reducing effect in the presence of lubricating oil. According to No. 2, it has been found that even if a lubricating oil composition containing an organomolybdenum compound is applied to such a sliding material, the friction reducing effect may not be sufficiently exhibited.

  Further, in engine valve devices that are exposed to relatively high temperatures and high pressures, grease is used as a lubricant instead of lubricating oil. However, the use of such grease with a hard carbon material such as DLC is still not available. Not considered.

  The present invention has been made in view of the above-described conventional situation, and in a valve device provided in an intake passage of an engine or the like, a hard carbon material and grease are employed in a sliding contact portion between a valve shaft and a seal bearing. An object of the present invention is to provide an engine valve device capable of realizing a significant reduction in friction while maintaining sealing performance.

  An engine valve device according to the present invention is a valve device provided in an intake passage or the like of an engine, and a valve shaft provided with a valve and a seal bearing that rotatably holds the valve shaft include ester oil and / or ether. It is in sliding contact via grease based on oil, a hard carbon thin film is formed on at least one sliding contact surface of the valve shaft and the seal bearing, and the hydrogen content of the hard carbon thin film is 20 It is characterized in that it is not more than atomic%, and this realizes a significant reduction in friction while maintaining the sealing performance at the sliding contact portion between the valve shaft and the seal bearing.

  Moreover, the suitable form of the valve apparatus of the engine which concerns on this invention is characterized by the said grease using the metal soap or the urea type compound containing calcium or lithium as a thickener.

  The engine valve device of the present invention employs a hard carbon material such as DLC and a specific grease for the sliding contact portion between the valve shaft and the seal bearing, thereby sufficiently maintaining the sealing performance of the sliding contact portion. Friction can be greatly reduced.

  As a result, in valve devices such as variable intake control valves and swirl control valves, it is possible to reduce the size of the drive actuator and simplify the structure along with the reduction of friction. As the speed increases, it is possible to realize an improvement in response speed, power saving, improvement in fuel efficiency and cost reduction accompanying power saving, and further contribute to improvement in engine performance.

  In addition, as the friction at the sliding contact portion between the valve shaft and the seal bearing is reduced, it becomes possible to set a higher tightening force of the seal bearing against the valve shaft, which is unique to the engine, that is, under high frequency vibration and high pressure pulsation. Even in this environment, it is possible to further improve the sealing performance of the sliding contact portion.

  Hereinafter, the present invention will be described in more detail. In this specification, “%” represents a mass percentage unless otherwise specified.

  FIG. 1 is a diagram illustrating a variable intake control valve (tumble control valve) as an engine valve device. This valve is a butterfly type valve, and is provided in each intake passage corresponding to each cylinder in the intake manifold 1 to increase the length of the effective intake port by closing at low and medium speeds. By opening at high speed, the length of the effective intake port is reduced to improve the torque in each rotation region.

  The variable intake control valve includes a plate-like valve 4 that opens and closes a port 3 formed on the flange 2 of the intake manifold 1 and a valve shaft 5 that passes through the intake manifold 1 so as to pass through each port 3. Each valve 4 is screwed to the valve shaft 5. The valve shaft 5 is made of various metal materials typified by iron-based alloys such as steel and non-ferrous metal alloys such as aluminum alloys, and can be rotated by bearing portions 6 provided on both sides of each valve 4 in the intake manifold 1. Both ends are rotatably held by the lip seal 7.

  The lip seal 7 corresponds to a seal bearing that rotatably holds the valve shaft 5, and as shown in FIG. 3A, an annular portion 7 a that fits the flange 2, and an annular portion It integrally has a pair of fins 7b protruding inside 7a. As the seal bearing, as shown in FIG. 3B, a seal ring (X-ring) 57 having an X-shaped cross section can be adopted, and a bearing having another shape is naturally applicable. Is possible.

  For these seal bearings (lip seal 7, seal ring 57), rubber materials (H-NBR, NBR, fluorine, etc.), metal materials, and resin materials are used depending on the peripheral structure and required seal performance. A material etc. can be used.

  A rotating lever 8 is connected to one end of the valve shaft 5, and a connecting pin 9 is provided on the rotating lever 8 at a position offset from the valve shaft 5. The output rod 10a of the negative pressure actuator 10 is connected. Thus, when the variable intake control valve drives the output rod 10a of the negative pressure actuator 10 to advance and retreat, the valve shaft 5 reciprocates through the rotation lever 8, and at the same time, the valve 4 reciprocates to rotate the port. 3 is opened and closed.

  At this time, in the variable intake control valve, the valve shaft 5 including the valve 4 and the lip seal 7 that rotatably holds the valve shaft 5 are in sliding contact with each other while maintaining the sealing performance. In view of this, the variable intake control valve particularly forms a hard carbon thin film having a hydrogen content of 20 atomic% or less on at least one sliding contact surface between the valve shaft 5 and the lip seal 7 and the valve shaft 5 And a lip seal 7 with a grease based on ester oil and / or ether oil as a base oil, which greatly reduces friction at the sliding contact portion while maintaining sufficient sealing performance. ing. In terms of ease of film formation, it is desirable to form a hard carbon thin film on the valve shaft 5.

  In this way, if the friction at the sliding contact portion between the valve shaft 5 and the lip seal 7 is reduced, a small negative pressure actuator can be obtained even if it is affected by the air moment due to the intake air, the vibration of the engine and the temperature environment. 10 can sufficiently drive the valve 4 and does not require an amplifying mechanism such as a crank mechanism for increasing torque, which increases the degree of freedom in layout of the equipment in the engine room and increases the response speed. Improvement, power saving, fuel efficiency improvement and cost reduction associated with power saving can be realized.

  FIG. 2 is a diagram illustrating a swirl control valve as an engine valve device. This valve is a butterfly valve, and is provided in each intake passage corresponding to each cylinder in the intake manifold 11, and in particular, the intake passages 13a and 13b branched into two for each cylinder. One of the intake passages 13a is opened and closed.

  The swirl control valve is configured to pass through each intake passage 3a with respect to the intake manifold 11 and a plate-like valve 14 that opens and closes the intake passage 3a in the intake manifold 11 in the same manner as the variable intake control valve. A valve shaft 15 is provided, and each valve 14 is screwed to the valve shaft 15. In the intake manifold 11, the valve shaft 15 is rotatably held by bearings 16 on both sides of each valve 14, and both ends are rotatable by a lip seal 17 (or seal ring 57) which is a seal bearing. It is held in.

  A rotating lever 18 is connected to one end of the valve shaft 15, and a connecting pin 19 is provided at a position offset from the valve shaft 15. The output rod 20a of the electronic control motor type actuator 20 is connected to this. Thereby, when the output rod 20a of the electronic control motor type actuator 20 is driven forward and backward, the swirl control valve reciprocates the valve shaft 15 via the rotation lever 18, and simultaneously the valve 14 reciprocates. The intake passage 3a is opened and closed.

  At this time, in the swirl control valve, the valve shaft 13 provided with the valve 14 and the lip seal 17 that rotatably holds the valve shaft 13 are in sliding contact with each other while maintaining sealing performance. Therefore, the swirl control valve forms a hard carbon thin film having a hydrogen content of 20 atomic% or less on at least one sliding contact surface between the valve shaft 15 and the lip seal 17, and the valve shaft 15 and the lip seal. In this state, grease having ester oil and / or ether oil as a base oil is interposed between them and the friction at the sliding contact portion is greatly reduced while maintaining sufficient sealing performance.

  In this way, if the friction at the sliding contact portion is reduced, the valve 14 can be sufficiently connected even with the small electronically controlled motor type actuator 20 even if it is affected by the air moment due to the intake air, the vibration of the engine and the low temperature environment. As a result, the degree of freedom of the layout of the equipment in the engine room can be increased. In addition, the response speed can be improved, the power can be saved, the fuel consumption can be improved, and the cost can be reduced.

  Here, in the valve device of the engine shown in FIGS. 1 and 2, the environment between the valve shaft and the seal bearing (lip seal or seal ring) is subjected to high frequency vibration and pressure pulsation (low pressure side and high pressure side). . Table 1 shows examples of engine types, high-frequency vibrations, and pressure pulsations.

  That is, between the valve shaft and the seal bearing is a part that requires sealing performance and sliding contact operation in the above environment. If a large amount of air leakage occurs, the air flows into the engine cylinder and becomes excessive. Therefore, it is necessary to reduce friction while ensuring sufficient sealing performance.

  Therefore, in the present invention, the valve shaft and the seal bearing are in sliding contact via grease based on ester oil and / or ether oil, and at least one sliding contact surface of the valve shaft and seal bearing is used. In addition, by forming a hard carbon thin film having a hydrogen content of 20 atomic% or less, friction reduction can be achieved while sufficiently ensuring the sealing performance at the sliding contact portion between the valve shaft and the seal bearing.

  Examples of the hard carbon thin film include a crystalline or amorphous thin film containing carbon, in particular, a diamond thin film and a DLC thin film, such as various PVD methods, specifically, arc ion plating. A DLC thin film (diamond-like carbon thin film) formed by a method is desirable.

The DLC thin film is composed of a so-called DLC material, and this DLC material is an amorphous material mainly composed of carbon atoms, and the bonding form of the carbon atoms is a diamond structure (SP ³ Bond) and graphite bond (SP ² bond).

  Specifically, aC (amorphous carbon) consisting only of carbon atoms, aC: H (hydrogen amorphous carbon) containing hydrogen, and some metal atoms such as titanium (Ti) and molybdenum (Mo). In the present invention, the lower the hydrogen content, the more preferable. The hydrogen content is 20 atomic% or less, preferably 10 atomic% or less, particularly 0.5 atomic% or less, An aC-based (amorphous carbon-based) material that does not contain hydrogen can be preferably used.

  The film thickness of the hard carbon thin film is affected by the type and required performance of the target valve shaft and seal bearing, the type of material constituting the valve shaft and seal bearing, the surface roughness of the sliding part, etc. In the case of a thin film, for example, the thickness is preferably about 0.3 to 2.0 μm.

  In addition, the surface roughness of the base material before the formation of the hard carbon thin film is also the type and required performance of the target valve shaft and seal bearing, the type of base material constituting the valve shaft and seal bearing, and the surface roughness of the sliding part. However, when applying the DLC thin film to the valve device of the engine, if the base material is steel, the surface roughness before coating the hard carbon thin film may be 0.1 μm or less in Ra. preferable.

  Furthermore, when the base material is an aluminum alloy, Ra is preferably 0.02 μm or less, and when rubber or plastic is used, Ra is preferably 0.1 μm or less.

  Furthermore, the hard carbon thin film is usually covered on the entire sliding surface of at least one of the valve shaft and the seal bearing, but may be covered on a part of the sliding surface.

  Next, as described above, the grease used is based on ester oil and / or ether oil, but this base oil is not limited to those containing only ester oil or ether oil. However, other natural oils and synthetic oils may be included. Examples of other base oil components include mineral oil, silicone oil, fluorocarbon oil, and the like.

  The ester oil is not particularly limited as long as it can be used as a component of a lubricant, but it is not limited whether it is a natural oil or a synthetic oil. Specific examples include ditridecyl glutarate, dioctyl adipate, diisodecyl adipate, ditrile. Examples include decyl adipate, dioctyl sebacate, trimethylolpropane caprylate, trimethylolpropane pelargonate, trimethylolpropane isostearinate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate, and the like. Rate is preferably used.

  It does not matter whether the ether oil is a natural oil or a synthetic oil as long as it can be used as a component of a lubricant. Specific examples include polyoxyalkylene glycol, dialkyl diphenyl ether and polyphenyl ether, and dialkyl diphenyl ether is preferred.

The base oil containing the above components typically has a base oil viscosity at 100 ° C. of about ^{2 to} 100 mm ² / s, preferably about ² to 40 mm ² / s, more preferably about 10 to 20 mm ² / s. It becomes.

In addition, when kinematic viscosity is less than 2 mm < ² > / s, since sufficient abrasion resistance is not acquired and an evaporation characteristic may be inferior, it is unpreferable. On the other hand, if the kinematic viscosity exceeds 100 mm ² / s, it is difficult to exhibit low friction performance, and low temperature performance may be deteriorated, which is not preferable.

  The viscosity index of such base oil is typically 100 or more, preferably 120 or more, and more preferably 140 or more. By selecting a base oil having a high viscosity index, it is possible to obtain a composition that not only has excellent low-temperature viscosity characteristics, but also has low oil consumption and excellent low-temperature viscosity characteristics, fuel saving performance, and friction reduction effect.

  On the other hand, examples of the thickener contained in the grease include various metal soap-based materials and non-metal soap-based materials. Examples of the metal soap material include sodium, calcium, aluminum, lithium, barium, copper and lead salts of higher fatty acids, and complex salts of higher fatty acids with lower fatty acids or dibasic acids. As these metal soap materials, calcium stearate, lithium hydroxystearate, lithium stearate, sodium stearate and aluminum stearate are suitable.

  Non-metallic soap materials include inorganic materials (organic thickeners) such as silica gel and bentonite, and organic materials (inorganic thickeners) such as copper phthalocyanine, allylurea, imide derivatives and indanthrene blue. be able to. As these non-metallic soap thickeners, urea compounds such as diurea, sodium terephthalamate and PTFE are suitable.

  In the above-described grease, it is possible to add an antioxidant, a detergent, an antiwear agent, a solid lubricant and the like to the base oil and the thickener.

  The antioxidant is not particularly limited, and examples thereof include those conventionally used in greases. Examples thereof include amine compounds, phenols, sulfur compounds, and carbamates.

  In addition, the detergent is not particularly limited, and examples thereof include those conventionally used in greases. Examples thereof include sulfonates, phenates, sacylates, and amine compounds.

  The antiwear agent is not particularly limited, and examples thereof include those conventionally used in grease. Examples thereof include phosphate esters, zinc dialkyldithiophosphates, sulfur compounds, and chlorides.

  Furthermore, the solid lubricant is not particularly limited, and examples thereof include those conventionally used in grease.

  The properties of the above grease itself are affected by the purpose and operating conditions of the sliding mechanism used, but typically the consistency is about 265 to 295 and the dropping point is about 100 to 300 ° C. Is preferred.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

(Examples 1-4)
As shown in FIG. 4, a cylinder-shaped test piece 100 and a disk-shaped test piece 200 were made of SUJ2 steel in order to measure the friction coefficient using a cylinder-on-disk single-piece reciprocating friction tester. These cylindrical test piece 100 and disc-shaped test piece 200 correspond to a seal bearing and a valve shaft.

Next, the surface of the upper sliding surface of the disk-shaped test piece 200 is subjected to a PVD arc ion ion plating method with a hydrogen atom amount of 0.5 atomic% or less, a Knoop hardness Hk = 2170 kg / mm ² , and a surface roughness Ry = 0. A DLC thin film having a thickness of 03 μm and a thickness of 0.5 μm was formed, and the sliding mechanism of this example using the cylindrical test piece 100 and the disk-shaped test piece 200 as sliding members was manufactured.

  Next, about 0.3 g of the grease shown in Table 2 was applied between the cylindrical specimen 100 and the disk specimen 200, and a friction test was performed under the following conditions to measure the friction coefficient. Table 2 shows the components of the specimen material and grease. Further, the coefficient of friction of the sliding mechanism of each example after 10 minutes of the test was graphed and shown in FIG.

[Friction test conditions]
・ Test equipment: Cylinder-on-disk single-piece reciprocating friction tester ・ Sliding side test piece; φ15 × 22 mm cylindrical test piece ・ Math side test piece; φ24 × 7.9 mm disc-like test piece ・ Load; (Pressing load of one piece)
・ Amplitude: 1.5mm
・ Frequency: 50Hz
Test temperature: 80 ° C
・ Measurement time: 10 min

(Comparative Examples 1-6)
Except that no DLC thin film was formed on the disk-shaped test piece 200, the same operation as in Examples 1 to 4 was repeated, and the friction coefficient was measured. The obtained results are shown in FIG.

As an embodiment of an engine valve device according to the present invention, an exploded perspective view (a) illustrating a variable intake control valve, a front view (b) of a flange portion of an intake manifold, and a side view (c) of a negative pressure actuator portion ). As other embodiments of the valve device of the engine according to the present invention, a sectional view for explaining a swirl control valve (a), a valve front view in an open state (b), a valve front view in a closed state (c), and It is side part sectional drawing (d). It is a figure which shows a valve shaft and a seal bearing, Comprising: It is sectional drawing (a) which shows the case where a lip seal is used as a seal bearing, and is sectional drawing (b) which shows the case where a seal ring is used as a seal bearing. FIG. 2 is a perspective view schematically illustrating a cylinder-on-disk single-piece reciprocating friction tester. It is a graph which shows a friction coefficient.

Explanation of symbols

5 15 Valve shaft 7 17 Lip seal (seal bearing)
57 Seal ring (seal bearing)

Claims (7)

  A valve device provided in an intake path or the like of an engine, in which a valve shaft provided with a valve and a seal bearing that rotatably holds the valve shaft are interposed with grease using ester oil and / or ether oil as a base oil. The hard carbon thin film is formed on at least one of the sliding contact surfaces of the valve shaft and the seal bearing, and the hydrogen content of the hard carbon thin film is 20 atomic% or less. The engine valve device.   2. The valve device for an engine according to claim 1, wherein the hydrogen content of the hard carbon thin film is 10 atomic% or less.   2. The valve device for an engine according to claim 1, wherein the hydrogen content of the hard carbon thin film is 0.5 atomic% or less.   The engine according to any one of claims 1 to 3, wherein the surface roughness of the substrate of the member on which the hard carbon film is formed is 0.1 µm or less in Ra before coating with the hard carbon thin film. Valve device.   The engine valve device according to any one of claims 1 to 4, wherein the grease comprises a metal soap containing calcium or lithium or a urea compound as a thickener.   6. The engine valve device according to claim 1, wherein the hard carbon thin film has a thickness of 0.3 to 2.0 [mu] m.   7. The valve device for an engine according to claim 1, wherein the hard carbon thin film is a DLC thin film formed by a PVD method.

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