JPH11115786A - Housing connecting construction for power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pinion housing made of magnesium alloy from corroding by interposing resin material in the condition of approaching the end part of the pinion housing and the end part of a cylinder tube to each other, and fixing the pinion housing and the cylinder tube to each other. SOLUTION: Through holes 1d, 2d are positioned to each other, so as to form a plurality of communicated through holes. Under this condition, by using necessary metal molds, jigs, and the like, resin injection molding is executed on the connecting part of the pinion housing 1 and the cylinder tube 2. A resin member 3 entering the through holes 1d, 2d and solidified is formed. Hereby, the connecting part of the pinion housing 1 and the cylinder tube 2 is perfectly covered with the resin member 3, and not exposed. Consequently, even if it is splashed with electrolytic water solution, the solution does not invade the connecting part of the different metals, and corrosion of the pinion housing made of a magnesium alloy is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing connecting structure for a power steering apparatus.

[0002]

2. Description of the Related Art A power steering apparatus includes a valve housing for accommodating a valve, a pinion housing for accommodating a rack and pinion gear, and a cylinder tube for accommodating a cylinder for receiving a hydraulic pressure from the valve to generate a steering assist force. It is configured. Conventionally, the material of the housing and the tube has been aluminum alloy or iron. However, to reduce the weight, adoption of a metal that is lighter than aluminum alloy or iron is being studied. Specifically, it has been studied to make the pinion housing made of a magnesium alloy. In this case, the pinion housing made of a magnesium alloy and the cylinder tube made of an aluminum alloy or iron are connected to each other, so that dissimilar metals come into contact with each other.

[0003]

Since the pinion housing and the cylinder tube of the power steering device are so-called lower parts of the vehicle, they are exposed to rainwater and splashes from the road surface. Such water contains impurities such as sodium chloride and calcium chloride in most cases, and is an aqueous electrolyte solution. When such an aqueous electrolyte solution is applied to the above-mentioned contact portion between different metals, a local battery is formed there, and magnesium is ionized and melts out, causing corrosion of the pinion housing. In this case, even if a coating material (phenolic resin) is applied to the outer peripheral surface side of the contact portion to prevent corrosion of the electrolyte by preventing intrusion of the aqueous electrolyte solution, the coating film is actually thin and the adhesion is low. The penetration of the aqueous electrolyte solution was unavoidable because of the badness. As described above, when a magnesium alloy is used as the material of the pinion housing for weight reduction, there is a problem that the pinion housing is corroded at a contact portion with the cylinder tube.

[0004] In view of the above-mentioned conventional problems, an object of the present invention is to provide a housing connecting structure of a power steering device capable of preventing corrosion of a pinion housing made of a magnesium alloy.

[0005]

According to the present invention, a rack and pinion gear is housed, a pinion housing made of a magnesium alloy, and a cylinder for generating a steering assist force by receiving hydraulic pressure are housed. In a housing connection structure of a power steering device configured by connecting a cylinder tube, the end portion of the pinion housing and the end portion of the cylinder tube are close to each other, and a resin member is interposed therebetween. A pinion housing and the cylinder tube are fixed to each other (claim 1). In the housing coupling structure as described above, the resin member functions to fix the pinion housing and the cylinder tube to each other while maintaining mutual insulation. Therefore, direct contact between the pinion housing made of a magnesium alloy and the cylinder tube made of an aluminum-based or iron-based metal is prevented.

The present invention also provides a pinion housing made of a magnesium alloy containing a rack and pinion gear, and a cylinder tube made of an aluminum or iron metal, containing a cylinder for generating a steering assist force by receiving hydraulic pressure. In the housing connection structure of the power steering device configured by connecting the end portion of the pinion housing and the end portion of the cylinder tube, the connection portion between the pinion housing and the cylinder tube is connected to each other. At least the outer surface may be covered with a resin member. In the above-described housing connection structure, the pinion housing and the cylinder tube, which are dissimilar metals, come into contact with each other by fitting. However, the outer surface of the connecting portion between the pinion housing and the cylinder tube is covered with the resin member. Therefore, it is possible to prevent the aqueous electrolyte solution from touching the contact portion between the dissimilar metals.

Further, the housing connecting structure (claim 1)
Alternatively, in (2), the resin member may be formed by injection molding, and a plurality of holes for flowing resin may be provided near the end of the pinion housing and near the end of the cylinder tube. Item 3). In this case, the resin flows into the plurality of holes and solidifies,
A strong connection is obtained.

The present invention also relates to a pinion housing containing a rack and pinion gear and containing a magnesium alloy, and a cylinder tube containing a cylinder for receiving a hydraulic pressure and generating a steering assist force and containing an aluminum or iron metal. In the housing connection structure of the power steering device configured by connecting the end portion of the pinion housing and the end portion of the cylinder tube to each other by press-fitting the other end, the joining portion May be applied and cured by applying an epoxy-based paint in such a manner as to cover both members (claim 4). In the housing connection structure as described above, the epoxy paint easily enters the interface between the pinion housing and the cylinder tube, and is excellent in waterproofness and durability.

The present invention also provides a pinion housing containing a rack and pinion gear, made of a magnesium alloy, and a cylinder tube made of an aluminum or iron metal, containing a cylinder for generating a steering assist force by receiving hydraulic pressure. In the housing connection structure of the power steering device, the end of the pinion housing and the end of the cylinder tube are press-fitted into each other with a sealant interposed therebetween. May be mutually insulated and fitted (claim 5). In the above-described housing connection structure, the pinion housing and the cylinder tube, which are dissimilar metals, are fitted to each other, but a sealant (for example, one made of silicone or acrylic resin) is interposed therebetween so that the space (gap) is formed. ) Is prevented. In addition, a sealant reservoir is formed at the fitting end due to the surplus of the sealant pressed by the press-fitting, thereby preventing the intrusion of the aqueous electrolyte solution.

[0010]

FIG. 1 is a view showing a housing connecting structure of a power steering apparatus according to a first embodiment of the present invention, in which (a) is a plan view showing a state before connection, and (b). Is a plan view after connection, and (c) is a vertical sectional view of (b). Since the present invention relates to a connection structure of a housing, illustration of members housed in the housing is omitted. In FIG. 1A, a pinion housing 1 for accommodating a rack and pinion gear is made of a magnesium alloy, has a cylindrical shape, and has a flange 1 on its outer peripheral surface.
a, and a projection 1b and a rib 1c for improving strength are protruded. In the vicinity of the left end of the pinion housing 1, a plurality of through holes 1d are formed at predetermined intervals in the circumferential direction. On the other hand, the cylinder tube 2 made of an aluminum alloy-based or iron-based metal is cylindrical, and a plurality of through holes 2d are formed at predetermined intervals in the circumferential direction near the right end.

From the state (a) in which the pinion housing 1 and the cylinder tube 2 are coaxially opposed to each other,
As shown in (b) and (c), the resin member 3 is formed by injection molding using a necessary mold, jig and the like. Thus, the pinion housing 1 and the cylinder tube 2 are firmly connected to each other by the resin member 3 that has been solidified by covering the respective ends of the pinion housing 1 and the cylinder tube 2 while entering the through holes 1d and 2d. This allows
The pinion housing 1 and the cylinder tube 2 are fixed via the resin member 3 without directly contacting each other. Therefore, the occurrence of corrosion in the pinion housing 1 made of a magnesium alloy is prevented.

FIG. 2 is a sectional view showing a housing connecting structure of a power steering apparatus according to a second embodiment. In FIG. 3A, the pinion housing 1 is made of a magnesium alloy as in the first embodiment, has a cylindrical shape, has a flange 1a on the outer peripheral surface, and a projection 1b and a rib 1c for improving strength. Is protruding. The left end side of the pinion housing 1 is formed to have a smaller diameter than the right end side as a fitting portion 1e. In the vicinity of the left end of the pinion housing 1, a plurality of through holes 1d are formed at predetermined intervals in the circumferential direction. On the other hand, the cylinder tube 2 made of an aluminum alloy-based or iron-based metal is cylindrical, and a plurality of through holes 2d are formed at predetermined intervals in the circumferential direction near the right end.

The pinion housing 1 and the cylinder tube 2 according to the second embodiment are connected to each other by the fitting portion 1e being pressed into the inner periphery of the cylinder tube 2. At this time, the through holes 1d and 2d are aligned with each other and form a plurality of communicating through holes.
From this state, the connection between the pinion housing 1 and the cylinder tube 2 is subjected to resin injection molding using a necessary mold, jig, or the like, and as shown in FIG.
The resin member 3 that has entered and solidified is formed. Thereby, the connecting portion between the pinion housing 1 and the cylinder tube 2 is completely covered by the resin member 3 and is not exposed. Therefore, even when the aqueous electrolyte solution is applied, the pinion housing 1 made of a magnesium alloy does not enter the contact portion between the dissimilar metals, thereby preventing corrosion. Further, the pinion housing 1 and the cylinder tube 2 are firmly fixed to each other by the press-fitting and the resin member 3.

FIG. 3 is a sectional view showing a housing connecting structure of a power steering apparatus according to a third embodiment. In FIG. 3A, the pinion housing 1 is made of a magnesium alloy as in the first embodiment, has a cylindrical shape, has a flange 1a on the outer peripheral surface, and a projection 1b and a rib 1c for improving strength. Is protruding. The left end side of the pinion housing 1 is formed to have a smaller diameter than the right end side as a fitting portion 1e. On the other hand, the cylinder tube 2 made of an aluminum alloy-based or iron-based metal has a cylindrical shape.

The pinion housing 1 and the cylinder tube 2 according to the third embodiment are connected to each other by the fitting portion 1e being pressed into the inner periphery of the cylinder tube 2 as shown in FIG. Further, as shown in (b), the epoxy-based cured paint 4 is applied to the outer peripheral surface from the cylinder tube 2 to the flange 1a of the pinion housing 1. As a result, the paint enters the interface between the pinion housing 1 and the cylinder tube 2 and cures to form a coating film. The epoxy-based cured paint 4 has a higher density and generates less air bubbles than the conventionally used phenol-based cured paint. In addition, it has good penetration into the interface. Therefore, the coating film of the epoxy-based cured paint 4 is excellent in waterproofness and durability. In this way, the coating film of the epoxy-based cured paint 4 covers the connecting portion between the pinion housing 1 and the cylinder tube 2 to prevent exposure, so that even when the electrolytic aqueous solution is applied to the connecting portion, the electrolytic aqueous solution dissolves between different metals. Does not penetrate the contact area. Therefore, the occurrence of corrosion in the pinion housing 1 made of a magnesium alloy is prevented.

FIG. 4 is a sectional view showing a housing connecting structure of a power steering apparatus according to a fourth embodiment. In the figure, the pinion housing 1 is made of a magnesium alloy as in the first embodiment, has a cylindrical shape, and has a flange 1a on the outer peripheral surface. The left end side of the pinion housing 1 is a fitting portion 1e. On the other hand, the cylinder tube 2 made of an aluminum alloy-based or iron-based metal has a cylindrical shape. In this embodiment, first, as shown in FIG.
The sealant 5 is applied to the outer peripheral surface of e. Here, the sealant 5 is a thermosetting and anaerobic curable acrylic or silicone resin. Also, the thickness of the coating is
The thickness is set to 10 to 25 μm according to the fitting length of e.

Next, as shown in FIG. 2B, the fitting portion 1e of the pinion housing 1 is pressed into the inner periphery of the cylinder tube 2. At this time, the necessary minimum amount of the sealant is
a, the sealant remains between the inner peripheral surface of the cylinder tube 2 and the outer peripheral surface of the fitting portion 1a, and the excess sealant is pressed down, and the sealant is placed between the flange 1a and the right end of the cylinder tube 2. The pool 5b is formed densely. The sealant reservoir 5 b is slightly raised from the surface of the cylinder tube 2. Thereafter, the seal film 5a is anaerobically cured, and the sealant reservoir 5b is thermally cured by using heating during the coating and curing treatment of the cylinder tube 2.

In the fourth embodiment configured as described above, the gap between the contact portion between the inner peripheral surface of the cylinder tube 2 and the outer peripheral surface of the fitting portion 1a is filled by the seal film 5a. In addition, the flange 1 is formed by the sealant reservoir 5b.
a and the right contact with the right end of the cylinder tube 2 are prevented. Also, the raised sealant reservoir 5b is
A gap is prevented from being formed between the flange 1a and the end surface of the cylinder tube 2, and the intrusion of the aqueous electrolyte solution is prevented. Therefore, the occurrence of corrosion in the pinion housing 1 made of a magnesium alloy is prevented.

[0019]

The present invention configured as described above has the following effects. According to the housing structure of the power steering device of the first aspect, the resin member acts to fix the pinion housing and the cylinder tube to each other while maintaining mutual insulation between the pinion housing and the cylinder tube. Direct contact with the cylinder tube, which is a metallic or iron-based metal, is prevented. Therefore, corrosion of the pinion housing can be prevented.

According to the housing structure of the power steering device of the second aspect, the pinion housing and the cylinder tube, which are made of different metals, come into contact with each other by fitting, but the connection between the pinion housing and the cylinder tube by the resin member. Since the outer surface of the portion is covered, it is possible to prevent the aqueous electrolyte solution from touching the contact portion between dissimilar metals. Therefore, corrosion of the pinion housing can be prevented.

According to the housing structure of the power steering device of the third aspect, the resin flows into the plurality of holes and is solidified, whereby a strong connection state can be obtained.

According to the housing structure of the power steering device of the fourth aspect, the epoxy-based paint easily enters the interface between the pinion housing and the cylinder tube and is excellent in waterproofness and durability, so that a stable corrosion prevention effect is obtained. Is obtained.

According to the housing structure of the power steering apparatus of the fifth aspect, although the pinion housing and the cylinder tube, which are dissimilar metals, are fitted to each other, the space (gap) is generated due to the sealing agent interposed therebetween. To prevent. In addition, a sealant reservoir is formed at the fitting end due to the surplus of the sealant pressed by the press-fitting, thereby preventing the intrusion of the aqueous electrolyte solution. Thus, corrosion of the pinion housing can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view and a sectional view showing a housing connecting structure of a power steering device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a housing connection structure of a power steering device according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a housing connecting structure of a power steering apparatus according to a third embodiment of the present invention.

FIG. 4 is a sectional view showing a housing connecting structure of a power steering apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pinion housing 1d through-hole 1e fitting part 2 cylinder tube 2d through-hole 3 resin member 4 epoxy-based hardening paint 5 sealant

Claims (5)

[Claims] A rack and pinion gear is housed, a pinion housing made of a magnesium alloy is housed, and a cylinder that receives a hydraulic pressure to generate a steering assist force is housed and connected to a cylinder tube made of an aluminum or iron metal. In the housing coupling structure of the configured power steering device, in a state where the end of the pinion housing and the end of the cylinder tube are close to each other, the pinion housing and the cylinder tube are interposed with a resin member interposed therebetween. A housing connection structure for a power steering device, which is fixed to each other. A rack and pinion gear is housed therein, and a pinion housing made of a magnesium alloy is housed with a cylinder which receives a hydraulic pressure to generate a steering assist force, and is connected to a cylinder tube made of an aluminum or iron metal. In the housing coupling structure of the power steering device thus configured, an end of the pinion housing and an end of the cylinder tube are fitted to each other, and at least an outer surface of a connection portion between the pinion housing and the cylinder tube is made of resin. A housing connection structure for a power steering device, characterized by being covered with a member. 3. The resin member is formed by injection molding, and a plurality of holes for flowing resin are provided near an end of the pinion housing and near an end of the cylinder tube. A housing connecting structure for a power steering device according to claim 1 or 2. 4. A rack and pinion gear is housed therein, and a pinion housing made of a magnesium alloy is housed, and a cylinder for receiving a hydraulic pressure to generate a steering assist force is housed and connected to a cylinder tube made of an aluminum or iron metal. In the housing coupling structure of the configured power steering device, one of the end of the pinion housing and the end of the cylinder tube is press-fitted into the other to join them together, and the joint is joined to both members. A housing connection structure for a power steering device, characterized in that an epoxy-based paint is applied and cured in a covering form. 5. A rack / pinion gear is housed, a pinion housing made of a magnesium alloy is housed, and a cylinder for receiving a hydraulic pressure to generate a steering assist force is housed, and a cylinder tube made of an aluminum or iron metal is connected. In the housing connecting structure of the power steering device thus configured, the end of the pinion housing and the end of the cylinder tube are mutually insulated by press-fitting one end into the other with a sealant interposed therebetween. A housing connection structure for a power steering device, wherein the housing connection structure is fitted.