JPH0596403U - Camshaft - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a long camshaft for an internal combustion engine that does not require a new large-scale sintering furnace when manufacturing a long camshaft. . [Structure] Camshaft pieces 1, 2 in which cam lobes 4, 5, 6, 7 made of a sintered alloy are integrally diffusion-bonded to a steel pipe 3 are prepared. The joining journal portion 9 is integrally joined to one end portion of the camshaft piece, and the joining journal portions are joined together by welding to form a long camshaft. [Effect] Secure stable quality and good workability,
It is possible to manufacture a durable long camshaft without causing a significant increase in cost. The integrated joint journal portion functions as the journal portion of the long camshaft.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a camshaft for an internal combustion engine, and is particularly suitable for a long camshaft incorporated in a diesel engine, and a composite camshaft piece made of a combination of different materials such as a sintered alloy and steel. The present invention relates to a long camshaft which is fixed by welding more than one unit.

[0002]

[Prior Art]

 In recent years, the camshafts for opening and closing valves of internal combustion engines have been reduced in weight like other engine parts from the viewpoint of improving fuel efficiency. At the same time, it is required to improve wear resistance and heat resistance and secure rigidity at the same time. In the past, especially in internal combustion engines that use gasoline as a fuel, a composite body made of iron alloy and steel has been used by baking (sintering diffusion bonding) a molded body in which a cam lobe is formed of iron alloy powder to a steel pipe. With good results. This is a combination of a ferrous alloy sintered cam lobe, which has excellent wear resistance, and a steel pipe shaft, which is lightweight and has excellent rigidity.

[0003]

[Problems to be solved by the device]

 In order to manufacture a composite cam shaft by this baking, generally, a cam lobe of a powder metal compact is fixed to a steel pipe at a predetermined position by some means, and the whole is put into a sintering furnace and fixed by sintering. It is carried out. Therefore, a camshaft for a gasoline engine with a small cylinder volume does not require a particularly large sintering furnace because its total length is relatively short. However, the camshafts for diesel engines installed in large internal combustion engines are often several steps longer than gasoline engines, and problems arise with conventional methods. In other words, in many cases it is not possible to store a long camshaft in an existing sintering furnace, and even if it can be stored, there is no dimensional allowance, workability is poor, and temperature control is difficult. Is often reduced. It is also possible to install a new large-scale sintering furnace to match the long camshaft, but this will add equipment cost to the cost of the product, so unless a large amount is produced, it will be a large scale. It is not desirable to install a new furnace.

The present invention has been made in view of the above-mentioned problems, and assures stable quality and good workability without newly installing a large-scale sintering furnace, which causes a significant increase in cost. The aim is to provide a camshaft that is not long.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention relates to a camshaft having a steel pipe and a sintered alloy cam lobe integrally connected to the steel pipe by sintering diffusion bonding. A camshaft piece is formed by forming at least two camshafts, (b) a joining member is integrally provided on at least one end of the pipe of each camshaft piece, and (c) the at least two cams. The shaft piece is coaxially and integrally joined between the respective joining members, and the outer peripheral surface of the joined joining member after joining serves as a long camshaft.

[0006]

[Action]

 According to the camshaft of the present invention, a camshaft piece formed by temporarily fixing a cam lobe compact made of a sintered alloy to a steel pipe is sintered and diffusion bonded in a normal sintering furnace, and the cam lobe is made of steel. It adheres to the pipe integrally. At least two cam shaft pieces produced in this manner are coaxially joined by joining, for example, by joining members to obtain a long camshaft (700 mm or more).

[0007]

【Example】

 An embodiment of a camshaft according to the present invention will be described below with reference to FIGS. FIG. 1 is a vertical cross-sectional view of the long camshaft of the present embodiment centered on the joining point. In this embodiment, one long camshaft is shown by the left and right two camshaft pieces 1, 2. Since the camshaft pieces 1 and 2 are configured substantially symmetrically except for both ends (not shown), members having the same function and located at the same position are designated by the same reference numerals to avoid redundant description.

In the left camshaft piece 1, first, a plurality of sintered alloy cam lobes 4, 5, 6, 7 are formed on the outer peripheral surface of a steel cam pipe 3. The cam lobes are the exhaust side cam lobes 4 and 7 and the intake side cam lobes 5 and 6, and these cam lobes are positioned and assembled to the steel pipe 3 in the state of green compact or in the state of primary sintering and sintered in the furnace. As a result, it is formed on the circumferential surface of the cam pipe 3. At this time, the cam lobes 4, 5, 6, and 7 are simultaneously sintered, and at the same time, metallurgical bonding is promoted by diffusion into the steel pipe 3, and the cam lobes 4, 5, 6, and 7 are firmly bonded to the steel pipe 3. To be done.

Further, the tubular steel journal portion 8 is integrally joined to the cam pipe 3 by brazing, and the steel joining journal 9 is assembled to one end portion of the cam pipe 3. The joining journal 9 is composed of a columnar portion 9a mounted on the inner peripheral side of the cam pipe 3 and a flange portion 9b protruding outward in the radial direction from one end of the columnar portion 9a. The inner peripheral surface of the cam pipe 3 to which the columnar portion 9a of the joining journal 9 is attached has a slightly larger inner diameter than the other inner peripheral surfaces. In this embodiment, the inner diameter B of the portion where the columnar portion 9a is mounted is 21.6 mm, while the inner diameter A of the other portions is 20 mm. By the way, the outer diameter of the cam pipe is 30 mm. The cylindrical portion 9a is made relatively long to ensure the strength of this portion.

The journal portion 8 and the joining journal 9 are assembled to the cam pipe 3, and the journal 8 is fixed to the outer peripheral surface of the cam pipe 3 by brazing, and the cylindrical portion 9 a of the journal 9 is attached to the inner peripheral portion of one end portion of the cam pipe 3. Stick to the surface. Alternatively, when the cam lobes 4, 5, 6, 7 and the like are baked on the steel pipe 3, the joining journal 9 may be similarly assembled and brazing may be simultaneously performed in the sintering furnace.

Further, as shown in FIG. 2, the joint surface of the flange portion 9b of the joint journal 9 is formed with a notched edge portion 9c having a notched shape at its peripheral end, and is finished when the camshaft pieces 1 and 2 are welded. Make sure the surfaces are at the same level. That is, the camshaft pieces 1 and 2 to which the journals 8 and 9 are individually taken out from the sintering furnace are fixed and the respective cam phases are adjusted by a predetermined jig, and the camshaft pieces 1 and 2 are coaxial. The joining surfaces of the joining journal 9 are aligned so that Welding is performed by high-energy welding such as electron beam or laser, which has less welding distortion and can be completed in a short time. With this welding method, the amount of welded meat is extremely small, so it does not swell up to the surface so much, but since the peripheral edge of the joint surface is notched as shown in Fig. 2, the welded meat portion 10 is absorbed in this notch. The finished surface has no protrusions.

The joined journal portions 9 and 9 after joining are integrally supported by a bearing (not shown), and absorb or relieve direct stress applied to the joining surface, so that durability as a long camshaft is secured. ..

In the present embodiment, the joining journal 9 is made of steel as an integrated product, but it is also possible to make it partly hollow or entirely hollow to reduce the weight. It is also possible to use an alloy with excellent durability other than steel.

[0014]

[Effect of the device]

 As described above, according to the camshaft of the present invention, at least two camshaft pieces in which cam lobes are sintered and diffusion-bonded by using an existing sintering furnace without newly installing a large-scale sintering furnace are formed. However, since the joining journal surfaces are made into one camshaft by high-energy welding, it is possible to provide a long camshaft that ensures stable quality and good workability and does not significantly increase costs. Further, the joint journal surface is integrally supported by the bearing, so that the direct stress acting on the joint surface can be absorbed or relieved, and the durability as a long camshaft can be improved.

[0015]

[Brief description of drawings]

FIG. 1 is a vertical cross section of a long camshaft obtained according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical cross-sectional view showing a joint portion of the camshaft of FIG. 1, showing a joint surface before welding.

FIG. 3 is an enlarged vertical cross-sectional view showing a joint portion of the cam shaft of FIG. 1, showing a joint surface after welding.

[Explanation of symbols]

 1, 2 Camshaft piece 3 Cam pipe 4 Exhaust side cam lobe 5 Intake side cam lobe 6 Intake side cam lobe 7 Exhaust side cam lobe 8 Journal section 9 Joint journal

Claims (1)

[Scope of utility model registration request] 1. A camshaft having a steel pipe and a sintered alloy cam lobe integrally joined to the steel pipe by sintering diffusion bonding, wherein at least two camshafts are formed. A camshaft piece, wherein at least one end of the pipe of each camshaft piece is integrally provided with a joint member, and the at least two camshaft pieces are coaxially and integrally formed between the respective joint members. A long camshaft, wherein the outer peripheral surface of an integrally joined member that is joined and acts as a journal after joining.