JP2000120408A - Knockdown camshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing process number, and prevent an increase in a cost by using grooves arranged in an inside diameter of an installing part as lubrication of a cam driving gear and a lubricating oil passage between cam tappets. SOLUTION: A camshaft 1 has a hollow shaft 2, a partially expansible carbon steel material is used, and a sub-gear 6 and a cam lobe 20 for slidably contacting with a main gear 4 and a journal 22 are installed in a prescribed position. Plural grooves are arranged in the shaft direction on the inner peripheral surface of the main gear 4. When the shaft 2 is expanded, the outer peripheral part is deformed in a cross-sectional projecting shape, so that clearance is generated without completely blocking up the grooves. Then these grooves are used as a lubricating oil passage. That is, lubricating oil introduced up to the end surface of the main gear 4 by passing through a lubricating oil groove of the journal 22 is introduced inside the gear by passing through the groove, and is introduced between a pin and a torsion spring to thereby prevent abrasion between the sub-gear 6 and the shaft 2 and abrasion between the pin and the torsion spring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft used as an opening / closing mechanism of a valve of an internal combustion engine such as an engine, and more particularly to an improvement of a camshaft to which a cam, a journal bearing and the like are fixed.

[0002]

2. Description of the Related Art In driving between cams of a DOHC engine, a mechanism using a scissor gear as a mechanism for reducing backlash is well known. A scissor gear mechanism using a scissor gear applies torsional force in the rotational direction by a torsion spring attached between a main gear and a sub gear, and absorbs backlash by pinching a mating gear. FIG. 8 is a partial sectional view of a conventional camshaft to which a scissors gear mechanism is applied.
The configuration of a conventional camshaft employing a scissors gear mechanism will be described with reference to the drawings.

A main gear 104 is press-fitted into the step of the hollow shaft 102. The main gear has a pin 108
The other end of the pin 108 is provided with a C-shaped torsion spring 11.
0 is attached.

On the other hand, the other end (not shown) of the torsion spring 110 is mounted on the opening of the sub gear 106 via a pin 108, and the inner diameter of the sub gear 106 is slidably attached to the step of the shaft 102. Have been. Further, a retaining ring 118 is mounted to prevent the main gear 104 and the sub gear 106 from moving leftward in the axial direction (in the drawing) of the step portion of the shaft 102. Further, a seal member 116 for preventing leakage of lubricating oil is mounted on the left side of the retaining ring 118 in the axial direction.

In the above-described configuration, since the sub gear 106 moves in the circumferential direction, a lubricating oil is required on the contact surface between the camshaft 102 and the sub gear 106. Generally, the engine oil has an inner diameter 112 of the camshaft 102.
And a small-diameter hole 114 extending radially outward therefrom as a lubricating oil passage. The sub-gear 106 is in contact with the camshaft 102, and the sub-gear 106 is
This is a configuration that is guided to a portion that comes into contact with the pin 0 and the pin 108.

[0006]

When the inner diameter of the camshaft is used as a lubricating oil passage, the camshaft formed by the current manufacturing process (casting, forging, assembly type) has the radius of the camshaft which is the inlet and outlet of the lubricating oil. Two or more oil holes extending in the direction are required. Therefore, in the configuration of the conventional camshaft, the number of steps increases, and the manufacturing cost increases.

[0007]

In order to solve the above-mentioned problems, an assembling camshaft according to the present invention is configured by assembling parts such as gears and cam lobes on a hollow shaft. An assembled camshaft characterized in that the grooves provided are used as lubricating oil passages for lubricating a cam driving gear and for lubricating between a cam and a tappet.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A groove provided on the inner diameter of a cam lobe or the like is used as a lubricating oil passage to guide lubricating oil from the adjacent journal portion into the scissor gear.

[0009]

FIG. 1 is a partial front view of an assembled camshaft 1 according to a first embodiment of the present invention. The configuration of the assembled camshaft 1 will be described with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals.

The camshaft 1 has a hollow shaft 2 and is preferably made of carbon steel which is capable of partially expanding the shaft 2. At a predetermined position of the shaft 2, a main gear 4 fastened to the shaft, a sub gear 6 (scissors gear) slidably in contact with the journal, and a cam lobe 20 are mounted separately in the axial direction.

FIG. 2 is a partial front view showing a state in which the assembled camshaft 1 of FIG. 1 is incorporated in a cylinder head (not shown).

As can be seen from FIG.
Is mounted inside the cylinder head by the journal cap 24. The journal cap 24 has a substantially semicircular cross section at the center in the longitudinal direction, and is formed of a substantially flat flange at both ends. Openings are provided in the flat portions at both ends, and the camshaft 1 can be fixed in the cylinder head using a fixing member or the like.

FIG. 3 is a front view showing the shape of the journal 26 on the cylinder head side. The broken line in the drawing is an imaginary line showing the case where the camshaft 1 is mounted on the head-side journal 26.

The head-side journal 26 has substantially the same shape as the journal cap 24 shown in FIG. 2, and includes a central portion 26b having a substantially semicircular cross section in the longitudinal direction, and flanges 26a and 26c having both ends substantially flat. Become. A lubricating oil passage 29, which is a groove, is provided in the axial direction between the central portion 26b and one flange 26a. further,
The groove 28 is formed at a central portion 26b from substantially the center of the lubricating oil passage 29.
And the end of the groove 28 is connected to an opening 30 penetrating the central portion 26b in the thickness direction.

The journal 22 is provided with a lubricating oil opening (not shown) communicating with the opening 30 of the head-side journal 26, and lubricating oil to the journal 22 is supplied to a lubricating oil passage (not shown) in the cylinder head. The lubricating oil is further guided to the end face of the main gear 4 and the end face of the cam lobe 20 through the opening 30 and the lubricating oil passages 28 and 29.

FIG. 4 shows the main gear 4 shown in FIG.
It is sectional drawing cut | disconnected along IV-IV. As shown in the figure, by expanding the shaft 2, the shaft 2 is expanded.
Is mounted on the inner peripheral surface of the main gear 4.

On the other hand, a plurality of grooves 34 extending in the axial direction are provided in the inner peripheral surface of the main gear 4 in the circumferential direction. With this configuration, when the shaft 2 is expanded, the outer peripheral portion of the shaft 2 facing the groove 34 is deformed into a convex cross section, and the main gear 4 is mounted. Actually, the convex portion of the shaft 2 protruded by the pipe expanding process does not completely close the groove 34, and a gap is generated.

Therefore, the present invention further utilizes the groove 34 as a lubricating oil passage. The lubricating oil guided to the end face of the main gear 4 through the lubricating oil groove of the journal is guided to the inside of the gear through the groove 34 and is guided between the pin and a torsion spring (not shown). As a result, the sub gear 6 and the shaft 2
Wear between the pins and between the pin and the torsion spring can be prevented.

Next, the lubricating oil passage provided in the cam lobe 20 will be described with reference to FIG. FIG. 5 is a sectional view of the cam lobe 20 shown in FIG. 1 taken along the line VV. As shown in the figure, the cam lobe 20 is mounted on the outer peripheral surface of the shaft 2 by expanding the shaft 2.

On the other hand, on the inner peripheral surface of the cam lobe 20, a plurality of grooves 36 extending in the axial direction like the main gear 4 are provided in the circumferential direction. With this configuration, when the shaft 2 is expanded, the outer peripheral surface of the shaft 2 facing the groove 36 is deformed into a convex cross section, and is mounted on the cam lobe 20. In fact, the convex portion of the shaft 2 protruded by the pipe expanding process does not completely close the groove 36, and a gap is generated.

Like the gear 2, the groove 36 provided in the cam lobe 20 is used as a lubricating oil passage. With this configuration, the lubricating oil guided to the end face of the cam lobe 20 through the lubricating oil groove 36 of the journal 22 passes through the groove 36, passes through the inside of the cam lobe, is guided to the space on the opposite side of the cam lobe 20, and lubricates between the cam and tappet. I do.

According to this construction, the lubricating oil is supplied to the inner surface of the scissor gear and the opposite surface of the cam lobe 20 without providing an opening for lubricating oil in the inner surfaces of the scissor gear and the cam lobe 20 mounted on the shaft 2. It is possible to guide.

An assembled camshaft 60 according to a second embodiment of the present invention will be described with reference to FIGS.

FIG. 6 is a front view showing a state in which the assembled camshaft 60 according to the second embodiment is incorporated into a cylinder head (not shown) via the journal cap 44. The second embodiment has a configuration in which the cam lobe 20 in the first embodiment is replaced with a thrust receiving member 50, and the thrust receiving member 50 is mounted at a predetermined position on the shaft 42. Further, the cam lobes 46 and 48 are provided with thrust bearing members 50.
It is mounted at a predetermined position on the shaft 42 so as to be spaced apart from and opposed to the shaft 42.

The lubricating oil to the journal 54 is guided from a lubricating oil passage (not shown) of the cylinder head. A lubricating oil passage is formed in a chamfered portion provided on the journal cap 44 to guide the lubricating oil to the surface where the journal 54 contacts the thrust receiving member 50.

Next, referring to FIG.
A configuration for guiding the lubricating oil into the inside will be described. FIG.
FIG. 7 is a sectional view taken along line VII-VII shown in FIG. 6. A plurality of grooves 52 extending in the axial direction are provided in the inner peripheral surface of the thrust receiving member 50 in the circumferential direction. With this configuration, when the shaft 42 is expanded, the outer peripheral surface of the shaft 42 facing the groove 52 is deformed into a convex cross section, and is mounted on the thrust receiving member 50. Actually, the convex portion of the shaft 42 protruding in the pipe expanding process does not completely close the groove 52, and a gap is generated.

As in the first embodiment, the thrust receiving member 50
Are further used as a lubricating oil passage. With this configuration, the lubricating oil guided to the end surface of the thrust receiving member 50 through the lubricating oil passage of the journal cap 44 passes through the groove 52, passes through the inside of the thrust receiving member 50, and enters the space on the opposite surface side of the thrust receiving member 50. guided by,
The contact surfaces between the cam lobes 46 and 48 and the tappet and the like (not shown) are lubricated.

With this structure, it is possible to guide the lubricating oil between the cam and the taper without forming a hole in the thrust receiving member 50 only by providing the lubricating oil opening in the journal 54. Therefore, the camshaft 60 has a very simple configuration, and the number of processing steps can be reduced.

By the way, in the first and second embodiments,
The members (plugs, lids) for sealing the lubricating oil are not shown. However, it goes without saying that a seal member can be attached to the shaft end portion or the like as needed.

[0030]

As described above, according to the present invention, it is not necessary to machine a hole to form a lubricating oil passage.
The number of steps can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial front view of a camshaft according to a first embodiment.

FIG. 2 is a partial front view showing a state where the camshaft according to the first embodiment is incorporated in a cylinder head.

FIG. 3 is a front view showing a shape of a journal on a cylinder head side.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view taken along line VV in FIG. 1;

FIG. 6 is a partial front view showing a state where the camshaft according to the second embodiment is incorporated in a cylinder head.

FIG. 7 is a sectional view taken along the line VII-VII of FIG. 6;

FIG. 8 is a partial cross-sectional view showing a lubricating oil path of a conventional camshaft.

[Explanation of symbols]

 1, 60 Camshaft 2, 42 Shaft 4 Main gear 6 Sub gear 20, 42, 48 Cam lobe 22, 54 Journal 50 Thrust receiving member

Claims (1)

[Claims] 1. An assembling camshaft in which parts such as gears and cam lobes are assembled to a hollow shaft. Grooves provided on the inner diameter of the parts to be assembled are used to lubricate cam drive gears and to provide a space between the cam and tappet. An assembled camshaft characterized in that it is a lubricating oil passage for performing lubrication and the like.