JP2010127226A - Device and method for inspecting valve clearance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inspect propriety of a valve clearance with a simple device and method. <P>SOLUTION: The propriety of the valve clearance is inspected based on a valve opening angle θ<SB>0</SB>calculated from a rotation angle of a cam, without determining the propriety by directly measuring the valve clearance. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus and method for inspecting whether or not a valve clearance formed between a cam for opening and closing a valve of a cylinder head and a cam follower is appropriate.

  For example, a cylinder head of an automobile engine is provided with an intake / exhaust valve, which is opened and closed by a cam and a cam follower. A minute gap called a valve clearance is formed between the cam and the cam follower. If this valve clearance is too small, the valve may not be completely closed, and combustion gas leakage may occur. On the other hand, if the valve clearance is too large, the valve will not open sufficiently, and there is a risk of hindering supply and exhaust. Therefore, it is necessary to confirm whether or not the valve clearance is set within an appropriate range after mounting the valve on the cylinder head.

  Conventionally, for example, confirmation has been performed by measuring the valve clearance using an apparatus as disclosed in Patent Document 1. This device measures and measures the valve clearance by measuring the displacement of the upper end of the cam relative to the cam follower (lifter) while rotating the cam.

JP 2005-54728 A

  However, as described above, it is not easy to measure the displacement of the upper end portion of the rotating cam, and there is a problem that the apparatus becomes complicated and large in order to measure with high accuracy.

  An object of the present invention is to inspect the appropriateness of the valve clearance with a simple device and method.

In order to solve the above-mentioned problems, the present invention is an apparatus for inspecting a valve clearance formed between a cam that opens and closes a valve of a cylinder head and a cam follower, and includes a drive unit that rotates the cam, and a valve A displacement meter for detecting the displacement from the reference position, an angle detection unit for detecting the rotation angle of the cam, the rotation angle θ ₁ of the cam when the displacement when the valve is lowered reaches a predetermined value, and the valve from the rotation angle theta ₂ of the cam when the displacement at the time of rise reaches a predetermined value, and a calculator for calculating a valve opening angle theta ₀ represented by these differences, the valve open angle theta ₀ by the computing unit proper range A determination unit that determines whether the output is within the range, and an output unit that outputs a result of the determination unit.

In the present invention, paying attention to the fact that there is a correlation between the valve clearance and the cam rotation angle, the cam clearance is not determined by directly measuring the valve clearance as in the prior art, but by determining whether it is appropriate or not. The appropriateness of the valve clearance is inspected by the valve opening angle θ ₀ calculated from the rotation angle. Thereby, since it is sufficient to detect only the displacement of the valve that moves linearly and the rotation angle of the cam, the apparatus can be simplified and made compact.

Ideally, the cam opening angles θ ₁ and θ ₂ are detected at the moment of contact / separation between the cam and the cam follower, that is, the predetermined value of the valve displacement is made as close to zero as possible. However, in consideration of variations in the processing accuracy and assembly accuracy of each member, it is impossible in practice to set the predetermined value to 0, so the cam rotation angle when the valve is displaced by the predetermined value d is detected. There is a need to. The predetermined value d of the valve displacement can be set as follows.

That is, the displacement D of the valve when the cam is rotated is, for example, as shown in FIG. 7, a constant speed region A that rises or descends relatively small with respect to the cam rotation angle θ, and the cam rotation angle θ. The behavior is such that it has an acceleration region B in which the ascending or descending width gradually increases with an increase, and the operating region C that rises or descends relatively large with respect to the cam rotation angle θ. For example, the rotation angle of the cam necessary for displacing the valve by ΔD is large in the constant speed region A where the change rate is small and small in the operation region C where the displacement rate is large (Δθ _A > Δθ _C ). From this, the change of the valve opening angle θ _{0 with} respect to the valve clearance Vc is graphed as shown in FIG. If the predetermined value d of the valve displacement is set within the constant speed region A, the slope of the graph increases (see graph A in FIG. 8). As a result, the range of the valve opening angle with respect to the appropriate range of the valve clearance becomes large, and when the valve clearance slightly deviates from the appropriate range, it appears as a relatively large valve opening angle difference Δθ ₀ , so the valve opening angle θ ₀ It is easy to determine whether or not is within an appropriate range. On the other hand, if the predetermined value d of the valve displacement is set within the range of the operation region C, the slope of the graph becomes small (see graph C in FIG. 8). As a result, the valve opening angle range θ ₀ ′ with respect to the appropriate range of the valve clearance becomes small, and when the valve clearance slightly deviates from the appropriate range, it appears only as a relatively small valve opening angle difference Δθ ₀ ′. It is difficult to determine whether or not the valve opening angle θ ₀ is within an appropriate range. As described above, the predetermined value d of the valve displacement is preferably set within the constant speed region A.

According to the above device, the displacement amount from the reference position of the valve is detected while rotating the cam, and when the displacement amount of the valve reaches a predetermined value when the valve is lowered, the rotation angle θ ₁ of the cam at this time is detected. When the valve displacement reaches a predetermined value when the valve is raised, the cam rotation angle θ ₂ at this time is detected, and the valve opening angle θ ₀ represented by the difference between the detected θ ₁ and θ ₂ is detected. To determine whether or not the valve opening angle θ ₀ is within a predetermined range, it is possible to determine whether or not the valve clearance is within an appropriate range.

  As described above, according to the present invention, the suitability of the valve clearance can be inspected with a simple device and method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows the periphery of a valve 20 attached to the cylinder head 1. The valve 20 is provided to open and close the intake port 2 (or the exhaust port, hereinafter the same) of the cylinder head 1, and a valve head 21 that closes the opening of the intake port 2 and a valve stem 22 that extends upward from the valve head. And have. An annular groove is formed in the upper end portion of the valve stem 22, and a retainer 30 is attached to the annular groove via a cotter. A spring 40 is arranged in a compressed state between the retainer 30 and the cylinder head 1. The valve 20 is urged upward by the elastic repulsive force of the spring 40, so that the intake port 2 is normally closed by the valve head 21.

  A lifter 50 is attached to the upper end of the valve 20, and a cam 10 is disposed above the lifter 50. The lifter 50 functions as a cam follower for the cam 10 and is slidable with respect to the cylinder head 1. The cam 10 is attached to the camshaft 11 and has a non-circular cross section. A predetermined valve clearance Vc is formed between the cam 10 and the lifter 50.

  FIG. 2 shows an inspection device 60 for inspecting the suitability of the valve clearance Vc. The inspection device 60 includes a drive unit (not shown) that rotationally drives the cam 10, an encoder 61 as an angle detection unit, a displacement meter 62 that measures the displacement of the valve 20, and a calculation unit 63 that calculates a valve opening angle. And a determination unit 64 that determines the suitability of the valve clearance from the calculation result of the calculation unit 63, and an output unit 65 that outputs the determination result of the determination unit 64.

  The encoder 61 transmits the rotation angle θ from the reference position of the cam 10 to the calculation unit 63 as an encoder signal. The displacement meter 62 measures the displacement of the upper surface of the lifter 50 attached to the valve 20 from the reference position, and indirectly measures the displacement of the valve 20. The displacement meter 62 is not limited to this, and for example, the displacement of the valve 20 may be directly measured.

The displacement of the valve 20 detected by the displacement gauge 62, a cam rotation angle transmitted from the encoder 61 is transmitted to the calculation unit 63 calculates the valve opening angle theta ₀ based on these. A method for calculating the valve opening angle θ ₀ will be described in detail below.

  FIG. 3A shows a state in which the valve 20 is at the upper end position, that is, the valve head 21 closes the intake port 2 and the cam 10 has the protruding portion directed upward. In this embodiment, the cam rotation angle θ and the displacement of the lifter 50 in this state are used as the reference position. The cam 10 is rotated in the direction of the arrow from this reference position, and is brought into contact with the upper surface of the lifter 50 (FIG. 3B). When the rotation of the cam 10 proceeds, the lifter 50 and the valve 20 are pushed down, the valve head 21 is separated from the cylinder head 1 and the valve is opened. Thereafter, the lifter 50 and the valve 20 continue to descend and reach the bottom dead center (FIG. 3C). When the bottom dead center is exceeded, the lifter 50 and the valve 20 rise, and when the valve head 21 comes into contact with the cylinder head 1, the raising stops (FIG. 3 (d)). When the cam 10 is further rotated, the cam 10 moves away from the upper surface of the lifter 50.

Thus the cam 10 when rotates once, the cam rotation when the valve 20 begins to open the cam rotation angle theta ₁ of (FIG. 3 (b)), when fully closed the valve 20 (FIG. 3 (d)) The angle θ ₂ is sent to the calculation unit 63. At this time, when the amount of displacement of the valve 20 detected by the displacement meter 62 (the amount of displacement of the lifter 50 in the illustrated example) reaches a predetermined value d when the valve is lowered, it is considered that the valve is opened, and the cam rotation angle at this time is determined. θ ₁ is transmitted from the encoder 61 to the calculation unit 63. Further, when the displacement of the valve 20 reaches a predetermined value d when the valve is raised, it is considered that the valve is closed, and the cam rotation angle at this time is transmitted to the calculation unit 63 as θ ₂ . As described above, the predetermined value d of the valve displacement amount is preferably provided within the range of the constant velocity region A of the valve displacement in order to facilitate the determination of the appropriateness of the valve clearance. Specifically, the predetermined value d is set such that the displacement from the reference position is 0.03 to 0.20 mm, preferably 0.05 to 0.10 mm, for example, 0.07 mm.

The computing unit 63 computes the valve opening angle θ ₀ (see FIG. 4) represented by the difference θ ₂ −θ ₁ based on the transmitted cam rotation angles θ ₁ and θ ₂ . The value of the valve opening angle theta ₀ is sent to the determination unit 64 determines the appropriateness of the valve clearance from this value. For example, if the valve clearance is too small, as shown in FIG. 5, the contact between the cam 10 and the lifter 50 is accelerated (that is, θ ₁ is decreased) and the separation between the two is delayed (that is, θ ₂ is increased). As a result, the valve opening angle θ ₀ ′ increases. On the other hand, if the valve clearance is too large, as shown in FIG. 6, the contact between the cam 10 and the lifter 50 is delayed (that is, θ ₁ is increased) and the separation between the two is accelerated (that is, θ ₂ is decreased). As a result, the valve opening angle θ ₀ ″ becomes smaller. Therefore, if the valve opening angle θ ₀ is within an appropriate range, it can be determined that the valve clearance is appropriate.

  In this way, the determination result by the determination unit 64 is output to the output unit 65 (for example, a monitor), and the quality of the assembled product can be determined.

Thus, by determining the appropriateness of the valve clearance based on the valve opening angle θ ₀ obtained from the cam rotation angle θ, a conventional large-scale facility for detecting the upper end position of the cam is not required, and the compactness is achieved. In addition, the inspection can be performed easily.

  The present invention is not limited to the above embodiment. For example, although the case where the cam follower is the lifter 50 is shown above, for example, when the valve is pushed down via the rocker arm, a valve clearance is formed between the cam and the rocker arm, and the rocker arm becomes the cam follower. .

It is sectional drawing which shows the valve | bulb vicinity of a cylinder head. It is a block diagram which shows a valve clearance inspection apparatus. (A)-(d) is sectional drawing which shows a mode that a valve is opened and closed with a cam. It is sectional drawing which shows valve opening angle (theta) ₀ in case a valve clearance is in an appropriate range. FIG. 6 is a cross-sectional view showing a valve opening angle θ ₀ ′ when the valve clearance is too small. FIG. 6 is a cross-sectional view showing a valve opening angle θ ₀ ″ when the valve clearance is excessive. It is a graph which shows the valve displacement amount D with respect to rotation angle (theta) of a cam. It is a graph which shows valve opening angle (theta) ₀ with respect to valve clearance Vc.

Explanation of symbols

1 Cylinder Head 2 Intake Port 10 Cam 11 Cam Shaft 20 Valve 21 Valve Head 22 Valve Stem 30 Retainer 40 Spring 50 Lifter 60 Inspection Device Vc Valve Clearance

Claims (3)

A device for inspecting the suitability of a valve clearance formed between a cam for opening and closing a valve of a cylinder head and a cam follower,
A drive unit that rotates the cam, a displacement meter that detects displacement from the reference position of the valve, an angle detection unit that detects the rotation angle of the cam, and a cam when the displacement when the valve is lowered reaches a predetermined value. rotation angle theta ₁ and calculates the valve opening angle theta ₀ represented by the difference between the rotational angle theta _2, the theta ₁ and theta ₂ of cam when the displacement at the time of rise of the valve reaches a predetermined value calculation A valve clearance inspection device comprising: a determination unit; a determination unit that determines whether the valve opening angle θ ₀ by the calculation unit is within an appropriate range; and an output unit that outputs a result of the determination unit.   The valve moves up and down in a manner having a constant speed region where the valve rises or descends relatively small with respect to the cam rotation angle and an operation region where the valve rises or descends relatively large with respect to the cam rotation angle, The valve clearance inspection apparatus according to claim 1, wherein the predetermined value of the displacement of the valve is provided within a constant speed region. A method for inspecting the suitability of a valve clearance formed between a cam that opens and closes a valve of a cylinder head and a cam follower,
A step of detecting the amount of displacement from the reference position of the valve while rotating the cam, a step of detecting the rotation angle θ ₁ of the cam at this time when the amount of displacement of the valve reaches a predetermined value when the valve is lowered, If the displacement of the valve reaches a predetermined value at the time of ascent, the process of detecting the cam rotation angle θ ₂ at this time and the valve opening angle θ ₀ represented by the difference between the detected θ ₁ and θ ₂ a step of calculating, by the valve opening angle theta ₀ is determined whether it is within the predetermined range, the valve clearance inspection method comprising the step of examining whether the valve clearance is within the appropriate range.

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