JPH0972208A - Valve clearance detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly detect that valve clearance detected is out of a suitable range. SOLUTION: A cam 10 for reciprocating a valve 12 has a first valve-closing range in which the cam has a shape to close the valve at low closing speed and a second valve-closing range connecting to the first valve-closing range in which the cam has a shape to close the valve at higher closing speed than the closing speed of the first valve-closing range. This device has the cam which seats the valve in the first valve-closing range when valve clearance 20 is in a suitable range and which seats the valve in the second valve-closing range when valve clearance is out of a suitable range and a detection means 22 which detects the seating sound of the valve and judges whether the valve clearance is in the suitable range or not by the strength of the seating sound detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve clearance detecting device.

[0002]

2. Description of the Related Art In the case of an internal combustion engine in which a valve directly reciprocates by a cam, a rocker arm and a valve head in the case of an internal combustion engine in which a valve reciprocates between a cam and a valve head through a push rod and a rocker arm. And a valve clearance for releasing thermal expansion of the valve and bringing the valve into close contact with the valve seat. However, the valve wears because it collides with the valve seat while being exposed to high temperatures such as combustion gas.
Valve clearance will be reduced. As the valve wear progresses further, there is no valve clearance and therefore the valve is not in close contact with the valve seat and cannot seal the cylinder. For this reason, conventionally, the internal combustion engine is provided with a detection device for detecting that the valve clearance is out of the appropriate range. For example, a valve clearance detecting device disclosed in Japanese Patent Laid-Open No. 61-101611 has a pickup sensor for detecting a seating sound of a valve and a crank angle sensor for detecting a crank angle, and a crank in which the seating sound of the valve is detected. When the difference between the angle and the intended seating crank angle of the valve becomes slower than a predetermined range, it is determined that the valve clearance has become abnormally small.

[0003]

However, the internal combustion engine has a generation source that emits a noise larger than the seating sound of the valve, such as the combustion sound in the cylinder, and the general cam shape has a seating sound in order to reduce the noise. Is designed to be small, it is difficult to accurately detect the actual seating sound, and therefore the above-described conventional technique may not be able to accurately determine the valve clearance. An object of the present invention is to provide a valve clearance detection device that can accurately detect that the valve clearance is out of the proper range.

[0004]

A valve clearance detecting device according to the present invention according to claim 1 is a cam for reciprocating a valve, the first closing having a shape for closing the valve at a low valve closing speed. A valve section and a second valve-closing section that is a second valve-closing section that is continuous with the first valve-closing section and that is configured to close at a valve-closing speed that is higher than the valve-closing speed of the first valve-closing section. A cam having, wherein the valve is seated in the first closed section when the valve clearance is within the proper range, and the valve is seated in the second closed section when the valve clearance is outside the proper range, The present invention is characterized by including a seating sound of the valve and detecting means for judging whether or not the valve clearance is within an appropriate range from the intensity of the seating sound detected.
According to the present invention, when the valve clearance is out of the proper range, the valve is seated at a large closing speed in the second closing section, so that a large seating sound is generated, and the seating sound is detected to determine the valve clearance from the strength. It is determined whether it is within the proper range.

The valve clearance detecting device according to the present invention as defined in claim 2 is a cam for reciprocating a valve,
A first valve opening section having a shape for opening the valve at a low valve opening speed, and a second valve opening section continuous to the first valve opening section, the valve opening rate being higher than the valve opening speed of the first valve opening section. A cam having a second valve opening section configured to open at a valve opening speed, wherein the valve starts opening in the first valve opening section when the valve clearance is within an appropriate range, and the valve clearance is appropriate. When the valve is outside the range, the valve starts opening in the second valve opening section, and the collision noise between the cam and the valve is detected, and the valve clearance is within the proper range from the intensity of the detected collision noise. And a detection means for determining whether or not there is a certain one. According to the present invention, when the valve clearance is out of the proper range, the valve collides with the cam at a large valve opening speed in the second valve opening section, so a large collision noise is generated, and the collision noise is detected and the valve is detected based on its intensity. Determine whether the clearance is within the proper range.

[0006]

DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an overall view showing the vicinity of a cylinder of an internal combustion engine including a valve clearance detection device of the present invention. FIG. 2 shows the cam of the present invention.
In FIG. 1, 10 is a cam, 12 is an intake valve and an exhaust valve reciprocated by the cam 10 (hereinafter referred to as “valve”), 1
Reference numeral 4 denotes a cylinder, and 16 denotes a piston in the cylinder 14. When the base circle portion 34 of the cam 10 faces the valve 12, the valve 1 is provided between the base circle portion 34 and the cam 10.
A valve clearance 20 is provided to allow the thermal expansion of No. 2 to escape and to bring the valve 12 into close contact with the valve seat 18. Valve 12
Is urged by the compression spring 23 arranged around the stem 21 of the valve 12, and is pushed down by the lifting portion 30 of the cam 10 against the urging force of the compression spring 23 in the valve opening process, and is closed in the valve closing process. It is pushed up by the biasing force of the compression spring 23. Since the valves are closed by the urging force of the compression spring 23, a sound, that is, a seating sound is emitted when the valves 12 are seated on the valve seat 18. 22 is a determination device for determining whether or not the valve clearance 20 is within an appropriate range,
That is, it is a general digital computer. A pickup sensor 24 for detecting a seating sound and a crank angle sensor 26 for detecting a crank angle are connected to the digital computer 22.

Next, as shown in FIG. 2 showing the contour shape of the cam 10, the cam 10 of the present invention has a base circle portion 34 having a circular contour of the center C and an outside of the circle of the center C. And a lifting portion 30 having a bulged contour. The valve head is 0 when the valve 12 is in the base circular portion 34, and the valve head 3
When it is at 0, it gradually increases and gradually decreases from the maximum valve lift. The cam 10 further includes a maximum valve lift and a base circular portion 34.
The buffer portion 28 between and is provided with a transition portion 32 that is recessed inward from the contour that smoothly connects the base circular portion 34 and the lift portion 30 from the lift portion 30 to the base circular portion 34. The head reduction rate per crank angle of the distance from the center C in the transition section 32 is larger than the head reduction rate in the head section 30 near the transition section 32.

The lift with respect to the crank angle of the cam 10 having the above-described contour shape is shown in FIG. 3 and FIG. 4 which is a partially enlarged view thereof. 3 and 4, the vertical axis represents the lift (mm), the horizontal axis represents the crank angle (° CA), and the lift at the base circular portion 34 of the cam 10 is 0 mm. With particular reference to FIG. 4, crank angles 290-3
The lift characteristics up to 25 ° CA will be described. The head / crank angle in this range, that is, the head reduction rate is larger at a crank angle of 290 to 295 ° CA and is 295.
Smaller at ~ 312 ° CA, further 312-325 °
It is getting bigger in CA. The lift corresponding to the transition portion 32 of the cam 10 is in the range of 312 to 325 ° CA. Therefore, a section having a small head reduction rate is the first valve closing section A in the present application, and a section having a large head reduction rate is the second valve closing section B in the present application,
B '.

The speed with respect to the crank angle of the valve 12 reciprocated by the cam 10 having such a lift characteristic is shown in FIG. 5 and FIG. 6 which is a partially enlarged view thereof.
5 and 6, the vertical axis represents the valve speed (mm / ° C).
A), the horizontal axis represents the crank angle (° CA), and the speed of the valve 12 in the base circle portion 34 is 0 mm / ° CA. Similar to the above, referring to FIG. 6, crank angles 290 to 3
Explaining the valve speed over 25 ° CA, that is, the valve closing speed, the valve closing speed is proportional to the head decreasing rate, and is relatively large at the crank angle of 290 to 295 ° CA, but gradually decreases, and decreases at 295 to 312 ° CA. The valve closing speed is relatively small and constant, and is relatively large at 312 to 325 ° CA. Therefore, the section where the valve closing speed is small is the first valve closing section A, and the section where the valve closing speed is large is the second valve closing section B, B '.

In the cam 10 of the present invention, the valve 12 is initially set so as to be seated at a crank angle of about 300 ° CA. When the valve clearance 20 is within the proper range, the valve 12 is seated in the first valve closing section A, so that the valve closing speed is low and therefore the seating noise is low. However, when the valve 12 wears, the valve clearance 20 provided between the valve 12 and the cam 10 for releasing thermal expansion as described above decreases, and when the valve clearance 20 is out of the proper range, the seating timing of the valve 12 is delayed. The crank angle at which the valve 12 is seated becomes large. Therefore, since the valve 12 is seated in the second valve closing section B, the valve closing speed is increased and the seating noise is increased.

The seating sound of the valve 12 is detected by a pickup sensor 24 attached to the cylinder wall 22 and sent to the digital computer 22. The digital computer 22 is preset with a reference value when the valve clearance 20 is within the proper range. The digital computer 22 can determine whether or not the valve clearance 20 is abnormally small and is out of the proper range by comparing the sent signal with the reference value.

On the other hand, the valve head 36 may be worn and the valve clearance 20 may increase. At this time, if the valve closing timing of the valve 12 is advanced and the valve clearance 20 increases beyond the proper range, the second valve closing section is opened. At B ', the valve 12 becomes seated. Therefore, as in the case where the valve clearance 20 decreases, the seating noise increases, and the digital computer 22 determines that the valve clearance 20 is outside the proper range. When the valve clearance is out of the proper range, an abnormality in the valve clearance can be displayed to notify the driver. Conventionally, it was necessary to provide a crank angle sensor in order to detect the vibration of the seating sound, but in the present invention, the valve clearance can be determined only by the strength of the seating sound, so the structure of the valve clearance detection device is simple. become. The pickup sensor 24 described above can also be used as a knocking sensor generally arranged in an internal combustion engine. In this case, the seating noise of the valve may be detected except when the knocking sensor detects the presence or absence of knocking under high load.

When the crank angle at which the seating sound is detected is before the crank angle which is initially set, the valve clearance 20 is increasing, and when it is behind, the valve clearance 20 is decreasing. By using the angle sensor 26 to detect the crank angle at which the seating sound is detected in the second valve closing section B, B ′, the valve clearance 2
It is possible to identify whether 0 is abnormally decreased or abnormally increased. Further, the valve closing speeds of the second valve closing sections B and B ′ may be markedly different from each other, and whether the valve clearance is abnormally reduced or abnormally increased may be discriminated from the intensity of each seating sound. In this case, the crank angle sensor 2
6 is unnecessary. When the valve clearance 20 is abnormally reduced, in order to prevent the combustion gas from leaking through the gap between the valve and the valve seat and causing the valve melting loss, for example, the air-fuel ratio is increased to lower the combustion temperature. By knowing the increase / decrease of the valve clearance in this way, it is not necessary for the worker to judge the increase / decrease of the valve clearance during the readjustment work of the valve clearance, and therefore the adjustment work is reduced.

It is also possible to know from the valve clearance detection device that the combustion temperature in the cylinder is the heat resistance limit of each component of the internal combustion engine. For example, when the air-fuel ratio is brought close to the stoichiometric air-fuel ratio to improve the output, the combustion temperature rises and the wear of the valve progresses, so the valve clearance decreases. Therefore, if the heat resistant temperature of the valve is equal to the heat resistant temperature of other parts, it can be recognized that the combustion temperature at the time when the decrease in the valve clearance is detected is the heat resistant limit of each part. When it is determined that the valve clearance has decreased, if the combustion temperature is controlled so that the valve does not wear further, the combustion temperature does not rise above the heat resistant temperature of the valve, and therefore the heat resistant temperature is equal to the heat resistant temperature of the valve. Since the material may be used as an exhaust system component material such as a catalyst, it is possible to reduce the cost without using an excessively high heat-resistant material.

In the above-described embodiment, the second valve closing section is two sections which are continuous with the first valve closing section, but this does not limit the present invention, and either one of the two sections is provided. Only one of them may be the seating sound detection section. Of course, the present invention can be applied to an internal combustion engine in which a valve reciprocates via a push rod and a rocker arm.

In the first embodiment, the seating sound when the valve is closed is detected, but the collision sound between the cam and the valve when the valve is opened is detected, and the valve clearance is within the proper range from the intensity of the collision sound. It may be determined whether or not it is within. In the second embodiment, the base circular portion 34 is provided in the buffer portion 28 between the valve circular opening side base portion 34 of the cam 10 and the lift portion 30.
A transition portion 32 'that is recessed inward from the contour that smoothly connects the lift portion 30 and the lift portion 30 is provided (see FIG. 7). The lift of the cam 10 is shown in FIG. 8, and the valve opening speed at which the cam 10 opens the valve 12 when the valve is opened is shown in FIG. When the valve clearance 20 is within the proper range, the valve 12 starts opening in the first opening section D, and the valve clearance 20
When the valve clearance decreases and is out of the proper range, the valve 12 starts to open in the second opening section E, and when the valve clearance 20 increases and is out of the proper range, the valve 12 starts in the second closing section E ′. Open the valve. When opening the valve in the second valve opening section E, E ′, the valve opening speed is higher than the valve opening speed in the first valve opening section D, and therefore the speed in the normal direction at the collision point between the cam and the valve. Since the component is large, the collision noise is also large.
Therefore, it can be determined from the intensity of the collision sound whether the valve clearance is within the proper range. Other configurations, operations and modified examples are the same as those in the first embodiment.

[0017]

As described above, according to the valve clearance detecting device of the first aspect of the present invention, a large seating noise is generated only when the valve clearance is out of the proper range, so that the valve clearance is within the proper range. It is possible to easily determine whether or not the valve clearance is within the proper range while suppressing the seating noise at this time to be low.

According to the valve clearance detecting device of the second aspect of the present invention, since a large collision noise is generated only when the valve clearance is out of the proper range, the collision noise when the valve clearance is in the proper range. It is possible to easily determine whether or not the valve clearance is within the proper range while keeping the value low.

[Brief description of drawings]

FIG. 1 is an overall view around a cylinder of an internal combustion engine including a valve clearance detection device of the present invention.

FIG. 2 is an outline view showing a contour shape of a cam according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a lift with respect to a crank angle of the cam of FIG.

FIG. 4 is a partially enlarged view of FIG.

5 is a diagram showing a valve closing speed with respect to a crank angle of a valve reciprocated by the cam of FIG.

FIG. 6 is a partially enlarged view of FIG. 5;

FIG. 7 is an outline view showing a contour shape of a cam according to a second embodiment of the present invention.

8 is a diagram showing a lift with respect to a crank angle of the cam of FIG.

9 is a diagram showing a valve opening speed with respect to a crank angle of a valve reciprocated by the cam of FIG. 7. FIG.

[Explanation of symbols]

 10 ... Cam 12 ... Valve 20 ... Valve clearance 22 ... Digital computer 24 ... Pickup sensor A ... First valve closing section B, B '... Second valve closing section D ... First valve opening section E, E' ... Second opening Valve section

Claims (2)

[Claims] 1. A cam for reciprocating a valve, the first valve closing section having a shape for closing the valve at a low valve closing speed,
A cam having a second valve closing section continuous to the first valve closing section, the second valve closing section having a shape for closing the valve at a valve closing speed higher than the valve closing speed of the first valve closing section. The valve seats in the first closed section when the valve clearance is within the proper range, and the seating sound of the valve when the valve is seated in the second closed section when the valve clearance is outside the proper range. And a detection unit that determines whether the valve clearance is within an appropriate range based on the detected intensity of the seating sound. 2. A cam for reciprocating a valve, the first valve opening section having a shape for opening the valve at a low valve opening speed,
A cam having a second valve opening section continuous to the first valve opening section, the second valve opening section having a shape of opening at a valve opening speed higher than the valve opening speed of the first valve opening section. A cam that starts opening the valve in the first opening section when the valve clearance is within the proper range, and starts opening the valve in the second opening section when the valve clearance is outside the proper range. And a detection means for detecting a collision sound between the cam and the valve and determining whether or not the valve clearance is within an appropriate range based on the intensity of the detected collision sound. apparatus.