JP2000162093A - Measuring apparatus for displacement of engine valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a measuring apparatus by which the actual displacement of an engine valve can be measured with high accuracy without being affected by a valve spring by a method wherein a part of the shaft part of the engine valve which is formed of a nonmagnetic material is formed as a small-diameter shaft part and a core is installed integrally with the engine valve. SOLUTION: In a state that the primary coil of a sensor coil 12 is excited by a high-frequency voltage, a small-diameter shaft part 16 is moved downward inside a bobbin 10. Then, output electric power which is proportional to the displacement amount of the small-diameter part 16 is generated in its secondary coil due to the effect of an eddy current which flows in the surface layer part of the small-diameter shaft part 16. The output electric power is fetched by a measuring device at the outside by using a lead wire 13, and the displacement of a valve 1 is measured directly. In addition, since the smalldiameter shaft part 16 is used as the core of a differential transformer-type displacement sensor, the outside diameter of the bobbin 10 and that of the sensor coil 12 on its outer circumferential face can be made small. As a result, a large space can be formed between the sensor coil 12 and a valve spring 7, and there is no fear that a measuring error is generated even when the magnetic characteristic of the sensor coil 12 is changed due to the movement of the valve spring 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the displacement of an engine valve in a firing state by an actual engine.
The present invention relates to a measuring device capable of detecting accurately.

[0002]

2. Description of the Related Art When the specifications of the components of a valve train are changed, the actual displacement (momentum) of an engine valve (hereinafter abbreviated as "valve") is measured, and the valve train components are measured based on the movement characteristics. May be evaluated or the followability of the valve to the cam may be examined.

[0003] This measurement is usually performed by detecting the axial displacement of a valve or a valve operating component (such as a spring retainer) that moves integrally with the valve by a proximity sensor or the like. For direct-acting valve trains in which the shaft end and spring retainer are covered by a cap-shaped tappet, or for small engines with little space around the valve train, attach a proximity sensor, etc. It may be difficult to directly detect the displacement of the spring retainer.

[0004] Therefore, in the above-mentioned direct acting valve operating mechanism,
Remove the piston and connecting rod from the cylinder block, provide a proximity sensor, etc., directly below the valve in the cylinder, and operate the engine on a table (motoring) to measure the axial displacement of the valve from the front of the umbrella. ing.

[0005] Since the measurement by the operation on such a table does not measure the actual displacement while the engine is in the firing operation, the combustion pressure in the cylinder, the back pressure of the exhaust system, etc. The effect on the behavior of the valve cannot be measured accurately.

Accordingly, the applicant of the present application has developed a relatively small measuring position capable of measuring the actual displacement of the valve during the firing operation of the engine with high accuracy, and has already applied for a patent ( See JP-A-9-61302).

[0007]

In the measuring device of the prior application, a differential transformer type displacement sensor is provided in an annular space between a valve and a valve spring, and its primary and secondary coils are wound. The displacement of the valve is detected by moving the core fixed to the spring retainer up and down in the bobbin. However, the following danger may be considered. That is, since the cylindrical core that moves up and down in the bobbin is fixed to the spring retainer, it is difficult to reduce the outer diameter of the bobbin, and the outer diameter of the bobbin and the coil wound therearound may become large. It was inevitable.

Therefore, when mounted on a valve operating mechanism of a small engine, the periphery of the coil wound on the bobbin comes close to the iron valve spring, and the magnetic characteristics at the time of excitation change due to the movement of the valve spring. Measurement errors may occur. In addition, since an inertial force acts on the core and the core vibrates, it must be firmly fixed to the spring retainer, and the operation is troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and minimizes the outer diameter of a bobbin and a coil wound therearound by making the outer diameter of a core as small as possible. It is an object of the present invention to provide an engine valve displacement measuring device capable of measuring the actual displacement of a valve with high accuracy without error without being affected by a spring.

[0010]

According to the present invention, the above-mentioned problem is solved as follows. (1) Displacement of an engine valve held slidably up and down on a cylinder head is controlled by a primary coil and a secondary coil on an outer peripheral surface provided concentrically with the engine valve on the cylinder head.
A bobbin around which a sensor coil composed of a secondary coil is wound,
In a displacement measuring device for an engine valve, which is detected by a differential transformer type displacement sensor comprising a core moving up and down in the bobbin following the engine valve,
The core is provided integrally with the engine valve by forming a part of the shaft part of the engine valve made of a non-magnetic material into a small-diameter or large-diameter shaft part.

(2) The displacement of the engine valve held in the cylinder head so as to be slidable up and down is adjusted by one on the outer peripheral surface provided concentrically with the engine valve on the cylinder head.
An engine valve which is detected by a differential transformer type displacement sensor comprising a bobbin wound with a sensor coil composed of a secondary coil and a secondary coil, and a core moving up and down in the bobbin following the engine valve. In the displacement measuring device, the core is provided integrally with the engine valve by fixing a non-magnetic and conductive ring to a shaft portion of the engine valve.

(3) The displacement of the engine valve held in the cylinder head so as to be slidable up and down is reduced by 1 on the outer peripheral surface provided concentrically with the engine valve on the cylinder head.
An engine valve which is detected by a differential transformer type displacement sensor comprising a bobbin wound with a sensor coil composed of a secondary coil and a secondary coil, and a core moving up and down in the bobbin following the engine valve. In the displacement measuring device, a non-magnetic and conductive ring is fitted on a small-diameter shaft portion formed on a shaft portion of an engine valve made of a non-magnetic material so as to have the same diameter as the outer diameter of the shaft portion. By combining, it is provided integrally with the engine valve.

(4) The displacement of the engine valve held in the cylinder head so as to be slidable up and down is reduced by 1 on an outer peripheral surface provided concentrically with the engine valve on the cylinder head.
An engine valve which is detected by a differential transformer type displacement sensor comprising a bobbin wound with a sensor coil composed of a secondary coil and a secondary coil, and a core moving up and down in the bobbin following the engine valve. In the displacement measuring device, a non-magnetic and conductive ring is formed on the small-diameter shaft portion formed on the shaft portion of the engine valve made of a non-magnetic material so that the diameter is slightly smaller than the outer diameter of the shaft portion. By fitting, it is provided integrally with the engine valve.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the embodiment of the invention described in claim 1 is applied to a direct-acting type valve operating mechanism. A valve (1) made of austenitic heat-resistant steel which is a non-magnetic material is shown in FIG. The shaft portion (1a) is supported so as to be slidable up and down by a valve guide (3) press-fitted immediately above an open end of an intake or exhaust port (not shown) in the cylinder head (2).

In FIG. 1, the valve (1) shows a closed state. A spring retainer (4) is fixed to the upper end of the shaft (1a) via a pair of cotters (5). The spring retainer (4) and a washer (6) on the upper surface of the cylinder head (2). ), A valve spring (7) is contracted.

At the upper end of the shaft (1a) of the valve (1), a cylindrical tappet (8) having a closed top is provided with a spring retainer (4) and an upper end of a valve spring (7). It is fitted from above so as to cover it, and its cylindrical portion (8a) is fitted in a vertical guide hole (not shown) in the cylinder head (2) so as to be slidable up and down.

A cam (not shown) slides on the upper surface of the shim (9) fitted in the concave hole on the upper surface of the tappet (8), and the rotation of the cam causes the valve (1) to move the valve spring (7). )
And the opening and closing movement is performed.

In the vicinity of the press-fit portion of the valve guide (3) in the cylinder head (2) inside the valve spring (7),
An upward cylindrical bulge (2a) is formed, and on its upper surface,
The seat (10a) of the cylindrical bobbin (10) is
It is fixed by a plurality of bolts (11) concentrically with (1) and in such a manner that a required gap is formed between it and the outer peripheral surface of the shaft portion (1a).

The bobbin (10) is formed of an insulating material such as a synthetic resin (for example, bakelite) or ceramics, and has on its outer peripheral surface a primary coil wound in a single layer or a plurality of layers, and a primary coil wound around the primary coil. A sensor coil (12) composed of a secondary coil (both not shown) wound closely thereon is wound.

The multi-core lead wire (13) connected to the sensor coil (12) passes through a wiring groove (14) formed on the outer peripheral surface of the bulging portion (2a) and the upper surface of the cylinder head (2). It is led out of the valve spring (7), and its terminal is connected to a measuring instrument main body (not shown).

The bobbin (10) has a bobbin
A plurality of oil drain holes (15) opening inside and outside of (10) are formed to discharge the lubricating oil flowing into the bobbin (10) to the outside.

The shaft portion (1a) immediately below the spring retainer (4)
A small-diameter shaft portion (16) having a slightly smaller outer diameter is formed over a required length. By this small diameter shaft portion (16) and the bobbin (10) around which the sensor coil (12) is wound,
A high-frequency differential transformer type displacement sensor is configured, and the small-diameter shaft portion (16) has a short-circuit portion, that is, a function of a core for partially canceling out magnetic flux generated by the sensor coil (12).

When the valve (1) is closed, the lower end of the small-diameter shaft portion (16) is located at the upper end of the bobbin (10), and at this time, the output voltage from the sensor coil (12) becomes zero. It is better to be. In this way, the displacement in the valve opening direction can be easily measured with the time when the valve (1) is fully closed as a reference (displacement 0). The axial length of the small-diameter shaft portion (16) is such that the step at the upper end thereof does not enter the bobbin (10) even when the valve (1) is lifted to the maximum.

[0024] In the above embodiment, the primary coil of the sensor coil (12), while excited by a high frequency voltage of 100～300KH _Z, the small-diameter shaft portion (16) moves downward through the bobbin (10), Due to the eddy current effect (eddy current loss) flowing through the surface of the small-diameter shaft portion (16), an output power proportional to the displacement of the small-diameter shaft portion (16) is obtained in the secondary coil, which is connected to the lead wire (1).
By taking out to the external measuring instrument body by 3), the valve
(1) The displacement can be directly measured.

Since the small-diameter shaft portion (16) formed on the shaft portion (1a) of the valve (1) is used as the core of the differential transformer type displacement sensor, the bobbin (10) provided so as to surround that portion.
Needless to say, the outer diameter of the sensor coil (12) wound around the outer peripheral surface can be reduced.

As a result, a large space can be formed between the sensor coil (12) and the valve spring (7). The magnetic characteristics of the coil (12) are changed by the movement of the valve spring (7), and there is no possibility that a measurement error occurs.

Further, since the shaft portion (1a) of the valve (1) itself is used as a core, an inertial force acts on the core as in a conventional device in which the core is fixed to a spring retainer (4).
There is no fear of vibration or the like, and there is no problem in strength.

FIG. 2 shows a main part of an embodiment according to the second aspect of the present invention. In the following embodiment, the only difference from the above-described embodiment is the structure of the core of the shaft portion (1a), and the illustration of other members is omitted.

In this embodiment, the outer peripheral surface of the shaft portion (1a) which enters the bobbin (10) is made of a non-magnetic and highly conductive metal material such as aluminum or copper (both including alloys). A cylindrical short-circuit ring (17) is fixed by press-fitting (including shrink fitting and cold fitting). This short-circuit ring (17) has the same function as a core as described above. The vertical dimension of the short-circuit ring (17) is larger than the maximum lift of the valve (1).

In this embodiment, the same operation and effect as described above can be obtained. In addition, since the short-circuit ring (17) is made of a good conductive metal material having a small resistivity, the eddy current effect of the surface layer becomes large, and the output sensitivity can be increased.

FIG. 3 shows a main part of an embodiment according to the third aspect of the present invention. In this embodiment, a short-circuit ring made of the same material as that shown in FIG.
(18) is fitted so as to have the same diameter as the outer diameter of the shaft portion (1a), thereby having an action as a core of the differential transformer. The short-circuit ring (18) can be fixed by thermal spraying, overlaying, sputtering, brazing (welding) or the like.

Also in this embodiment, the displacement of the valve (1) can be directly measured by the eddy current effect flowing in the surface layer of the short-circuit ring (18). Also, since the outer diameter of the short-circuit ring (18) and the outer diameter of the shaft portion (1a) are equal, the valve
(1) can be assembled to the cylinder head (2) without any trouble.

FIG. 4 shows a main part of an embodiment of the present invention. In this embodiment, a short-circuit ring (19) made of the same material as the short-circuit ring (18) shown in FIG. 3 and having a slightly smaller outer diameter is attached to the small-diameter shaft portion (16) formed on the shaft portion (1a). Mated,
A step is formed between the shaft (1a) and the short-circuit ring (19). Also in this embodiment, the same operation and effect as described above can be obtained, and the eddy current effect (eddy current loss) becomes larger than that shown in FIG. 3 by forming the step with the short-circuit ring (19) having a small diameter. , Can increase the sensitivity.

The present invention is not limited to the above embodiment. In the above embodiment, the valve (1) is made of austenitic heat-resistant steel. However, the present invention can be applied to other non-magnetic materials, for example, valves made of titanium or aluminum alloy.

As in the embodiment shown in FIG. 2, when the non-magnetic and highly conductive short-circuit ring (17) is provided so as to have a diameter larger than the outer diameter of the shaft portion (1a), The material of the valve (1) does not necessarily need to be a non-magnetic material, but may be a valve using a martensitic heat-resistant steel or the like.

In each embodiment, the displacement sensor may be a separated high-frequency differential transformer as disclosed in Japanese Patent Application Laid-Open No. 9-61302 by the present applicant. )
The outer diameter of the bobbin (10) including the coil (12) can be made smaller.

As shown in FIG. 1, when forming a core integral with the shaft portion (1a), instead of using the small-diameter shaft portion (16) as in the embodiment, a part of the shaft portion has a large diameter. This portion may be used as a core as a shaft portion. At this time, if the engine valve (1) is assembled to the cylinder head (2) and then a large-diameter shaft is formed by thermal spraying or overlaying, the engine valve (1) will not be unable to be assembled.

The present invention can be applied to a rocker arm type valve operating mechanism in addition to the direct acting type valve operating mechanism.

[0039]

According to the first aspect of the present invention, since the core of the differential transformer type displacement sensor is provided integrally with the shaft of the engine valve, the bobbin and the sensor wound therearound are provided. The outer diameter of the coil can be reduced.
As a result, even when the valve is mounted on a small valve operating mechanism having a small space for mounting the displacement sensor, the magnetic characteristics are not changed by the influence of the valve spring, and the displacement of the engine valve can be measured with high accuracy.

(B) According to the second to fourth aspects of the present invention,
In addition to the effect of the above (a), the effect of eddy current flowing in the surface layer of the ring becomes large, so that the output sensitivity is increased and there is no possibility of causing a measurement error.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional front view showing a direct-acting type valve operating mechanism to which an embodiment of the present invention is applied.

FIG. 2 is a longitudinal sectional front view of a main part showing an embodiment of the invention described in claim 2;

FIG. 3 is a longitudinal sectional front view of a main part showing an embodiment of the invention described in claim 3;

FIG. 4 is a longitudinal sectional front view of an essential part showing an embodiment of the invention described in claim 4;

[Explanation of symbols]

 (1) Engine valve (1a) Shaft (2) Cylinder head (2a) Swelling part (3) Valve guide (4) Spring retainer (5) Cotta (6) Washer (7) Valve spring (8) Tappet (9) ) Shim (10) Bobbin (11) Bolt (12) Sensor coil (13) Multi-core lead wire (14) Wiring groove (15) Oil drain hole (16) Small diameter shaft (17) (18) (19) Short-circuit ring

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haruki Kobayashi F-term (reference) 2F0ZA AA15 BB01 CC40 in 1--22, Engy 行, Fujisawa-shi, Kanagawa, Japan

Claims (4)

[Claims] 1. A sensor coil comprising a primary coil and a secondary coil on an outer peripheral surface provided concentrically with an engine valve on a cylinder head, the displacement of the engine valve held in a cylinder head so as to be slidable up and down. In a displacement measuring device for an engine valve configured to be detected by a differential transformer-type displacement sensor including a bobbin wound with a core and a core that moves up and down in the bobbin following the engine valve, the core includes: An engine valve displacement measuring device, wherein a part of a shaft portion of an engine valve formed of a non-magnetic material is formed integrally with the engine valve by forming a small diameter or a large diameter shaft portion. 2. A sensor coil comprising a primary coil and a secondary coil on an outer peripheral surface provided concentrically with an engine valve on a cylinder head, the displacement of an engine valve held slidably up and down on a cylinder head. In a displacement measuring device for an engine valve configured to be detected by a differential transformer-type displacement sensor including a bobbin wound with a core and a core that moves up and down in the bobbin following the engine valve, the core includes: An engine valve displacement measuring device, which is provided integrally with an engine valve by fixing a non-magnetic and conductive ring to a shaft portion of the engine valve. 3. A sensor coil comprising a primary coil and a secondary coil on an outer peripheral surface provided concentrically with an engine valve on a cylinder head and displaced by an engine valve held slidably up and down on a cylinder head. In a displacement measuring device for an engine valve configured to be detected by a differential transformer-type displacement sensor including a bobbin wound with a core and a core that moves up and down in the bobbin following the engine valve, the core includes: A non-magnetic and conductive ring is attached to the small diameter shaft formed on the shaft of the engine valve made of non-magnetic material.
An engine valve displacement measuring device, which is provided integrally with an engine valve by being fitted so as to have the same diameter as the outer diameter of a shaft portion. 4. A sensor coil comprising a primary coil and a secondary coil on an outer peripheral surface provided concentrically with an engine valve on a cylinder head and displaced by an engine valve held vertically slidably on a cylinder head. In a displacement measuring device for an engine valve configured to be detected by a differential transformer-type displacement sensor including a bobbin wound with a core and a core that moves up and down in the bobbin following the engine valve, the core includes: A non-magnetic and conductive ring is attached to the small diameter shaft formed on the shaft of the engine valve made of non-magnetic material.
An engine valve displacement measuring device, which is provided integrally with an engine valve by being fitted so as to have a slightly smaller diameter than the outer diameter of the shaft portion.