JP3643966B2 - Engine valve momentum measurement device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus capable of measuring the momentum of an engine valve incorporated in a valve mechanism of an internal combustion engine in an actual engine firing state.
[0002]
[Prior art]
In order to increase the output of the engine, it is effective to increase the allowable rotational speed of the engine. However, the increase in the allowable rotational speed is naturally limited due to the problem of followability of the valve operating system parts to the cam.
That is, the opening / closing motion of the engine valve is preset by the profile of the cam. If the engine valve operates according to the profile, gas exchange in the combustion chamber is smoothly performed, and the engine performance is improved.
[0003]
However, in reality, the higher the engine speed, the more difficult it is to operate the engine valve following the cam profile due to the inertial force due to the mass of the valve system components. Performance decreases.
[0004]
From this point of view, when the specifications of the valve system components are changed, the actual momentum of the engine valve is measured, and the valve system parts are evaluated based on the motion characteristics. In some cases, the follow-up performance to the cam is investigated.
[0005]
This measurement is usually performed by detecting the movement of an engine valve or a spring retainer fixed to the engine valve with a sensor.
At this time, the rocker arm type valve mechanism where the shaft end of the engine valve and the spring retainer are exposed can be measured without any trouble, but in the direct acting type valve mechanism, the shaft end of the engine valve and Because the spring retainer is located in the cup-shaped tappet, it is very difficult to detect their movement directly.
[0006]
Therefore, conventionally, the piston and connecting rod are removed from the cylinder block of the engine, a non-contact type displacement sensor is provided directly under the engine valve in the cylinder, and the engine placed on the table is motored, The displacement of the engine valve is measured by operating only the valve system.
[0007]
[Problems to be solved by the invention]
The above-mentioned measurement by motoring does not measure the actual movement of the valve when the engine is in the firing operation. Therefore, the effect of the combustion pressure in the cylinder on the movement of the engine valve is accurately measured. Cannot be measured.
[0008]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an engine valve momentum measuring device capable of measuring an actual movement of an engine valve with high accuracy.
[0009]
[Means for Solving the Problems]
According to the present invention, the above problem is solved as follows.
(1) A spring retainer is fastened to the end of the engine valve that is slidably supported by the cylinder head and protrudes from the cylinder head. A coiled valve is placed between the spring retainer and the cylinder head. An engine valve momentum measuring device for use in a valve operating mechanism in which a spring is contracted so as to surround a shaft portion of the engine valve, wherein an annular formed between the shaft portion of the engine valve and the valve spring A cylindrical bobbin formed by winding a coil made of primary and secondary on the outer peripheral surface of the space and concealing the periphery of the coil with a magnetic shield cylinder made of SUS304, which is a nonmagnetic material, A differential transformer type displacement consisting of a cylindrical core made of a non-magnetic metal material that can move up and down in the bobbin and that generates eddy currents The capacitors, the bobbin immobile member of the cylinder head side, and the upper end portion of the core is provided by fixing to each of the spring retainer.
[0010]
( 2 ) In the above item ( 1 ) , the core is formed of aluminum or copper.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a main part of a direct acting valve mechanism to which the present invention is applied.
[0012]
The shaft portion (1b) of the engine valve (1) is guided by a valve guide (10) press-fitted into the cylinder head (9) so as to be slidable in the vertical direction. A spring retainer (3) is attached through a half cylindrical cotter (2). Between the spring retainer (3) and the washer (11) placed on the upper surface of the cylinder head (9), a coiled valve spring (12) is provided in a contracted manner.
[0013]
The valve spring (12) is substantially coaxial with the shaft (1b) of the engine valve (1), and is disposed with a slight gap so as to surround the valve guide (10) and the shaft (1b). ing.
(13) is a lip seal that is fitted on the upper end of the valve guide (10), and prevents contact with the outer peripheral surface of the shaft (1b), thereby preventing excessive oil drop.
[0014]
The upper end of the shaft (1b) of the engine valve (1) is fitted with a cylindrical tappet (4) so as to cover the spring retainer (3), and the upper surface of the tappet (4). A cam (not shown) is in contact with the shim (5) fitted in the recess. When this cam rotates, the engine valve (1) is pushed down against the force of the valve spring (12) to open and close.
[0015]
In an annular space formed between the shaft portion (1b) and valve guide (10) of the engine valve (1) and the valve spring (12), a differential transformer type displacement sensor (14) is provided. It is assembled so as to surround the engine valve (1).
[0016]
The displacement sensor (14) comprises a bobbin (16) having a sensor coil (15) wound around an outer peripheral surface, and a cylindrical core (17) whose outer diameter is slightly smaller than the inner diameter of the bobbin (16). The bobbin (16) is fixed concentrically with the engine valve (1) by press-fitting a thick seat portion (16a) at the lower end into the outer peripheral surface of the upper end portion of the valve guide (10). The core (17) is held concentrically with the bobbin (16) by embedding and fixing the upper end of the core to the lower surface of the spring retainer (3), and the lower end of the core (17) is not connected to the engine valve (1). It is located in the bobbin (16) when it is in operation (when the valve is closed).
[0017]
When the spring retainer (3) moves up and down integrally with the opening and closing movement of the engine valve (1), the core (17) is disposed on the inner surface of the bobbin (16) as shown by the imaginary line in FIG. A slight gap is formed between them to enter.
[0018]
The bobbin (16), the stainless steel material or bakelite and core (17), more aluminum or copper, are respectively formed.
In addition, the weight of the spring retainer (3) is reduced by the weight of the core (17), and the increase of the inertial mass due to the attachment of the core (17) is eliminated.
[0019]
(18) is a multi-core lead wire connected to the coil (15) and is led out of the valve spring (12) through a wiring groove (19) formed on the upper surface of the cylinder head (9). The unit is connected to a measuring instrument main body (not shown).
[0020]
(20) is a magnetic shield cylinder made of SUS304, which is a non-magnetic material , disposed in the space between the bobbin (16) and the valve spring (12) so as to surround the sensor coil (15). (20a) is fitted into the valve guide (10) and fixed by pressing the cylinder head (9) with the seat (16a) of the bobbin (16).
[0021]
As schematically shown in FIG. 2, the sensor coil (15) includes a primary coil (15a) and a secondary coil (15b) wound in close contact with the primary coil (15a), and a part of the secondary coil. Is provided outside as a dummy coil (15c) to constitute a separate type differential transformer. In this way, the total length of the bobbin (16) and the sensor coil (15) can be shortened.
[0022]
The separation-type differential transformer, for example, when excited by the high frequency of 100-300KH _Z, large output voltage by the eddy current effects upon the non-magnetic core (17) moves within the bobbin (16) of the sensor coil (15) Is obtained. Thereby, the momentum of the spring retainer (3), that is, the engine valve (1) integrated therewith can be measured with high accuracy.
[0023]
The Displacement sensor (14), because are a high-frequency-excited separation type differential transformer using dummy coil, even if the number of turns of the secondary coil (15b) is less high output can be obtained, therefore, the bobbin (16) can be reduced in size and can be accommodated in a slight gap between the engine valve (1) and the valve spring (12).
[0024]
In addition, since the sensor coil (15) is covered with a magnetic shield cylinder (20), the magnetic characteristics during excitation to the differential transformer are not affected by the valve spring (12) and are responsive. And the linearity of the output voltage becomes good, and even a slight behavior of the engine valve (1) can be accurately detected without error.
[0025]
Although the present invention can be effectively applied to a relatively small engine having a small storage space for the displacement sensor (14), a normal differential transformer type displacement sensor is used for a large engine having a large storage space. Sometimes.
In the embodiment, the magnetic shield cylinder (20) is a separate body, but it may be fixed to the bobbin (16) or formed integrally therewith.
In the embodiment, an example is shown in which the present invention is applied to a direct acting type valve operating mechanism, but it is needless to say that the present invention can also be applied to a rocker arm type valve operating mechanism.
[0026]
【The invention's effect】
According to the present invention, since the displacement sensor is provided in the gap between the engine valve and the valve spring, even if the direct acting type valve operating mechanism using the tappet is used, It becomes possible to accurately measure the actual momentum without hindrance.
[0027]
In addition, since the periphery of the coil wound around the bobbin is concealed by a magnetic shield cylinder made of SUS304, which is a non-magnetic material, the magnetic characteristics of the differential transformer are prevented from being affected by the valve spring, and the response and output are improved. The voltage linearity is good, and even slight behavior of the engine valve can be measured with high accuracy.
[Brief description of the drawings]
FIG. 1 is an enlarged longitudinal sectional front view of an essential part of a direct acting valve mechanism to which an embodiment of the present invention is applied.
FIG. 2 is a schematic diagram of a differential transformer.
[Explanation of symbols]
(1) Engine valve
(1b) Shaft
(2) Cotta
(3) Spring retainer
(4) Tappet
(5) Sim
(6) Cam
(7) Cylinder
(9) Cylinder head
(10) Valve guide
(11) Washer
(12) Valve spring
(13) Lip seal
(14) Displacement sensor
(15) Sensor coil
(16) Bobbin
(16a) Seat part
(17) Core
(18) Multi-core lead wire
(19) Wiring groove
(20) Magnetic shield tube
(20a) Bottom plate

Claims (2)

A spring retainer is fastened to the shaft end protruding from the cylinder head of the engine valve slidably held by the cylinder head, and a coiled valve spring is placed between the spring retainer and the cylinder head. An engine valve momentum measuring device used for a valve mechanism that is contracted so as to surround a shaft portion of the engine valve,
A coil composed of primary and secondary is wound around the outer circumferential surface in an annular space formed between the shaft portion of the engine valve and the valve spring, and the periphery of this coil is SUS304 which is a nonmagnetic material. A differential transformer type comprising a cylindrical bobbin concealed by a magnetic shield cylinder and a cylindrical core made of a nonmagnetic metal material capable of moving up and down in the bobbin and generating eddy currents The engine valve momentum measuring device according to claim 1, wherein the displacement sensor is provided by fixing the bobbin to the stationary member on the cylinder head side and the upper end of the core to the spring retainer. Core, according to claim 1 Symbol placement was formed of aluminum or copper engine valve motion measurement apparatus.

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