JP5014183B2 - Engine valve displacement measuring device and engine equipped with the same - Google Patents

Description

  The present invention relates to a displacement measuring device capable of measuring a displacement of an engine valve incorporated in a valve mechanism of an engine in a firing state by an actual engine, and an engine including the same.

Increasing the engine's permissible rotational speed is an effective way to increase the engine's output, but the increase in the permissible rotational speed is naturally limited due to the problem of followability of the valve system parts to the cam. .
In other words, the opening and closing movement of the engine valve is preset by the cam profile, and if the engine valve always follows the profile, the maximum engine speed can be increased and the engine output performance is improved. To do.

  However, in practice, 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. Output performance cannot be secured.

  From this point of view, when the specifications of the valve system components are changed, the actual displacement of the engine valve is measured, and the valve system parts are evaluated based on the displacement characteristics. In some cases, the follow-up performance to the cam is investigated.

Applicants of the present application have developed a displacement measuring device that incorporates a differential transformer type displacement sensor into the valve mechanism of the engine and can accurately measure the displacement of the engine valve in the firing state. (See Patent Document 1).
Japanese Patent No. 3634966

  In the engine valve displacement measuring device described in the above-mentioned patent document, a bobbin having a sensor coil wound around an outer peripheral surface and a core that enters the bobbin are included in the engine valve, the valve spring, and the displacement sensor. Therefore, it is difficult to incorporate a displacement sensor into a small engine having a small inner diameter of a valve spring.

  That is, if a displacement sensor is to be incorporated in a small engine, the number of primary and secondary sensor coils wound around the outer peripheral surface of the bobbin, the coil diameter, the movement stroke of the core, etc. are limited, There is a problem that a measurement error occurs due to the sensor coil being close to the valve spring and the magnetic characteristics of the differential transformer being influenced by the valve spring.

  In addition, when the bobbin around which the sensor coil is wound is housed inside the valve spring, it is necessary to process the cylinder head in order to lead the lead wire wired to the outside of the valve spring. There is also a problem that the displacement measuring device cannot be easily incorporated.

  The present invention has been made in view of the above problems, can be easily incorporated into a small engine, can measure the displacement of an engine valve with high accuracy, and does not substantially process an existing engine, An object of the present invention is to provide an engine valve displacement measuring device that can be easily incorporated, and an engine including the same.

According to the present invention, the above problem is solved as follows.
(1) A spring retainer is fastened to the shaft end protruding from the cylinder head of the engine valve that is slidably supported by the cylinder head up and down, and is coiled between the opposing surfaces of the spring retainer and the cylinder head. An engine valve displacement measuring device used in a valve operating mechanism in which a valve spring of the engine valve is contracted so as to surround the shaft portion of the engine valve, and a bobbin having a sensor coil wound around an outer peripheral surface thereof, A displacement sensor comprising a cylindrical core that can move up and down along the inner peripheral surface of the bobbin, a bobbin or a support cylinder that supports the displacement sensor on the cylinder head, and an upper end of the core on the outside of the valve spring Enclose the valve spring by fixing it to the spring retainer so as to be concentric with the engine valve. Provided.

(2) In the above item (1), the lower end of the valve spring, in which an inward annular piece is connected to the lower end of the bobbin or the supporting cylinder that supports the bobbin, and the inward annular piece is provided on the upper surface of the cylinder head, The bobbin is fixed to the cylinder head by fitting into the annular groove to be held and applying a strong pressure by contacting the lower end of the valve spring to the upper surface of the inward annular piece.

(3) In the above item (1) or (2), the core is formed of a nonmagnetic metal material having a property of generating eddy current, and the sensor coil is composed of a primary coil and a secondary coil. Thus, the displacement sensor is an eddy current effect type differential transformer.

(4) In the above item (3), the displacement sensor is a separation-type differential transformer by providing a dummy coil external to the sensor coil.

(5) In the above item (3) or (4), the displacement sensor is a high-frequency excitation type differential transformer.

(6) In any one of the above items (3) to (5), the core is formed of aluminum.

(7) In any one of the above items (1) to (6), at least one of the outer peripheral surface of the sensor coil and the inner peripheral surface side of the bobbin between the core and the valve spring is a shield made of a nonmagnetic metal material. Cover with a cylinder.

(8) In any one of the above items (1) to (6), at least one of the outer peripheral surface of the sensor coil and the inner peripheral surface side of the bobbin between the core and the valve spring is made of a highly permeable metal material. Cover with a shield tube.

(9) In the above item (7) or (8), the shield cylinder is provided integrally with the support cylinder that supports the bobbin.

(10) An engine of the present invention includes the engine valve displacement measuring device according to any one of the above items (1) to (9).

According to the first aspect of the present invention, since the displacement sensor is provided so as to surround the valve spring, the displacement measuring device can be easily incorporated into a small engine.
Further, if the displacement sensor is provided outside the valve spring, the number of turns of the sensor coil, the coil diameter, the movement stroke of the core, etc. can be increased, so that even if the number of turns of the primary and secondary coils is small, the linearity A certain output voltage can be obtained, and the displacement of the engine valve can be accurately measured without error.
In addition, since the number of turns of the coil can be reduced and the thickness thereof can be reduced, the installation space for the displacement measuring device can be minimized.
Furthermore, if the displacement sensor is provided outside the valve spring, the installation space in the vertical direction can be afforded, so that the measurement length can be increased.

  According to the second aspect of the present invention, the bobbin or the support body that supports the bobbin is provided in the annular concave groove that is provided on the upper surface of the cylinder head and that holds the lower end of the valve spring by using the spring force of the valve spring. Since it is fixed, there is no need to use a fixing means for fixing the bobbin to the cylinder head or to process the cylinder head, and the displacement measuring device can be easily incorporated into an existing engine.

  According to the third aspect of the present invention, since the displacement sensor is an eddy current effect type differential transformer, the core can be made thin and light, and the inertial mass can be reduced. The risk of impacting is reduced.

  According to the invention described in claim 4, since the displacement sensor is a separation type differential transformer, the vertical dimension of the bobbin and the sensor coil wound around the bobbin is reduced, and the displacement sensor can be downsized.

  According to the fifth aspect of the invention, since the displacement sensor is a high-frequency excitation type differential transformer, an output voltage with excellent linearity and good linearity can be obtained even if the number of turns of the sensor coil is small. The displacement of the engine valve can be accurately measured without error.

According to the sixth aspect of the present invention, when the core is made of aluminum, eddy current is likely to be generated on the surface layer, so that the output voltage from the sensor coil is increased and the displacement of the engine valve can be measured more accurately. .
In addition, since the inertial mass of the core fixed to the spring retainer is reduced, the risk of affecting the behavior of the engine valve and the measurement of displacement is reduced.

  According to the seventh aspect of the present invention, an eddy current is generated in the shield cylinder made of a non-magnetic metal material by the magnetic flux of the sensor coil, and the magnetic characteristics of the sensor coil are that of the tappet in the valve spring or the direct acting valve mechanism. Since it is less susceptible to influence, even a slight behavior of the engine valve can be measured with high accuracy.

  According to the eighth aspect of the invention, since most of the magnetic flux of the sensor coil is attracted to the shield cylinder made of a highly permeable metal material, the magnetic characteristic of the sensor coil is a tappet in a valve spring or a direct acting valve mechanism. This makes it possible to measure even a slight behavior of the engine valve with high accuracy.

  According to the ninth aspect of the present invention, a fixing means for fixing the shield cylinder is not necessary, and the bobbin around which the sensor coil is wound and the shield cylinder are assembled in a unit into the support cylinder, and only the support cylinder is obtained. Since it only has to be fixed to the cylinder head, the number of assembling steps can be reduced and there is no possibility of causing an assembling error.

  According to the tenth aspect of the present invention, even in a small engine, the actual displacement amount of the engine valve during the firing operation can be accurately measured from the outside by the displacement measuring device incorporated therein.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a direct-acting valve operating mechanism in an engine provided with a first embodiment of a displacement measuring device of the present invention.

  A shaft portion 1a of the engine valve 1 is fitted to a valve guide 3 press-fitted into the cylinder head 2 of the engine so as to be slidable up and down, and in an annular groove 4 formed on the outer peripheral surface of the upper end portion of the shaft portion 1a. A spring retainer 6 made of, for example, an aluminum alloy is substantially fixed integrally with the engine valve 1 via a pair of half-cylindrical cotters 5 and 5.

  On the upper surface of the cylinder head 2, an annular groove 7 is formed concentrically with the engine valve 1. The annular groove 7 opens upward to restrict the lower end of the valve spring 9 from moving in the radial direction. A coil-shaped valve spring 9 is concentric with the washer 8 inserted into the spring 7 and the spring receiving flange 6a on the outer periphery of the spring retainer 6 so as to surround the shaft 1a of the engine valve 1. It has been reduced.

  At the upper end of the valve guide 3 that slightly protrudes from the upper surface of the cylinder head 2, a lip seal 10 that prevents excessive oil drop is provided so that the inner peripheral surface of the upper end contacts the outer peripheral surface of the shaft portion 1a. Is press-fitted.

  At the upper end of the shaft portion 1a of the engine valve 1, a top cylindrical tappet 11 made of, for example, an aluminum alloy covers the spring retainer 6 and protrudes at the lower center of the lower projection 11a. The cylindrical skirt portion 11b of the tappet 11 is slidable up and down in the fitting hole 13 of the guide portion 12 integral with the cylinder head 2. It is mated.

  A cam 14 is in contact with the upper surface of the tappet 11, and when the cam 14 rotates, the engine valve 1 is pushed down against the spring force of the valve spring 9 through the tappet 11, and is opened and closed. (See FIG. 2).

  In an annular space formed between the outer peripheral surface of the valve spring 9 and the inner surface of the fitting hole 13 of the guide portion 12 and the skirt portion 11b of the tappet 11 in the cylinder head 2, a differential transformer type displacement sensor 15 is provided. Is incorporated.

  The displacement sensor 15 includes a cylindrical bobbin 17 having a sensor coil 16 wound around an outer peripheral surface thereof, and a cylindrical core 18 having an outer diameter slightly smaller than the inner diameter of the bobbin 17. Is press-fitted from below so as to be concentric with the engine valve 1 in a small diameter portion 6b formed in the lower half portion of the outer peripheral surface of the spring receiving flange portion 6a of the spring retainer 6.

The bobbin 17 is substantially fixed to the upper surface of the cylinder head 2 as follows.
In the annular groove 7 on the upper surface of the cylinder head 2, an inward annular piece 19 a connected to the lower end of a support cylinder 19 having a diameter capable of covering the valve spring 9 is positioned below the washer 8. The support cylinder 19 is fixed concentrically to the upper surface of the cylinder head 2 concentrically with the engine valve 1 by fitting the inner annular piece 19a downward with the spring force of the valve spring 9. The washer 8 may be omitted, and the lower end of the valve spring 9 may be directly pressed against the upper surface of the inward annular piece 19a.

  A shield cylinder 20 that is slightly larger in diameter than the support cylinder 19 and can cover the outer peripheral surface of the sensor coil 16 is integrally connected to the upper end of the support cylinder 19, and the bobbin 17 is connected to the engine inside the shield cylinder 20. It is fixed together with the sensor coil 16 so as to be concentric with the valve 1 and the core 18.

When the engine valve 1 is not in operation (when the valve is closed), the lower end portion of the core 18 is located in the upper end portion of the bobbin 17, and when the engine valve 1 is pushed down to the maximum lift from this position, it is integrated with the spring retainer 6. As shown in FIG. 2, the core 18 forming the inner part enters the bobbin 17 to the lower end portion while forming a slight gap with the inner peripheral surface thereof.
Further, the skirt portion 11 b of the tappet 11 descends to the position surrounding the upper half of the sensor coil 16 on the outer side close to the outer peripheral surface of the shield tube 20.

The above-described bobbin 17 is formed of, for example, heat-resistant bakelite or polyimide resin, and the core 18 is formed of a nonmagnetic metal material having a thickness of about 0.5 mm to 2 mm, such as aluminum or copper. .
The spring retainer 6 is lightened by the weight of the core 18 to eliminate an increase in inertial mass due to the attachment of the core 18.

  The support cylinder 19 and the shield cylinder 20 are made by deep drawing a non-magnetic metal material such as austenitic stainless steel (SUS304) or copper, or a highly permeable metal material such as permalloy or amorphous. It is integrally formed.

  The sensor coil 16 wound around the bobbin 17 comprises a primary coil 16a and a secondary coil 16b wound in layers as schematically shown in FIG. 3, and the sensor coil 16 is tuned to it. A dummy coil (reference coil) 21 provided externally is connected. Thus, a separation type differential transformer is configured. Thus, when the dummy coil 21 that synchronizes with the sensor coil 16 is provided, the vertical dimension of the bobbin 17 and the sensor coil 16 wound around the bobbin 17 can be shortened.

  As shown in FIG. 1, the multi-core lead wire 22 connected to the sensor coil 16 is led out through a rocker cover (not shown) of the engine and is connected to a measuring instrument body (not shown).

Between the sensor coil 16 and the dummy coil 21 in the separation-type differential transformer, for example by applying a high frequency alternating current of 100-300KH _Z, is excited them, core 18 made of a nonmagnetic metallic material, the sensor coil 16 is wound The eddy current effect when moving in the rotated bobbin 17, that is, the eddy current flowing through the core 18 increases or decreases according to the moving stroke, and at that time, eddy current loss is generated proportionally, The output voltage of the sensor coil 16 also changes proportionally.
The change in the output voltage of the sensor coil 16 is compared with the reference voltage of the dummy coil 21 and converted into a displacement amount, whereby the spring retainer 6, that is, the engine valve 1 that is substantially integrated with the change in the vertical direction. The amount of displacement (valve lift) can be measured.

  At this time, it is conceivable that the skirt portion 11b of the tappet 11 descends so as to cover the sensor coil 16, and this adversely affects the magnetic characteristics of the displacement sensor 15. Therefore, the responsiveness of the displacement sensor 15 and the linearity of the output voltage are not affected by the skirt portion 11b of the tappet 11 or the guide portion 12 of the cylinder head 2 that is close to the sensor coil 16. As a result, the slight behavior of the engine valve 1 can be accurately measured without error.

When a non-magnetic metal material such as aluminum is used for the shield cylinder 20, an eddy current is generated in the shield cylinder 20 due to the magnetic flux of the sensor coil 16, and the magnetic flux diffuses to the skirt portion 11 b side of the tappet 11. Is prevented.
On the other hand, when a highly permeable metal material such as permalloy is used for the shield cylinder 20, most of the magnetic flux of the sensor coil 16 is attracted to the shield cylinder 20, so that the magnetic flux is applied to the skirt portion 11b side of the tappet 11 as described above. It is prevented from spreading.
By such an action of the shield cylinder 20, the magnetic characteristic of the displacement sensor 15 is prevented from being influenced by the tappet 11, and the displacement of the engine valve 1 can be measured accurately.

  FIG. 4 shows a valve operating mechanism provided with the second embodiment of the displacement measuring apparatus of the present invention. In addition, the same code | symbol is attached | subjected to the member similar to the said embodiment, and detailed description is abbreviate | omitted.

In the displacement measuring apparatus according to the second embodiment, the second shield cylinder 23 made of the same material as the shield cylinder 20 is disposed in the annular space between the valve spring 9 and the core 18, and the inner peripheral surface side of the bobbin 17 is disposed. It is provided to cover.
That is, the inward annular piece 23 a provided continuously with the lower end of the shield cylinder 23 is sandwiched between the washer 8 and the inward annular piece 19 a of the support cylinder 19, and is held by the spring force of the valve spring 9. The cylinder 23 is fixed concentrically with the engine valve 1 so as to be close to the outer peripheral surface of the valve spring 9 and the inner peripheral surface of the core 18.

As described above, when the second shield cylinder 23 covering the inner peripheral surface side of the bobbin 17 is provided between the valve spring 9 and the core 18, the magnetic characteristics of the displacement sensor 15 are reduced by the action similar to the above. Since it becomes difficult to receive the influence of the spring 9, the displacement amount of the engine valve 1 can be measured with higher accuracy than in the first embodiment.
The second shield cylinder 23 may be integrated by welding to the inner surface of the support cylinder 19 or may be integrally formed with the support cylinder 19.

FIG. 5 shows a valve operating mechanism provided with a third embodiment of the displacement measuring apparatus of the present invention.
In the third embodiment, a diameter-enlarged portion 19 b is connected to the upper end portion of the support cylinder 19, and the downward cylindrical portion 17 a is formed at the lower end of the bobbin 17 that has a vertical dimension corresponding to the maximum descending stroke of the core 18. The downward cylinder portion 17a is press-fitted to the enlarged diameter portion 19b, and the outer peripheral surface of the sensor coil 16 is covered with a shield cylinder 24 that is a separate body from the support cylinder 19.

As described above, when the shield cylinder 24 is separated from the support cylinder 19 and the support cylinder 19 is positioned below the sensor coil 16, the magnetic characteristics of the displacement sensor 15 are less affected by the support cylinder 19, and high accuracy is achieved. Can be measured.
Moreover, the support cylinder 19 can be manufactured with an inexpensive material, and the selection range of the material is expanded.

FIG. 6 shows a valve operating mechanism provided with the fourth embodiment of the displacement measuring apparatus of the present invention.
In the fourth embodiment, a support cylinder 19 is connected to the lower end of the bobbin 17, and the outer peripheral surface of the sensor coil 16 is covered with a separate shield cylinder 25.
In this way, it is not necessary to form the bobbin 17 and the support cylinder 19 separately, so that the cost can be reduced.
In addition, although illustration is abbreviate | omitted, also in 3rd and 4th embodiment, you may provide the 2nd shield cylinder 23 similar to 2nd Embodiment.

  As described above, in each of the displacement measuring devices of the above-described embodiment, the differential transformer type displacement sensor 15 is provided outside the valve spring 9 so as to surround it. It can be easily incorporated into small and small engines.

  In addition, since the displacement sensor 15 is a high-frequency excitation type separation type differential transformer using the dummy coil 21, a high output can be obtained. Accordingly, the bobbin 17 can be reduced in size by minimizing the number of turns of the sensor coil 16 and can be easily accommodated in a small annular space between the valve spring 9 and the guide portion 12 of the cylinder head 2.

  If the displacement sensor 15 is provided outside the valve spring 9, the number of turns of the sensor coil 16 and the stroke of the core 18 can be increased, so that the output from the sensor coil 16 can be increased and the displacement of the engine valve 1 can be increased. Can be measured accurately without error.

  The present invention can also be applied to a rocker arm type valve mechanism that does not use the tappet 11. However, when applied to this rocker arm type valve mechanism, the outside of the valve spring 9 is largely open, so that the sensor By increasing the number of turns of the coil 16, the displacement of the engine valve 1 can be measured with higher accuracy.

  The bobbin 17 around which the sensor coil 16 is wound is provided on a support cylinder 19 fixed to the upper surface of the cylinder head 2 by the spring force outside the valve spring 9, so that the bobbin 17 is fixed to the cylinder head 2. Since the fixing means and processing to be performed are unnecessary and the core 18 is only press-fitted to the small diameter portion 6b of the outer peripheral portion of the spring retainer 6, the displacement measuring device can be easily incorporated into an existing engine. it can.

  Moreover, the support cylinder 19 and the displacement sensor 15 are assembled in advance to form a unit, and the inward annular piece 19a at the lower end of the support cylinder 19 is simply fitted into the annular groove 7 formed on the upper surface of the cylinder head 2, Since it only needs to be pressed by the spring force of the valve spring 9, no assembly error occurs.

  In the above embodiment, the lower end portion of the support cylinder 19 or the bobbin 17 is fixed by the spring force of the valve spring 9. However, they may be fixed to the upper surface of the cylinder head 2 by fixing means such as screws. .

  When the present invention is applied to a rocker arm type valve operating mechanism, the outer shield cylinders 20, 24, 25 may be omitted and only the inner second shield cylinder 23 may be provided.

  In the above embodiment, the core 18 is made of a non-magnetic metal material that easily generates eddy currents, and eddy current loss is caused to measure the displacement of the engine valve 1. Sensors can also be used. In this case, the core 18 may be made of a highly magnetic material such as iron.

It is an enlarged vertical front view of the principal part of the direct acting valve mechanism to which the first embodiment of the present invention is applied. Similarly, it is an enlarged vertical front view in a state where it is pushed to the maximum by a cam. Similarly, it is a schematic longitudinal cross-sectional view of a differential transformer. It is an expansion vertical front view of the principal part of the direct acting type valve mechanism to which the 2nd Embodiment of this invention is applied. Similarly, it is an enlarged vertical front view of the main part of the direct acting valve mechanism to which the third embodiment is applied. Similarly, it is an enlarged longitudinal sectional front view of a main part of a direct acting type valve operating mechanism to which the fourth embodiment is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine valve 1a Shaft part 2 Cylinder head 3 Valve guide 4 Annular groove 5 Cotta 6 Spring retainer 6a Spring receiving flange part 6b Small diameter part 7 Annular groove 8 Washer 9 Valve spring 10 Lip seal 11 Tappet 11a Downward projecting part 11b Skirt part DESCRIPTION OF SYMBOLS 12 Guide part 13 Fitting hole 14 Cam 15 Displacement sensor 16 Sensor coil 16a Primary coil 16b Secondary coil 17 Bobbin 17a Downward cylinder part 18 Core 19 Supporting cylinder 19a Inward annular piece 19b Expanding part 20 Shield cylinder 21 Dummy coil 22 Multi-core lead wire 23 Second shield cylinder 23a Inward annular piece 24 Shield cylinder 25 Shield cylinder

Claims (10)

A spring retainer is fastened to the shaft end protruding from the cylinder head of the engine valve that is slidably held up and down by the cylinder head, and a coiled valve spring is provided between the opposing surfaces of the spring retainer and the cylinder head. Is a displacement measuring device for an engine valve used in a valve operating mechanism that is contracted so as to surround the shaft portion of the engine valve,
A displacement sensor consisting of a bobbin having a sensor coil wound around its outer peripheral surface and a cylindrical core that can move up and down along the inner peripheral surface of this bobbin, and a bobbin or a support cylinder that supports it as a cylinder head. And measuring the displacement of the engine valve by surrounding the valve spring by fixing the upper end of the core to the spring retainer outside the valve spring so as to be concentric with the engine valve. apparatus.   An inward annular piece is connected to the lower end of the bobbin or the support cylinder that supports the bobbin, and this inward annular piece is fitted into an annular groove that is provided on the upper surface of the cylinder head and holds the lower end of the valve spring. 2. A displacement measuring device for an engine valve according to claim 1, wherein the bobbin is fixed to the cylinder head by abutting the lower end of the valve spring against the upper surface of the inward annular piece and applying a strong pressure.   By forming the core from a non-magnetic metal material having the property of generating eddy currents, and the sensor coil is composed of a primary coil and a secondary coil, the displacement sensor can be made to differ from the eddy current effect type. The engine valve displacement measuring device according to claim 1 or 2, wherein the device is a dynamic transformer.   4. The engine valve displacement measuring device according to claim 3, wherein the displacement sensor is formed as a separate type differential transformer by providing a dummy coil in synchronization with the sensor coil.   5. A displacement measuring device for an engine valve according to claim 3, wherein the displacement sensor is a high frequency excitation type differential transformer.   The displacement measuring device for an engine valve according to any one of claims 3 to 5, wherein the core is made of aluminum.   The engine according to any one of claims 1 to 6, wherein at least one of the outer peripheral surface of the sensor coil and the inner peripheral surface side of the bobbin between the core and the valve spring is covered with a shield cylinder made of a nonmagnetic metal material. Valve displacement measuring device.   The outer peripheral surface of the sensor coil and at least one of the inner peripheral surface side of the bobbin between the core and the valve spring are covered with a shield cylinder made of a highly permeable metal material. Engine valve displacement measuring device.   The engine valve displacement measuring device according to claim 7 or 8, wherein the shield tube is integrally provided on a support tube that supports the bobbin.   An engine comprising the displacement measuring device for an engine valve according to any one of claims 1 to 9.

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