JP2011069230A - Variable cam phase internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable cam phase internal combustion engine in which outer dimensions in a camshaft direction of the engine are suppressed. <P>SOLUTION: A solenoid body 52 keeps a projection 62 containing a projecting tapered surface 62a at the rear end center thereof while holding a push rod 53 slidable through a bearing 61. The bearing 61 is press fitted in the projection 62 and has a rear end flush with the rear end of the projection 62. The solenoid body 52 contains a bearing holding the push rod 53 on the front end side in addition than the bearing 61 press fitted in the projection 62. A projecting amount L2 of the projection 62 is set smaller than a diameter D of the push rod 53 (refer to Fig.3). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cam phase variable internal combustion engine in which a cam phase is continuously variably controlled, and more particularly, to a technique for suppressing an external dimension in a cam shaft direction of an engine.

  Many 4-cycle engines (hereinafter simply referred to as engines) are equipped with various variable valve mechanisms to improve output and fuel consumption, reduce harmful exhaust gas components, and the like. As a variable valve mechanism, instead of switching a plurality of existing cams (for example, a low speed type cam and a high speed type cam), the cam phase and In recent years, the valve lift and the individual individually continuously variable control have become mainstream. As a valve timing control device (Variable Timing Control Device: hereinafter referred to as VTC) used for variable control of the cam phase, a vane type hydraulic actuator (VTC actuator) is attached to the end of the camshaft, and the engine body Generally, a spool valve (hydraulic circuit switching valve) held at the axis of a VTC actuator is driven by a linear solenoid fixed to a side member (cylinder head or cam cover). (See Patent Document 1).

JP 2005-264950 A

  In the conventional VTC described above, the linear solenoid is fixed to the engine body side member, while the VTC actuator rotates integrally with the camshaft. Therefore, it is necessary to provide a predetermined gap between the linear solenoid and the VTC actuator. Further, since the linear solenoid satisfies the push rod holding length, thrust (pressing force), and stroke required values, the axial dimension cannot be made very small. Also, the VTC actuator cannot satisfy the required value of the cam phase change speed and holding performance, and the axial dimension cannot be reduced too much due to the relationship of the fastening bolt to the camshaft. And when it designed so that each of these conditions might be met, there existed a problem that the external dimension in the cam shaft direction of an engine became large and the mounting property to an engine room fell.

  Patent Document 1 discloses a technique for installing a linear solenoid at a site away from a VTC actuator by driving a spool valve via a link mechanism in order to suppress the outer dimension in the cam shaft direction of the engine. . However, when this method is adopted, the increase in the number of parts and the manufacturing cost due to the addition of the link mechanism, the decrease in control accuracy due to the bending of the link, and the like cannot be avoided.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a cam phase variable internal combustion engine in which the outer dimension in the cam shaft direction of the engine is suppressed.

  A first aspect of the invention is a VTC actuator attached to an end of a camshaft and used for variable control of a cam phase, a spool valve that is held at the axis of the VTC actuator and switches a hydraulic circuit of the VTC actuator, A cam phase variable internal combustion engine that is attached to an engine body side member and includes a linear solenoid that drives the spool valve by a push rod that advances and retreats in the axial direction, and holds the push rod slidably in the axial direction The convex portion is formed on the axial center of the linear solenoid, and the concave portion in which the convex portion is loosely fitted is formed on the axial center of the VTC actuator.

  According to a second aspect of the present invention, in the cam phase variable internal combustion engine according to the first aspect of the invention, the convex portion has a convex tapered surface whose diameter decreases toward the VTC actuator, and the concave portion is the convex tapered surface. And a concave tapered surface facing each other with a predetermined gap.

  According to a third aspect of the present invention, in the cam phase variable internal combustion engine according to the second aspect of the invention, the convex taper surface and the concave taper surface each have a taper angle set in a range of 60 ° to 120 °. It is characterized by.

  According to a fourth aspect of the present invention, in the cam phase variable internal combustion engine according to the first to third aspects of the invention, the protrusion is set such that an amount of protrusion in the axial direction is equal to or less than a diameter of the push rod. And

  According to the present invention, it is possible to reduce the axial length of the linear solenoid while sufficiently securing the push rod holding length or the like by the convex portion, and the external dimension in the cam shaft direction of the engine is suppressed, so that the automobile The ease of installation in the engine room is improved. Moreover, when a convex part shall have a convex taper surface and a recessed part shall have a concave taper surface, the intensity | strength and rigidity of a convex part or a recessed part can be improved. Further, when the taper angle of the convex taper surface or the concave taper surface is set in the range of 60 ° to 120 °, it is difficult to form a sharp edge that reduces the strength and rigidity of the convex portion or the concave portion. In addition, in the case where the protruding amount in the axial direction of the convex portion is set to be equal to or less than the diameter of the push rod, the axial length of the concave portion can be shortened while ensuring a sufficient holding length (bearing length) of the push rod. The axial dimension of the VTC actuator can be shortened.

It is a principal part perspective view of the engine which concerns on embodiment. It is a disassembled perspective view of VTC which concerns on embodiment. It is a longitudinal cross-sectional view of VTC which concerns on embodiment. It is the IV section enlarged view in FIG. It is a graph which shows the relationship between a taper angle and rigidity ratio.

Hereinafter, an embodiment of a cam phase variable internal combustion engine according to the present invention will be described in detail with reference to the drawings. In the description of the embodiment, the left side in FIG. 1 is the front side, and the upper side is the upper side.
<< Configuration of Embodiment >>
<Overall configuration>
An engine (cam phase variable internal combustion engine) E shown in FIG. 1 is a DOHC 4-valve four-cycle in-line four-cylinder gasoline engine mounted on an automobile. An intake valve 2 for each cylinder is provided in the cylinder head 1. And an exhaust valve 3, an intake camshaft 4 and an exhaust camshaft 5 that drive the intake and exhaust valves 2 and 3. Both camshafts 4 and 5 are rotationally driven by the crankshaft 10 at a rotational speed of 1/2 through the crank sprocket 6, the cam chain 7, the intake cam sprocket 8, and the exhaust cam sprocket 9. The crankshaft 10 is connected to the piston 12 via a connecting rod 11 and drives an oil pump 14 installed obliquely downward via a chain 13.

  A VTC actuator 21 is fastened to the front end of the intake camshaft 4, and a linear solenoid 51 is attached to the cam cover 18 and the cam chain cover 19. The cylinder head 1 and the cylinder block 15 are formed with a hydraulic oil supply oil passage 16 for supplying hydraulic oil (engine oil) from the oil pump 14 to the VTC actuator 21. The cylinder head 1 is equipped with a normally open type electromagnetic shut valve (hydraulic shut-off means) 17, and the hydraulic oil supply oil passage 16 is communicated / blocked by the electromagnetic shut valve 17. The electromagnetic shut-off valve 17 is driven to be closed (cut off) by a drive current from an engine ECU (not shown).

<VTC actuator>
As shown in FIG. 2, the VTC actuator 21 includes a housing (first rotating member) 22 having an intake cam sprocket 8 formed on the outer periphery thereof, is rotatably held in the housing 22, and is then attached to the front end of the intake camshaft 4. A rotor (second rotating member) 23 to which the surface is fastened, a front plate 24 covering the front surface of the housing 22, a back plate 25 covering the rear surface of the housing 22, a reed valve 26 disposed on the inner peripheral side of the front plate 24, a lead A reed valve cover 27 for fixing the valve 26 to the rotor 23, a bias spring 28 for relatively rotating the housing 22 and the rotor 23 in the advance direction, a spool valve 29 installed at the shaft center, and a lock pin held by the rotor 23 33, lock pin spring for urging the lock pin 33 toward the back plate 25 Grayed 34, as a component bypass valve spring 37 or the like for urging the bypass valve 36 is held in the rotor 23, the bypass valve 36 in the back plate 25 side. The spool valve 29 includes a valve sleeve 38 held at the axis of the intake camshaft 4 and the rotor 23, a spool 39 slidably fitted in the valve sleeve 38, and the spool 39 attached to the linear solenoid 51 side. And a return spring 40 that is energized.

<Linear solenoid>
As shown in FIGS. 2 and 3, the linear solenoid 51 has a columnar solenoid body 52 connected to the engine ECU, and a push rod 53 held on the axis of the solenoid body 52. When the drive current from the engine ECU is supplied to the solenoid body 52, the push rod 53 moves back and forth (rightward in FIG. 3) and moves the spool valve 29 (spool 39) of the VTC actuator 21 to a predetermined position. Let

<Protrusions and recesses>
As shown in FIG. 4, the solenoid body 52 slidably holds the push rod 53 via a bearing 61 and has a convex portion 62 having a convex tapered surface 62 a at the center of the rear end thereof. The bearing 61 is press-fitted into the convex portion 62, and the rear end thereof is flush with the rear end of the convex portion 62. The solenoid body 52 is provided with a bearing (not shown) for holding the push rod 53 on the front end side in addition to the bearing 61 press-fitted into the convex portion 62. The protrusion amount L <b> 2 (see FIG. 3) of the convex portion 62 is set to be smaller than the diameter D of the push rod 53.

  On the other hand, the reed valve cover 27 engages the front end of the spool valve 29 and has a concave portion 65 having a concave tapered surface 65a at the center of the front end. The convex tapered surface 62a of the convex portion 62 and the concave tapered surface 65a of the concave portion 65 have the same taper angle θ (90 ° in the present embodiment) and a predetermined gap t (1 mm in the present embodiment). Confronted.

<< Operation of Embodiment >>
In the present embodiment, by adopting the above-described configuration, the substantial axial length L1 (see FIG. 3) of the solenoid main body 52 is made to protrude from the convex portion 62 while the push rod 53 is held with a sufficient holding length. The amount was reduced by L2. As a result, the outer dimension in the camshaft direction of the engine E is suppressed as compared with the conventional one, and the engine E can be mounted on an automobile having a relatively narrow engine room. Further, since the protrusion amount L2 of the convex portion 62 is set smaller than the diameter D of the push rod 53, the axial length of the concave portion 65 can be shortened. As a result, the reed valve cover 27 (ie, the VTC actuator 21) The axial dimension could be reduced.

  The inventors measured the change in rigidity of the convex portion 62 and the concave portion 65 while changing the taper angle θ of the convex tapered surface 62a and the concave tapered surface 65a in various ways. As a result, as can be seen from FIG. 5 that shows the rigidity ratio (stiffness ratio) when the taper angle θ is 90 °, the rigidity is 1.0, when the taper angle θ is 60 ° to 120 °, The rigidity of the convex part 62 and the concave part 65 is kept relatively high. However, when the taper angle θ is smaller than 60 °, the convex portion 62 side becomes an acute edge and the rigidity ratio becomes 0.7 or less, and when the taper angle θ is larger than 120 °, the concave portion 65 side becomes an acute angle edge and the rigidity ratio is reduced. Was found to be 0.7 or less.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, although the above embodiment is an application of the present invention to an in-line four-cylinder DOHC gasoline engine, it can naturally be applied to a diesel engine or the like. In the above embodiment, the intake camshaft is provided with the VTC actuator. However, the present invention may be applied to a cam phase variable internal combustion engine having the exhaust camshaft with the VTC actuator. In addition, the specific configuration of the engine and the variable valve operating apparatus can be changed as appropriate without departing from the gist of the present invention.

4 Intake camshaft 18 Cam cover (engine body side member)
19 Cam chain cover (engine body side member)
21 VTC actuator 27 Reed valve cover 29 Spool valve 39 Spool 51 Linear solenoid 52 Solenoid body 53 Push rod 61 Bearing 62 Convex part 62a Convex taper surface 65 Concave taper 65a Concave taper surface E Engine

Claims (4)

A VTC actuator attached to the end of the camshaft and used for variable control of the cam phase;
A spool valve that is held at the axis of the VTC actuator and switches a hydraulic circuit of the VTC actuator;
A cam phase variable internal combustion engine comprising a linear solenoid that is attached to an engine body side member and drives the spool valve by a push rod that advances and retreats in an axial direction,
A convex portion for holding the push rod slidably in the axial direction is formed on the axial center of the linear solenoid, and a concave portion in which the convex portion is loosely fitted is formed on the axial center of the VTC actuator. The cam phase variable internal combustion engine.   The convex portion has a convex taper surface with a diameter decreasing toward the VTC actuator, and the concave portion has a concave taper surface facing the convex taper surface with a predetermined gap. 1. The cam phase variable internal combustion engine described in 1.   The cam phase variable internal combustion engine according to claim 2, wherein the convex taper surface and the concave taper surface have respective taper angles set in a range of 60 ° to 120 °.   The cam phase variable internal combustion engine according to any one of claims 1 to 3, wherein the protrusion has an axial protrusion amount set to be equal to or less than a diameter of the push rod. .

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