US20080251042A1

US20080251042A1 - Device for Controlling Phase of Cam Shaft in Internal Combustion Engine and Phase Controlling device

Info

Publication number: US20080251042A1
Application number: US11/834,969
Authority: US
Inventors: Isao Hayase; Seiji Suga; Yoshinori Ichinosawa; Toshiyuki Kaneko
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2006-09-13
Filing date: 2007-08-07
Publication date: 2008-10-16
Also published as: JP2008069676A; KR20080024433A; DE102007037344A1; JP4238903B2

Abstract

A device for controlling a phase of a cam shaft in an internal combustion engine has a structure which can return a phase of a cam shaft to an intermediate position on the basis of its own power by utilizing a variable torque applied to a cam shaft at a time of starting an engine so as to lock, and has a high practicability and mass production performance. This device is provided with a first rotating body rotating together with a cam shaft, a second rotating body provided coaxially in the first rotating body so as to control a phase angle and rotating together with a sprocket, and a fixing mechanism fixing the phase angle, in which the fixing mechanism has a wedge member wherein a wedge-shaped portion is formed, the first rotating body and the second rotating body have contact surfaces brought into contact with the wedge member, and at least any one of the contact surfaces of the first rotating body and the second rotating body is formed such that a distance from a center of rotation to an application line of a load applied to the contact surface is smaller than a distance from the center of rotation to an application point of the load on the contact surface.

Description

FIELD OF THE INVENTION

The present invention relates to a device for controlling a phase angle between two rotating members, and more particularly to a variable valve timing mechanism (a valve timing controller, hereinafter refer to as VTC) for an internal combustion engine for controlling opening and closing timings of an intake valve and an exhaust valve driven via a cam shaft by a crank shaft.

DESCRIPTION OF RELATED ART

JP-A-11-343819 discloses a valve opening and closing timing control device (VTC) provided with a rotating shaft (a cam shaft) for opening and closing a valve, the rotating shaft being installed rotatably in a cylinder head of an internal combustion engine, a rotation transmitting member (a body) which is outside installed to the rotating shaft so as to be relatively rotatable in a predetermined range and to which a rotational power from the crank shaft is transmitted, a plurality of vanes provided in the rotating shaft so as to extend in a diametrical direction and arranged within a plurality of concave portions formed in the rotation transmitting member, a hydraulic pressure chamber formed between the rotating shaft and the rotation transmitting member and divided into a spark advance chamber (a spark advance hydraulic chamber) and a phase lag chamber (a phase lag hydraulic chamber) by the vane, a first fluid passage supplying and discharging a fluid to and from the spark advance chamber, a second fluid passage supplying and discharging the fluid to and from the phase lag chamber, and a phase holding mechanism (a lock mechanism or a fixing mechanism) holding a relative phase between the rotating shaft and the rotation transmitting member in the case that the relative phase between the rotating shaft and the rotation transmitting member is a predetermined phase.
JP-A-11-343819 discloses the phase holding mechanism structured such that a locking groove is formed in the rotation transmitting mechanism, the locking groove having a regulating portion extending to an outer side in a diametrical direction of the rotating shaft and a fan-shaped guide portion extending while being expanded in a diametrical direction from an outer end in the diametrical direction of the regulating portion, and the phase holding mechanism is provided with a locking member having a locking portion capable of holding the relative phase between the rotation transmitting member and the rotating shaft by being fitted to the regulating portion, and an energizing means energizing the locking member toward an inner side in the diametrical direction of the rotating shaft.
In the valve opening and closing timing control device, on the basis of the provision of the structure mentioned above, the locking portion of the locking member is fitted to the regulating portion of the locking groove at a time of an intermediate relative phase between a relative phase between the rotating shaft and the rotation transmitting member in a maximum spark advance state in which a volumetric capacity of the phase lag chamber is minimized by the vane and a relative phase between the rotating member and the rotation transmitting member in a maximum phase lag state in which a volumetric capacity of the spark advance chamber is minimized, the intermediate relative phase being the valve opening and closing timing at which the internal combustion engine can be started.

SUMMARY OF THE INVENTION

However, in the prior art including JP-A-11-343819, as a technical problem to be broken through for achieving the lock mechanism holding the relative phase between the maximum spark advance state and the maximum phase lag state by the hydraulic VTC, there can be listed up (1) a problem concerning a driving force up to a lock position, and (2) a problem concerning existence of a variable torque.
(1) Describing the driving force up to the lock position, it is necessary to be locked at the lock position at a time of starting the engine, and it is necessary that the phase is shifted to the lock position from the VTC phase at which the engine is stopped at the last time during a period under stopping and cranking from the last engine stop. Since an original driving force (a hydraulic pressure in a hydraulic drive or an electromagnetic force in an electromagnetic drive) of the VTC can not be obtained during the period mentioned above, it is necessary to secure a driving force heading for the lock position on the basis of its own power such as a spring force, a friction resistance or the like.
Further, in the case of locking the relative phase at the intermediate position, there may occur a case that a phase shifting direction at a time of returning to the lock position by its own power is the spark advance direction in addition to the phase lag direction in correspondence to the VTC phase at a time of the last engine stop. The variable torque is applied to the cam shaft on the basis of a reaction force from the valve spring, however, an average value always has a value in the phase lag direction on the basis of a friction resistance on a bearing or a cam surface. If the returning direction to the lock position is one direction to the phase lag direction, the friction resistance torque is expected, however, the friction resistance torque is not sufficient for the driving force in the case of the spark advance direction in addition to the phase lag direction. It is newly necessary to secure a driving force for shifting the phase in both directions.
(2) A description will be given of an existence of the variable torque. In order to lock the relative phase at the intermediate position, the driving force in the spark advance direction in addition to the phase lag direction is necessary for returning to the lock position by its own power. If it is simply necessary to generate self-driving forces in both directions, it is sufficient to combine two springs having different force directions. However, since the variable torque caused by the reaction force from the valve spring is applied to the cam shaft, the problem is complicated. Since the position to be returned by its own power is defined by a balance of a total moment including the variable torque applied to the cam shaft in addition to two spring forces (accurately the torques which the spring forces generated), the balancing position is necessarily fluctuated.
Further, in the torque fluctuation applied to the cam shaft, in the case of employing a system installing the lock pin as a means for locking the VTC phase, there is generated a problem that both the elements are hard to be fitted by making a fitting gap between the lock pin and the hole too small, and a slapping sound, a damage or the like tends to be generated by making the fitting gap between the lock pin and the hole too large.
If the lock pin and the fitting hole are formed in a tapered shape, it seems that the problem of being hard to be fitted as mentioned above can be solved. However, since a pin axis and a hole axis can not be completely brought into line with each other due to an error in a parts dimension and an assembly (particularly, a displacement in a diametrical direction can not be made zero), the problem of the slapping sound is left. Further, there is a risk of a new problems that a component force in a direction of canceling the lock pin is generated by forming in the tapered shape, and a reliability of a lock function is deteriorated.
In the valve opening and closing timing control device described in JP-A-11-343819, it is not said that the device sufficiently takes into consideration a structure for automatically returning to a lock position (hereinafter, refer to as an intermediate lock position) existing in an intermediate between the maximum spark advance state and the maximum phase lag state from both directions of the spark advance direction and the phase lag direction. In JP-A-11-343819, since the locking member energized in the radial direction has a great angle of inclination with respect to a moving direction of the locking member in the fan-shaped guide portion for guiding at a time of returning to the intermediate lock position, the locking member tends to be moved in a direction moving away from the intermediate lock position at a time when the torque fluctuation is applied. In order to prevent the locking member from being moved in the direction moving away from the intermediate lock position by the torque fluctuation, it is necessary to enlarge the energizing force of the energizing means for energizing the locking member toward an inner side in the diametrical direction of the rotating shaft. However, if the energizing force is enlarged, there is generated the other problem such as it is hard to smoothly move the locking member due to an enlargement of a friction force between the locking portion and the guide portion.
An object of the present invention is to provide a lock mechanism which can securely execute an automatic return to an intermediate lock position.
In order to achieve the object mentioned above, in accordance with the present invention, there is provided a device for controlling a phase of a cam shaft in an internal combustion engine comprising:
a first rotating body rotating together with a sprocket;
a second rotating body provided coaxially in the first rotating body so as to control a phase angle and rotating together with the cam shaft; and
a fixing mechanism fixing phase angles of the first rotating body and the second rotating body,
wherein the fixing mechanism has a wedge member in which a wedge-shaped portion is formed,
wherein the first rotating body and the second rotating body have contact surfaces brought into contact with the wedge member, and
wherein at least any one of the contact surfaces of the first rotating body and the second rotating body is inclined with respect to a direction of a rotating axis of the first rotating body and the second rotating body, and is formed such that a distance from a center of rotation to an application line of a load applied to the contact surface is smaller than a distance from the center of rotation to an application point of, the load on the contact surface.
At this time, it is preferable that the contact surface is provided so as to be inclined with respect to a radial direction from the center of rotation of the first rotating body and the second rotating body, whereby the distance from the center of rotation to the application line is smaller than the distance from the center of rotation to the application point.
Further, it is preferable that the first rotating body and the second rotating body have a second pair of contact surfaces which limit the phase angle in an inverse direction to a direction in which the phase angle is limited by a pair of contact surfaces provided in the first rotating body and the second rotating body and the wedge-shaped body, the second pair of contact surfaces limit the phase angle by being brought into contact via the intermediate member, and one of the second pair of contact surfaces is provided with a step portion enlarging a regulating range of the phase angle limited by the second pair of contact surfaces.
Further, it is preferable that the contact surfaces are formed with an angle equal to or less than 11 degree with respect to an inserting direction of the wedge member.
In order to achieve the object mentioned above, in accordance with the present invention, there is provided a device for controlling a phase of a cam shaft in an internal combustion engine comprising:
a first rotating body rotating together with a sprocket;
a second rotating body provided coaxially in the first rotating body so as to control a phase angle and rotating together with the cam shaft; and
a fixing mechanism fixing phase angles of the first rotating body and the second rotating body,
wherein the fixing mechanism has a wedge member in which a wedge-shaped portion is formed,
wherein the first rotating body and the second rotating body have receiving portions brought into contact with the wedge member,
wherein the receiving portions of the first rotating body and the second rotating body are respectively provided with contact surfaces which are narrowed with each other in an inserting direction of the wedge member, and
wherein at least any one contact surface of the contact surfaces is inclined with respect to a direction of a rotating axis of the first rotating body and the second rotating body, and is inclined with respect to a radial direction from a center of rotation of the first rotating body and the second rotating body.
At this time, it is preferable that the fixing mechanism has an elastic member energizing the wedge member in the inserting direction to the contact surfaces, and a hydraulic mechanism generating a hydraulic force in a direction of pulling out the wedge member from the contact surfaces.
Further, it is preferable that the first rotating body has an inner peripheral surface having a predetermined radius, the second rotating body has an outer peripheral surface having a predetermined radius, the first rotating body and the second rotating body are arranged such that the inner peripheral surface and the outer peripheral surface oppose to each other, the receiving portion of the first rotating body is provided in a side in which a diameter becomes larger than the inner peripheral surface, and the receiving portion of the second rotating body is provided in a side in which a diameter becomes smaller than the outer peripheral surface.
Further, in order to achieve the object mentioned above, in accordance with the present invention, there is provided a phase controlling device having a first rotating member and a second rotating member rotationally driven via the first rotating member, and controlling a phase angle corresponding to a relative rotational position between the first rotating member and the second rotating member,
wherein a drive member spark advance surface heading for a rotating direction of a whole of the device is formed in a drive side member in a power transmitting path from the first rotating member to the second rotating member,
wherein a driven member phase lag surface heading for an inverse direction to the rotating direction of the whole of the device is formed in a driven side member in the power transmitting path,
wherein one of the drive member spark advance surface and the driven member phase lag surface is inclined so as to head for an inner peripheral side within an axial vertical cross section with respect to a radial direction, and the other is inclined so as to head for an outer peripheral side within the axial vertical cross section,
wherein the device is provided with a wedge member sandwiched between the drive member spark advance surface and the driven member phase lag surface by the second rotating member changing the phase angle in the phase angle direction with respect to the first rotating member, an energizing means for energizing the wedge member to one of the directions of the rotating axes of the first rotating member and the second rotating member and a driving means for moving to the other of the directions of the rotating axes, and
wherein a distance between the drive member spark advance surface and the driven member phase lag surface in each of the axial vertical cross sections is made smaller to a cross section in an energizing direction by the energizing means.
At this time, it is preferable that the drive member spark advance surface is arranged in one of inner and outer sides of a cylinder surface having a predetermined radius, and the driven member phase lag surface is arranged in the other.
In accordance with the present invention, it is possible to provide a lock mechanism which can reduce a push-back force on the basis of a torque fluctuation applied to the wedge member from the inclined surface brought into contact with the wedge member, and can securely execute an automatic return to the intermediate lock position.
Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a side cross sectional view of a device for controlling a phase of a cam shaft in accordance with an embodiment 1 in a state in which an intermediate position lock is unlocked, provided as a cross sectional view taken along a line I-I in FIG. 2;

FIG. 2 is a horizontal cross sectional view of the device for controlling the phase of the cam shaft in accordance with the embodiment 1 in a state in which the intermediate position lock is unlocked, provided as a cross sectional view taken along a line II-II in FIG. 1;

FIG. 3 is a side cross sectional view of the device for controlling the phase of the cam shaft in accordance with the embodiment 1 in a state in which an intermediate phase is locked, provided as a cross sectional view taken along a line III-III in FIG. 4;

FIG. 4 is a horizontal cross sectional view of the device for controlling the phase of the cam shaft in accordance with the embodiment 1 in a state in which the intermediate phase is locked, provided as a cross sectional view taken along a line IV-IV in FIG. 3;

FIGS. 5A and 5B are explanatory views of an operation of the intermediate position lock in the embodiment 1, and provided as expansion plan views of a cross section of a circumference E in FIG. 2 or 4;

FIGS. 6A to 6D are explanatory views of the operation of the intermediate position lock in the embodiment 1, and provided as explanatory views of a returning process to an intermediate position from a phase lag side toward a spark advance direction;

FIGS. 7A to 7E are explanatory views of the operation of the intermediate position lock in the embodiment 1, and provided as explanatory views of a returning process to the intermediate position from the spark advance side toward the phase lag direction;

FIGS. 8A and 8B are views of a hydraulic path to a canceling hydraulic chamber of the intermediate position lock;

FIGS. 9A to 9C are explanatory views of a shape of a canceling piston in the embodiment 1;

FIGS. 10A to 10C are explanatory views of a shape of an adapter in the embodiment 1;

FIGS. 11A to 11F are explanatory views of a shape of a wedge member in the embodiment 1;

FIG. 12 is a side cross sectional view of a device for controlling a phase of a cam shaft in accordance with an embodiment 2 in a state in which an intermediate position is locked, and provided as a cross sectional view taken along a line XII-XII in FIG. 13;

FIG. 13 is a horizontal cross sectional view of the device for controlling the phase of the cam shaft in accordance with the embodiment 2 in a state in which the intermediate position is locked, and provided as a cross sectional view taken along a line XIII-XIII in FIG. 12;

FIGS. 14A to 14D are explanatory views of an operation of the intermediate position lock in the embodiment 2, and provided as explanatory views of a returning process to an intermediate position from a phase lag side toward a spark advance direction;

FIGS. 15A to 15D are explanatory views of the operation of the intermediate position lock in the embodiment 2, and provided as explanatory views of a returning process to the intermediate position from the spark advance side toward the phase lag direction;

FIGS. 16A to 16F are explanatory views of a shape of a wedge member in the embodiment 2; and

FIGS. 17A and 17B are explanatory views of a shape of a canceling piston in the embodiment 2.

DETAILED DESCRIPTION OF THE INVENTION

The following structures are provided in embodiments in accordance with the present invention.
A description will be given of an example in the case that the present invention is applied to a variable valve timing mechanism (VTC) for an internal combustion engine.
The VTC is provided with a first rotating member rotationally driven by a crank shaft of an internal combustion engine (hereinafter, refer simply to as an engine) in synchronous with the crank shaft, and a second rotating member rotationally driven via the first rotating member and integrally coupled to a cam shaft.
Accordingly, in the VTC, the first rotating member comes to a drive member, and the second rotating member comes to a driven member. Next, a drive member spark advance surface heading for a rotating direction of a whole of the device is fixed to the first rotating member, a driven member phase lag surface heading for an inverse direction to the rotating direction of the whole of the device is fixed to the second rotating member, the drive member spark advance surface is arranged in one of inner and outer sides of a cylinder surface having a predetermined radius, the driven member phase lag surface is arranged in the other, and the second rotating member changes a phase angle in a phase lag direction with respect to the first rotating member, thereby being provided with a wedge member sandwiched by the drive member spark advance surface and the driven member phase lag surface.
Further, a regulating portion limiting a phase change of the second rotating member in the spark advance direction with respect to the first rotating member is formed by fixing a drive member phase lag surface heading for the inverse direction to the rotating direction of the whole of the device to the first rotating member, fixing a driven member spark advance surface heading for the rotating direction of the whole of the device to the second rotating member, and bringing the drive member phase lag surface into contact with the driven member spark advance surface via an intermediate member.
Further, the VTC is provided with an energizing means for moving one of the wedge member and the intermediate member in one axial direction and utilizing a spring force or the like, and a driving means constituted by a hydraulic piston or the like moving in an inverse axial direction.
Further, the drive member spark advance surface and the driven member phase lag surface are formed such that a distance between them in a cross section vertical to the axis becomes smaller toward a cross section in an energizing direction by an energizing means, and a wedge member phase lag surface and a wedge member spark advance surface of the wedge member respectively brought into contact with these surfaces are formed such that a distance between them becomes smaller toward the cross section in the energizing direction by the energizing means. Further, a distance in the cross section vertical to the axis between the drive member phase lag surface and the driven member spark advance surface brought into contact via the intermediate member is formed such that a distance in a cross section in a driving direction by the driving means is larger than the distance in the cross section in the energizing direction by the energizing means.
In this case, in the VTC to which the present invention is applied, there is incorporated a phase shifting mechanism for changing a phase between the first rotating member and the second rotating member in a normal control state after starting the engine, in addition to the structure mentioned above.
As a result, during a cranking at an engine stop time or an engine restart time at which the phase shifting mechanism does not work and the wedge member and the intermediate member are going to move in one axial direction by the energizing means, it is possible to generate a driving force heading for a lock position existing at the intermediate position in a phase shifting range from whatever position on the basis of a principle described below, and it is possible to automatically return to a predetermined intermediate lock position so as to fix the phase.
In the state mentioned above which is not in the intermediate lock state yet, since there are not simultaneously achieved the state in which the wedge member is sandwiched between the drive member spark advance surface and the driven member phase lag surface and the phase shift in the phase lag direction is regulated, and the state in which the drive member phase lag surface and the driven member spark advance surface are brought into contact with each other view the intermediate member and the phase shift in the spark advance direction is regulated, the first rotating member (integrated with a sprocket) and the second rotating member (integrated with a cam shaft) can be relatively rotated so as to shift the phase.
At this time, since a positive torque (a torque in a phase lag direction for delaying the rotation of the cam shaft) is necessarily applied to the cam shaft in average due to a frictional resistance, the second rotating member necessarily applies the phase shift in the phase lag direction to the first rotating member. Accordingly, the wedge member is sandwiched between the drive member spark advance surface and the driven member phase lag surface so as to come to a state in which the phase shift in the phase lag direction is regulated. A variable torque changing over positive and negative ranges is applied to the cam shaft on the basis of a reaction force from a valve spring, and a peak value of a torque in the phase lag direction which is further larger than the average torque in the phase lag direction is applied to the wedge member mentioned above. However, even if the peak torque is applied, the wedge member is not pushed back in an inverse direction to the direction going to be moved by the energizing means because of the following reason.
The distance from a contact portion between the wedge member and the drive member spark advance surface to a contact portion between the wedge member and the driven member phase lag surface is structured such as to be reduced toward the energizing direction of the energizing means, however, since a rate is made sufficiently small, it is possible to make a component force in the opposite energizing direction (a force intending to push back the wedge member) sufficiently small in comparison with a contact force applied to the wedge member on the basis of the torque in the phase lag direction. On the other hand, since a frictional resistance (a force preventing the wedge member from being pushed back) applied to the wedge member can become large approximately in proportion to the contact force mentioned above, the component force in the opposite energizing direction is canceled by the frictional resistance.
Since the variable torque changing over the positive and negative ranges is applied from the cam shaft, the second rotating member is going to shift the phase in the spark advance direction by the negative torque with respect to the first rotating member in another moment. Since the phase shift to the spark advance direction can be executed yet in this stage which is not in the intermediate lock state as mentioned above, the wedge member is released from the sandwiched state, and the contact force between the drive member spark advance surface and the driven member phase lag surface disappears. As a result, the wedge member is moved in one axial direction by the energizing means utilizing the spring force or the like without being obstructed by the friction resistance. The movement of the wedge member in the axial direction means an expansion of the distance between the drive member spark advance surface and the driven member phase lag surface, and the fixed second rotating member of the driven member phase lag surface is automatically shifted phase in the spark advance direction with respect to the fixed first rotating member of the drive member spark advance surface.
Since the regulating portion of the phase shift in the spark advance direction via the intermediate member is formed between the first rotating member and the second rotating member, the automatic phase shift to the spark advance direction mentioned above carries over to this regulating position so as to be finished. At this time point, there are simultaneously achieved the state in which the wedge member is sandwiched between the drive member spark advance surface and the driven member phase lag surface and the phase shift in the phase lag direction is regulate, and the state in which the drive member phase lag surface and the driven member spark advance surface are brought into contact with each other via the intermediate member and the phase shift in the spark advance direction is regulated, and there is achieved the lock state in which the first rotating member and the second rotating member can not be relatively rotated in either direction.
If a first explosion is executed after the lock state so as to start the engine, and a sufficient hydraulic pressure is supplied from a fuel supply pump, the driving means using the hydraulic piston or the like is actuated so as to drive the wedge member and the intermediate member in the inverse axial direction. If the wedge member is moved in the axial direction, a gap is generated with respect to at least one of the drive member spark advance member and the driven member phase lag surface, and the second rotating member can be shifted phase in the phase lag direction with respect to the first rotating member. Further, even if the intermediate member is moved in the axial direction, a gap is generated with respect to at least one of the drive member phase lag surface and the driven member spark advance surface, and the second rotating member can be shifted phase in the spark advance direction with respect to the first rotating member. In other words, it is known that the lock position mentioned above is an intermediate position in the phase shift region in the variable valve timing mechanism VTC. If the lock state is canceled as mentioned above, it is possible to execute a phase shift control in a normal state using the conventional phase shifting mechanism which is independently incorporated from the portions of the present invention.
In the description mentioned above, structurally, the drive member spark advance surface and the driven member phase lag surface essentially correspond to the surfaces respectively directed to the spark advance direction and the phase lag direction, and the drive member phase lag surface and the driven member spark advance surface essentially correspond to the surfaces respectively directed to the phase lag direction side and the spark advance direction side. On the other hand, the drive member spark advance surface and the driven member phase lag surface correspond to the surfaces regulating the phase shift in the phase lag direction of the second rotating member with respect to the first rotating member, and the drive member phase lag surface and the driven member spark advance surface respectively correspond to the surfaces regulating the phase shift in the spark advance direction of the second rotating member with respect to the first rotating member. Accordingly, in light of function, the drive member spark advance surface and the driven member phase lag surface respectively correspond to a phase lag direction phase shift regulating surface formed in the first rotating member (the drive member) and a phase lag direction phase shift regulating surface formed in the second rotating member (the driven member). Further, the drive member phase lag surface and the driven member spark advance surface respectively correspond to a spark advance direction phase shift regulating surface formed in the first rotating member (the drive member) and a spark advance direction phase shift regulating surface formed in the second rotating member (the driven member).
In this case, in embodiments described below, the wedge member and the intermediate member are structured by one member.

EMBODIMENT 1

A description will be given below of a device for controlling a phase of a cam shaft in an internal combustion engine having an intermediate position lock function in accordance with an embodiment 1 of the present invention with reference to FIGS. 1 to 8B. FIG. 1 is a side cross sectional view in a state in which an intermediate position lock is unlocked in accordance with the present embodiment, and shows a cross section taken along a line I-I in FIG. 2. FIG. 2 is a horizontal cross sectional view taken along a line II-II in FIG. 1. FIG. 3 is a side cross sectional view in a state in which the intermediate position is locked in accordance with the present embodiment, and shows a cross section taken along a line III-III in FIG. 4. FIG. 4 is a horizontal cross sectional view taken along a line IV-IV in FIG. 3. FIGS. 5A and 5B are explanatory views of an operation of the intermediate position lock in which a cross section of a circumference C and the like in FIG. 2 or 4 are expanded. FIGS. 6A to 6D are explanatory views of the operation of the intermediate position lock in the embodiment 1, and explanatory views of a returning process to an intermediate position from a phase lag side toward a spark advance direction. FIGS. 7A to 7E are explanatory views of the operation of the intermediate position lock in the embodiment 1, and explanatory views of a returning process to the intermediate position from the spark advance side toward the phase lag direction. FIGS. 8A and 8B are views of a hydraulic path to a canceling hydraulic chamber of the intermediate position lock. FIGS. 9A to 9C, 10A to 10C and 11A to 11F are respectively explanatory views of shapes of a canceling piston, an adapter and a wedge member in the present embodiment.
In FIGS. 1 to 7E, a sprocket 1 constituting the first rotating member is decelerated one half via a toothed belt (not shown) engaging with a tooth portion 1 a in an outer periphery so as to be rotationally driven by a crank shaft of the engine. A body 2 and a front plate 3 are fixed to the sprocket 1 by an assembling bolt 4 so as to be integrated. Accordingly, in the present embodiment, the first rotating member is structured so as to include the sprocket 1, the body 2 and the front plate 3. A vane 6 corresponding to the second rotating member is fixed to the cam shaft 5 by a center bolt 7. As shown in FIGS. 2 and 4, three pairs of phase lag hydraulic chambers 8 and spark advance hydraulic chambers 9 are formed between the body 2 and the vane 6, both end opening portions in an axial direction are closed by the sprocket 1 and the front plate 3 and a gap in a radial direction is sealed by an apex seal 10, whereby a sealed space is formed.
In an intermediate position lock unlocked state shown in FIGS. 1 and 2, a hydraulic pressure is introduced to a canceling hydraulic chamber 12 surrounded by the sprocket 1, the body 2, the canceling piston 11 and the like from a fuel supply pump (not shown) driven by the engine via a hydraulic path shown in FIGS. 8A and 8B, and the canceling piston 11 is in a state in which the canceling piston 11 is pushed out to the maximum to a front side (a left direction in FIG. 1) against a force of a lock spring 13. The canceling piston 11 is brought into contact with the front plate 3, whereby a maximum displacement to the front side is regulated. Further, a pin 14 fixed to the body 2 is inserted to a groove portion 11 a, and prevents the canceling piston 11 from rotating freely rotating around the axis in an inner portion of the body 2. An adapter 15 is fixed to the canceling piston 11, a part thereof is fitted to a groove portion 16 a of a wedge member 16 and the wedge member 16 is pushed out to a front side. The adapter 15 is fixed to the canceling piston 11 by an injection pin 17.
A description will be given of the hydraulic path reaching the canceling hydraulic chamber 12 with reference to FIGS. 8A and 8B. The hydraulic pressure is first supplied to a canceling hydraulic groove 5 a corresponding to one of hydraulic grooves formed on an outer periphery of the cam shaft 5 from a hydraulic pressure supply hole of a cam shaft bearing shown by a single-dot chain line around the cam shaft 5. The other two hydraulic grooves correspond to grooves for supplying the hydraulic pressure to the phase lag hydraulic chamber 8 a and the spark advance hydraulic chamber 9, however, the thereafter path thereof is the same as the prior art, and a description thereof will be omitted. The hydraulic pressure supplied to the canceling hydraulic groove 5 a reaches an outer peripheral cylinder surface of the cam shaft 5 supporting a rotation of the sprocket 1 via a first fuel supply hole 5 b, a second fuel supply hole 5 c and a third fuel supply hole 5 d. A groove portion 1 c formed in a crescent shape by a cutter is formed on an inner peripheral cylinder surface of the sprocket 1 corresponding to an opening portion of the third fuel supply hole 5 d. The groove portion 1 c has a sufficient length in a circumferential direction, and a communication with the third fuel supply hole 5 d is always kept even if the sprocket 1 and the cam shaft 5 are relatively rotated in a control range of a phase angle. A hydraulic pressure is supplied to the canceling hydraulic chamber 12 from the groove portion 1 c via the fourth fuel supply hole 1 d and the fifth fuel supply hole 1 e. In this case, an opening to an outer peripheral portion of the fourth fuel supply hole 1 d is closed by a plug 18.
A drive member spark advance surface 2 a and a drive member phase lag surface 2 b are formed on one of cylindrical inner peripheral surface portions formed at three positions in the body 2, and a driven member phase lag surface 6 a and a driven member spark advance surface 6 b are formed in a cylindrical outer peripheral surface portion in a center portion of the vane 6 opposing to an inner side thereof. The drive member spark advance surface 2 a and the drive member phase lag surface 2 b are inclined to an inner peripheral side with respect to a radial direction as shown in FIG. 4, and are formed in such a inclined shape that a mutual interval is reduced toward an axial direction in an engine side as shown in FIGS. 5A to 7E. In other words, the drive member spark advance surface 2 a is inclined in a spark advance direction toward the axial direction mentioned above, and the drive member phase lag surface 2 b is inclined in a phase lag direction toward the axial direction mentioned above. Particularly, the drive member phase lag surface 2 b is formed only a part in the engine side in the axial direction of the body 2, however, the drive member spark advance surface 2 a is formed longer in the front side in the axial direction. The other phase lag flank 2 d coming next to a step portion 2 c is formed in the front side of the drive member phase lag surface 2 b, whereby a distance in a circumferential direction between the phase lag flank 2 d and the drive member spark advance surface 2 a becomes larger step by step than a distance in a circumferential direction between the drive member phase lag surface 2 b and the drive member spark advance surface 2 a. On the other hand, the driven member phase lag surface 6 a and the driven member spark advance surface 6 b are inclined so as to head for an outer peripheral side with respect to a radial direction within a cross section, however, are straight shapes having no change in an axial direction, as is understood by comparing the shapes respectively shown in FIGS. 2 and 4.
The wedge member 16 in the embodiment 1 is a member doubling as both functions of a wedge member regulating a phase lag direction phase change of the body 2 corresponding to the first rotating member and the vane 6 corresponding to the second rotating member, and an intermediate member regulating a spark advance direction phase change. Accordingly, the wedge member 16 may be called as the regulating member 16. In the wedge member 16, there are formed an inner peripheral side spark advance surface 16 c corresponding to a wedge member spark advance surface, an outer peripheral side phase lag surface 16 d corresponding to a wedge member phase lag surface, an outer peripheral side spark advance surface 16 e corresponding to an intermediate member spark advance surface and an inner peripheral side phase lag surface 16 b corresponding to an intermediate member phase lag surface. In this case, the spark advance surface and the phase lag surface essentially express surfaces directed to the spark advance direction side and the phase lag direction side, respectively. The outer peripheral side phase lag surface 16 d and the inner peripheral side spark advance surface 16 c are respectively brought into contact with the drive member spark advance surface 2 a and the driven member phase lag surface 6 a in function so as to structure a phase lag direction phase shift regulating surface regulating a phase shift in the phase lag direction. The inner peripheral side phase lag surface 16 b and the outer peripheral side spark advance surface 16 e are respectively brought into contact with the driven member spark advance surface 6 b and the drive member phase lag surface 2 b in function so as to structure a spark advance direction phase shift regulating surface regulating the phase shift in the spark advance direction.
The inner peripheral side phase lag surface 16 b corresponding to the intermediate member phase lag surface and the inner peripheral side spark advance surface 16 c corresponding to the wedge portion spark advance surface are always constrained to the driven member phase lag surface 6 a and the driven member spark advance surface 6 b, respectively, and the wedge member 16 is always moved in a circumferential direction together with the vane 6. The outer peripheral side phase lag surface 16 d corresponding to the wedge member phase lag surface and the outer peripheral side spark advance surface 16 e corresponding to the intermediate member spark advance surface become respectively opposed to the drive member spark advance surface 2 a and the phase lag flank 2 d by the wedge member 16 being pushed out to the front side in the intermediate position lock unlocked state shown in FIGS. 5A and 5B, and have a gap in a circumferential direction with respect to at least one opposing surface. Accordingly, the body 2 and the vane 6 can be shifted phase at only a phase angle corresponding to a magnitude of the gap. FIG. 5A shows a state in which the lock is unlocked while keeping the phase of the body 2 and the vane 6 in the intermediate lock phase. A gap L1 in the phase lag direction of the wedge member 16 is obtained by a product between a distance L at which the wedge member 16 in the intermediate position lock state in FIG. 5B is moved to the position of the wedge member 16 in FIG. 5A in the axial direction, and a tangent of an angle of inclination θ1 in FIGS. 5A and 5B of the drive member spark advance surface 2 a. In the case that the angles of inclination in FIGS. 5A and 5B of the drive member phase lag surface 2 b and the phase lag flank 2 d are both θ2 and equal to each other, a gap L2 in the spark advance direction of the wedge member 16 is obtained by a sum of the product mentioned above between the moving distance L of the wedge member 16 above and the tangent of the angle of inclination θ2 and a length in the circumferential direction of the step portion 2 c. In other words, a phase control range in the spark advance side is set larger in comparison with a phase control range in the phase lag side from the intermediate position lock position in the VTC in accordance with the embodiment 1.
The body 2 and the vane 6 can be shifted phase to the phase lag direction (a direction in which a rotational phase of the cam shaft is delayed) by introducing a boosted oil to the phase lag hydraulic chamber 8 so as to increase a volumetric capacity thereof and discharging the oil in the spark advance hydraulic chamber 9 so as to reduce a volumetric capacity thereof, and can be inversely shifted phase to the spark advance direction (a direction in which the rotational phase of the cam shaft is advanced) by increasing the volumetric capacity of the spark advance hydraulic chamber 9 and reducing the volumetric capacity of the phase lag hydraulic chamber 8. A vane type phase shifting mechanism using the conventional hydraulic system is formed thereby. If the canceling piston 11 is kept at the intermediate position lock unlocked position as shown in FIG. 1 or 5A, it is possible to execute the phase control of the VTC by the phase shifting mechanism.
In the intermediate position lock state shown in FIGS. 3 and 4, the hydraulic pressure in the canceling hydraulic chamber 12 is not introduced, and the canceling piston 11 is kept in a state of being pushed into the engine side (a right direction in FIG. 1) to the maximum by a force of the lock spring 13. In this embodiment 1, the canceling piston 11 is regulated a maximum displacement to the engine side by the wedge member 16 moving together in the axial direction being wedge engaged with the body 2 and the vane 6. At this time, the wedge member 16 is closely attached to all of the drive member spark advance surface 2 a, the drive member phase lag surface 2 b, the driven member phase lag surface 6 a and the driven member spark advance surface 6 b around the wedge member 16, and the body 2 and the vane 6 are regulated the phase shift to the phase lag direction by the wedge member 16 being sandwiched by the drive member spark advance surface 2 a and the driven member phase lag surface 6 a, and are regulated the phase shift to the spark advance direction by the wedge member 16 doubling with the function of the intermediate member being sandwiched by the drive member phase lag surface 2 b and the driven member spark advance surface 6 b. In other words, the body 2 corresponding to the first rotating member and the vane 6 corresponding to the second rotating member come to the locked state. In this case, in the embodiment 1, a run-off portion 1 b is formed in a portion to which a leading end of the wedge member 16 comes close in the sprocket 1, and the wedge member 16 is closely attached to the periphery securely at a time when the canceling piston 11 displaces to the engine side to the maximum, whereby there is achieved a structure in which a rattling with respect to the variable torque is hard to be generated.
Each of FIGS. 6A to 6D shows an example of a process of being shifted phase to a predetermined intermediate lock position by its own power during a cranking such as an engine stop time and a next engine start time so as to come to the lock state, at a time when the engine is stopped in a state in which the VTC is operated in a side closer to the phase lag than the intermediate lock position. FIG. 6A shows a state in which the wedge member 16 is exposed to the hydraulic force from the canceling piston 11 in the groove portion 16 a so as to be moved in a downward direction in the drawing during the operation of the engine, whereby the intermediate lock mechanism is unlocked, and is controlled the phase as the VTC to a side closer to the phase lag than the intermediate lock position. If the hydraulic pressure supplied to the canceling piston 11 runs short in accordance with the engine stop, the wedge member 16 is exposed to the force of the lock spring 13 as shown in FIG. 6B so as to be moved to an upper side (an engine side) in the drawing even if the phase is unchanged. On the basis of the movement in the axial direction, the wedge member 16 comes to a state of being sandwiched between the drive member spark advance surface 2 a and the driven member phase lag surface 6 a as shown in FIG. 6B. In this case, a hatched portion in the drawing shows a portion in which surfaces come in contact with each other. As a result, a rotating force is transmitted to the vane 6 from the body 2 via the wedge member 16, the cam shaft 5 starts rotating, and a variable torque on the basis of a reaction force from a valve spring (not shown) is applied to the power transmitting portion mentioned above. The variable torque is a torque which is changed over positive and negative regions. The positive torque for shifting the phase of the vane 6 therein in the phase lag direction is applied, and the reaction force from the drive member spark advance surface 2 a intends to push back the wedge member 16, however, since an angle of inclination in the axial direction of the drive member spark advance surface 2 a is small, a component force in the axial direction is small and is obstructed by a frictional resistance, so that the wedge member 16 is not pushed back to the lower side in the drawing. A description will be given further in detail of a reason why the component force in the axial direction mentioned above becomes small. A magnitude of a friction force resisting against the wedge member 16 being pushed back is in proportion to the reaction force (the contact force) from the drive member spark advance surface 2 a. Since the reaction force from the drive member spark advance surface 2 a is applied to the drive member spark advance surface 2 a approximately vertically, and the drive member spark advance surface 2 a is inclined with respect to the radial direction as shown in FIG. 4, the reaction force is divided into a component in a radial direction and a component in a direction vertical thereto. Only the latter is shown as an in-plane force on FIG. 6. The direction thereof is a direction vertical to a line of inclination of the drive member spark advance surface 2 a on FIG. 6. A force in an axial direction intending to push back the wedge member 16 in the axial direction is applied as the component force in the axial direction of the in-plane force. In other words, an inclination to an inner peripheral side of the drive member spark advance surface 2 a with respect to the radial direction as shown in FIG. 4 first makes a rate of the in-plane force with respect to the reaction force from the drive member spark advance surface 2 a small, and a small angle of inclination with respect to the axial direction of the drive member spark advance surface 2 a on FIG. 6 makes the rate of the component force in the axial direction with respect to the in-plane force mentioned above small. In other words, even if the angle of inclination in FIG. 6 is not extremely small, it is possible to make the force in the axial direction pushing back the wedge member 16 smaller in comparison with the frictional resistance by applying an inclination with respect to the radial direction in FIG. 4, and it is possible to inhibit the wedge member 16 from being pushed back to the lower side in the drawing by the variable torque. The fact that the angle of inclination in FIG. 6 may not be extremely small means the fact that it is possible to secure the gap L1 in the phase lag direction in FIG. 5A larger than the limited moving distance L in the axial direction of the wedge member 16, thereby serving for securing the control region from the intermediate lock position to the phase lag side wide.
On the other hand, if the negative torque for shifting the phase of the vane 6 to the spark angle direction is applied, the force sandwiching the wedge member 16 disappears and the frictional resistance runs short, so that the wedge member 16 is moved to an upper side in the drawing as shown in FIG. 6C on the basis of the force of the lock spring 13. At this time, the wedge member 16 and the vane 6 are shifted the phase to the spark advance direction. If the phase shift to the spark advance direction makes progress, the wedge member 16 finally comes to the lock state sandwiched by the drive member phase lag surface 2 b and the driven member spark advance surface 6 b as the intermediate member as sown in FIG. 6D. In other words, it is possible to automatically return in the spark advance direction toward the intermediate lock position by utilizing the variable torque applied to the cam shaft 5, thereby forming the lock state.
Each of FIGS. 7A to 7D shows an example of a process of being shifted phase to a predetermined intermediate lock position by its own power during a cranking such as an engine stop time and a next engine start time so as to come to the lock state, at a time when the engine is stopped in a state in which the VTC is operated in a side closer to the spark advance than the intermediate lock position. FIG. 7A shows a state in which the wedge member 16 is exposed to the hydraulic force from the canceling piston 11 in the groove portion 16 a so as to be moved in a downward direction in the drawing during the operation of the engine, whereby the intermediate lock mechanism is unlocked, and is controlled the phase as the VTC to a side closer to the spark advance than the intermediate lock position. If the hydraulic pressure supplied to the canceling piston 11 runs short in accordance with the engine stop, the wedge member 16 is exposed to the force of the lock spring 13 as shown in FIG. 7B so as to be moved to an upper side (an engine side) in the drawing even if the phase is unchanged. On the basis of the movement in the axial direction, the leading end portion of the wedge member 16 is brought into contact with the step portion 2 c of the body 2 as shown in FIG. 7B so as to stop. If the cranking at a time of starting the engine is started, the sprocket 1 and the body 2 starts rotating by being driven by the crank shaft, however, the driving force is not transmitted from the vane 6 until the wedge member 16 comes to the state of being sandwiched between the drive member spark advance surface 2 a and the driven member phase lag surface 6 a, and the wedge member 16 stands still. In other words, the wedge member 16 necessarily executes the phase shift in the phase lag direction with respect to the body 2 until the wedge member 16 comes into contact with the drive member spark advance surface 2 a. In this process of the phase shift in the phase lag direction, the wedge member 16 is not moved in the axial direction first as shown in FIG. 7C, and executes the phase shift to the phase lag direction (the direction of the intermediate lock position) in a state in which the leading end portion is along the step portion 2 c of the body 2. Next, if the phase shift in the phase lag direction makes progress and the leading end portion of the wedge member 16 passes through the range of the step portion 2 c, the wedge member 16 executes the movement in the axial direction on the basis of the force of the lock spring 13, and comes to the state in which the wedge member 16 and the drive member phase lag surface 2 b comes into contact with each other as shown in FIG. 7D. In FIG. 7D, since the wedge member 16 is going to shift the phase in the phase lag direction as before, the contact force mentioned above can not generate such a frictional resistance as to inhibit the wedge member 16 from being pushed in by the lock spring 13, and the phase shift in the phase lag direction further makes progress. Finally, the lock state in FIG. 7E is achieved, and it is possible to automatically return in the phase lag direction toward the intermediate lock position.
As mentioned above, in the embodiment 1, it is possible to automatically return toward the intermediate lock position both from the phase lag side and from the spark advance side. Further, it is possible to exclude the play on the contact surface around the wedge member 16 at a time of locking, and it is possible to enlarge the control range of the phase shift in the intermediate position lock unlocked state by the step portion 2 c being formed in the body 2.

EMBODIMENT 2

Next, a description will be given of a device for controlling a phase of a cam shaft in an internal combustion engine having an intermediate position lock function in accordance with an embodiment 2 of the present invention with reference to FIGS. 12 to 17B. FIG. 12 is a side cross sectional view in a state in which an intermediate position is locked in accordance with the present embodiment, and shows a cross section taken along a line XII-XII in FIG. 13. FIG. 13 is a horizontal cross sectional view taken along a line XIII-XIII in FIG. 12. FIGS. 14A to 14D and 15A to 15D are explanatory views of an operation of the intermediate position lock in the present embodiment, explanatory views of a returning process to an intermediate position from a phase lag side toward a spark advance direction and explanatory views of a returning process to the intermediate position from the spark advance side toward the phase lag direction. FIGS. 16A to 16F and 17A to 17B are respectively explanatory views of shapes of a wedge member and a canceling piston corresponding to constituting part of the present embodiment.
In the embodiment 2, shapes of a sprocket 19, a body 20, a front plate 21, a vane 22, a canceling piston 23, a canceling hydraulic chamber 24 and a wedge member 25 are changed from those of the embodiment 1, and a spacer 26 is newly added.
A drive member spark advance surface 20 a and a drive member phase lag surface 20 b formed in the body 20 in the embodiment 2 are both formed as a straight surface having no inclination in an axial direction. An outer peripheral side phase lag surface 25 a and an outer peripheral side spark advance surface 25 b of the wedge member 25 are straight in the axial direction, and are respectively constrained to the drive member spark advance surface 20 a and the drive member phase lag surface 20 b of the body 20. In other words, in the embodiment 2, the wedge member 25 rotates together with the body 20 and does not rotate relatively. In the embodiment 1, the displacement in the circumferential direction between the canceling piston 11 incorporated in the body 2 and the wedge member 16 can be achieved via the adapter 15, however, this structure is not necessary in the embodiment 2, and the embodiment 2 is structured such that the canceling piston 23 and the wedge member 25 are directly coupled by a pin 27 so as to be integrally moved in the axial direction. Further, in accordance with this structure, since it is possible to inhibit the canceling piston 23 from rotating in an inner portion of the body 20, the groove portion 11 a of the canceling piston and the pin 14 in the embodiment 1 are not necessary. As a result, as is known from a comparison between FIGS. 9A to 9C and FIG. 17, the canceling piston 23 in the embodiment 2 is formed as a simpler form having a reduced protruding portion.
On the other hand, in the embodiment 2, an inclination in the axial direction is formed in a driven member phase lag surface 22 a formed in the vane 22 as shown in FIGS. 14A to 14D and FIGS. 15A to 15D. However, a driven member spark advance surface 22 b and a spark advance flank 22 d are formed in a straight shape in the axial direction. In other words, in the embodiment 2, the surface having the inclination in the axial direction is formed in the vane 22 as is different from the embodiment 1, however, the inclined surface is provided only at one position, and the number of the inclined surface is minimized.
The inclination in the axial direction is formed in an inner peripheral side spark advance surface 25 c of the wedge member 25 brought into contact with each of the wall surfaces of the vane 22 mentioned above in correspondence to the driven member phase lag surface 22 a, however, an inner peripheral side phase lag surface 25 d is formed as a straight surface in the axial direction. As a result, even in the wedge member 25, the surface inclined in the axial direction is provided only at one position constituted by the inner peripheral side spark advance surface 25 c.
The “spark advance surface” and the “phase lag surface” are structurally defined in the same way as that of the embodiment 1, and these surfaces can be defined as the functional “regulating surface” in the same manner as the embodiment 1. If the wedge member 25 is divided into the wedge member and the intermediate member in the same manner as the embodiment 1, the outer peripheral phase lag surface 25 a and the inner peripheral side spark advance surface 25 c respectively correspond to the wedge member phase lag surface and the wedge member spark advance surface, and the outer peripheral side spark advance surface 25 b and the inner peripheral side phase lag surface 25 d respectively correspond to the intermediate member spark advance surface and the intermediate member phase lag surface.
In this case, in the description mentioned above and the following description, the surface expressed as the “surface inclined in the axial direction” is a convenient expression on the assumption of a shape after expanding a cylindrical surface on a plane, and it goes without saying that the surface is actually constituted by a spiral curved surface. Further, each of the wall surfaces is inclined in an inner peripheral direction or an outer peripheral direction with respect to the radial direction within a cross section perpendicular to the axis, however, this serves for securing the control region from the intermediate lock position to the phase lag side wide while inhibiting the wedge member 25 from being pushed back to the lower side in the drawing on the basis of the variable torque, that is, while securing its own returning performance in the spark advance direction, in the same manner as the embodiment 1.
In the embodiment 2, a step portion 20 c is formed in an end portion in the sprocket 19 side of a bore portion of the body 20 accommodating the canceling piston 23, and a spacer 26 is incorporated in the step portion 20 c. In the intermediate position lock state in FIG. 12. The canceling piston 23 is energized by the lock spring 13 so as to be brought into contact with the end surface of the sprocket 19 via the spacer 26 and stop. At this time, since the wedge member 25 stops working with the canceling piston 23, the leading end portion thereof is not engaged by wedge so as to stop. In the intermediate position lock state, a gap theoretically exists between the wedge member 25 and the peripheral wall surface, however, it is possible to select a thickness of the spacer 26 so as to regulate a stop position in the axial direction of the canceling piston 23 and the wedge member 25, thereby regulating the gap between the wedge member 25 and the peripheral wall surface to a small value that the rattling is out of the question. On the other hand, since the wedge member 25 is not closely attached to the peripheral wall surface simultaneously, and there is no risk that a biting phenomenon of the wedge is generated, it is possible to securely drive the wedge member 25 in an opposite direction to the energizing force at a time of intending to cancel the intermediate position lock state.
Each of FIGS. 14A to 14D shows an example of a process of being shifted phase to a predetermined intermediate lock position by its own power during a cranking such as an engine stop time and a next engine start time so as to come to the lock state, at a time when the engine is stopped in a state in which the VTC in accordance with the embodiment 2 is operated in a side closer to the phase lag than the intermediate lock position. FIG. 14A shows a state in which the wedge member 25 is exposed to the hydraulic force from the canceling piston 23 via the pin 27 so as to be moved in a downward direction in the drawing during the operation of the engine, whereby the intermediate lock mechanism is unlocked, and is controlled the phase as the VTC to a side closer to the phase lag than the intermediate lock position. If the hydraulic pressure supplied to the canceling piston 23 runs short in accordance with the engine stop, the wedge member 25 is exposed to the force of the lock spring 13 as shown in FIG. 14B so as to be moved to an upper side (an engine side) in the drawing even if the phase is unchanged. On the basis of the movement in the axial direction, the wedge member 25 comes to a state of being sandwiched between the drive member spark advance surface 20 a and the driven member phase lag surface 22 a as shown in FIG. 14B. In this case, a hatched portion in the drawing shows a portion in which surfaces come in contact with each other. As a result, a rotating force is transmitted to the vane 22 from the body 20 via the wedge member 25, the cam shaft 5 starts rotating, and a variable torque on the basis of a reaction force from a valve spring (not shown) is applied to the power transmitting portion mentioned above. Even if the positive torque in the variable torque is applied, the wedge member 25 is not pushed back to the lower side in the drawing for the same reason as the embodiment 1, because the small inclination in the axial direction is formed in the inner peripheral side spark advance surface 25 c of the wedge member 25 and the driven member phase lag surface 22 a. If the negative torque for shifting the phase of the vane 22 in the spark advance direction is applied, the frictional resistance runs short, so that the wedge member 25 is moved further to the upper side in the drawing while executing the phase shift in the spark advance direction as shown in FIG. 14C on the basis of the force of the lock spring 13. Finally, the wedge member 25 comes to the lock state sandwiched by the drive member phase lag surface 20 b and the driven member spark advance surface 22 b, serving as the intermediate member as shown in FIG. 14B. In this case, in the embodiment 2, since the canceling piston 23 is brought into contact with the sprocket 19 via the spacer 26 so as to stop, the wedge member 25 is not closely attached to the peripheral wall surface simultaneously so as to be engaged by wedge in narrow sense in FIG. 14D, but is constrained with a small gap. A hatched portion in the drawing shows by interpreting that the constrained surface is a substantial contact portion in this case. In the embodiment 2, it is possible to automatically return in the spark advance direction toward the intermediate lock position by utilizing the variable torque applied to the cam shaft 5 so as to achieve the lock state.
Each of FIGS. 15A to 15D shows an example of a process of being shifted phase to a predetermined intermediate lock position by its own power during a cranking such as an engine stop time and a next engine start time so as to come to the lock state, at a time when the engine is stopped in a state in which the VTC in accordance with the embodiment 2 is operated in a side closer to the spark advance than the intermediate lock position. FIG. 15A shows a state in which the wedge member 25 is moved in a downward direction in the drawing on the basis of the hydraulic pressure during the operation of the engine, whereby the intermediate lock mechanism is unlocked, and is controlled the phase as the VTC to a side closer to the spark advance than the intermediate lock position. If the hydraulic pressure mentioned above runs short in accordance with the engine stop, the wedge member 25 is exposed to the force of the lock spring 13 as shown in FIG. 15B so as to be moved to an upper side (an engine side) in the drawing even if the phase is unchanged. On the basis of the movement in the axial direction, the leading end portion of the wedge member 25 is brought into contact with the step portion 22 c of the vane 22 as shown in FIG. 15B so as to stop. If the cranking at a time of starting the engine is started, the sprocket 19 and the body 20 starts rotating by being driven by the crank shaft, however, the driving force is not transmitted from the vane 22 until the wedge member 25 comes to the state of being sandwiched between the drive member spark advance surface 20 a and the driven member phase lag surface 22 a, and the wedge member 16 stands still. In other words, the wedge member 25 necessarily executes the phase shift in the phase lag direction with respect to the vane 22 together with the body 20 until the wedge member 25 comes into contact with the driven member phase lag surface 22 a. In this process of the phase shift in the phase lag direction, the wedge member 25 is not moved in the axial direction, and executes the phase shift to the phase lag direction in a state in which the leading end portion is along the step portion 22 c. Next, if the leading end portion of the wedge member 25 passes through the range of the step portion 22 c, the wedge member 25 starts moving in the axial direction on the basis of the force of the lock spring 13 at the same time of executing the phase shift in the phase lag direction, and gets into a portion between the driven member spark advance surface 22 b and the driven member phase lag surface 22 a to some extent as shown in FIG. 15C so as to come to a state of being sandwiched by the drive member spark advance surface 20 a and the driven member phase lag surface 22 a. Thereafter processes are absolutely the same as the processes in FIGS. 14A to 14D, and the wedge member 25 doubling with the function of the intermediate member is finally sandwiched between the drive member phase lag surface 20 b and the driven member spark advance surface 22 b so as to comes to the intermediate position lock state. In other words, it is possible to automatically return to the phase lag direction toward the intermediate lock position. Accordingly, on the assumption that the wedge member 25 is the intermediate member in the regulating member for changing the phase in the spark advance direction, it is known that the inclination in the axial direction is not necessary in each of the contact surfaces in the regulating portion.
In the embodiments 1 and 2, the following features are provided.
The receiving portions brought into contact with the wedge members 16 and 25 are formed in bodies 2 and 20 corresponding to the first rotating body and the vanes 6 and 22 corresponding to the second rotating body. The receiving portions are constituted by the drive member spark advance surfaces 2 a and 20 a and the drive member phase lag surfaces 2 b and 20 b in the side of the bodies 2 and 20, and are constituted by the driven member phase lag surfaces 6 a and 22 a and the driven member spark advance surfaces 6 b and 22 b in the side of the vanes 6 and 22. The drive member spark advance surfaces 2 a and 20 a of the receiving portions in the side of the bodies 2 and 20, and the driven member phase lag surfaces 6 a and 22 a of the receiving portions in the side of the vanes 6 and 22 construct two contact surfaces in which the mutual intervals become narrowed in the inserting direction of the wedge members 16 and 25. At least any one contact surface of these contact surfaces is inclined with respect to the rotating direction (the inserting direction) of the first rotating body and the second rotating body, and is inclined with respect to the radiation direction from the center of rotation of the first rotating body and the second rotating body. In the embodiment 1 (FIG. 3), the drive member spark advance surface 2 a is inclined with respect to the direction of the rotating axis and the radiation direction, and the driven member phase lag surface 22 a is inclined with respect to the direction of the rotating axis and the radiation direction in the embodiment 2 (FIG. 13). The application line of the load applied to the drive member spark advance surface 2 a and the driven member phase lag surface 22 a, or the application line of the force which the wedge members 16 and 25 are applied from the drive member spark advance surface 2 a and the driven member phase lag surface 22 a becomes approximately vertical to the drive member spark advance surface 2 a and the driven member phase lag surface 22 a. As mentioned above, since the drive member spark advance surface 2 a and the driven member phase lag surface 22 a are inclined with respect to the direction of the rotating axis and the radiation direction, the distance from the center of rotation of the first rotating body and the second rotating body to the application line of the load or the force becomes smaller than the distance from the center of rotation of the first rotating body and the second rotating body to the application point of the load or the force. Accordingly, it is possible to make the force which the wedge members 16 and 25 are applied from the drive member spark advance surface 2 a and the driven member phase lag surface 22 a small, and it is possible to make the force pushing back the wedge members 16 and 25 in the take-out direction small.
It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.

Claims

1. A device for controlling a phase of a cam shaft in an internal combustion engine comprising:

a first rotating body rotating together with a sprocket;

a second rotating body provided coaxially in the first rotating body so as to control a phase angle and rotating together with the cam shaft; and

a fixing mechanism fixing phase angles of the first rotating body and the second rotating body,

wherein the fixing mechanism has a wedge member in which a wedge-shaped portion is formed,

wherein the first rotating body and the second rotating body have contact surfaces brought into contact with the wedge member, and

wherein at least any one of the contact surfaces of the first rotating body and the second rotating body is inclined with respect to a direction of a rotating axis of the first rotating body and the second rotating body, and is formed such that a distance from a center of rotation to an application line of a load applied to the contact surface is smaller than a distance from the center of rotation to an application point of the load on the contact surface.

2. A device for controlling a phase of a cam shaft in an internal combustion engine as claimed in claim 1, wherein the contact surface is provided so as to be inclined with respect to a radial direction from the center of rotation of the first rotating body and the second rotating body, whereby the distance from the center of rotation to the application line is smaller than the distance from the center of rotation to the application point.

3. A device for controlling a phase of a cam shaft in an internal combustion engine comprising:

a first rotating body rotating together with a sprocket;

wherein the fixing mechanism has a wedge member n which a wedge-shaped portion is formed,

wherein the first rotating body and the second rotating body have receiving portions brought into contact with the wedge member,

wherein the receiving portions of the first rotating body and the second rotating body are respectively provided with contact surfaces which are narrowed with each other in an inserting direction of the wedge member, and

wherein at least any one contact surface of the contact surfaces is inclined with respect to a direction of a rotating axis of the first rotating body and the second rotating body, and is inclined with respect to a radial direction from a center of rotation of the first rotating body and the second rotating body.

4. A device for controlling a phase of a cam shaft in an internal combustion engine as claimed in claim 3, wherein the fixing mechanism has an elastic member energizing the wedge member in the inserting direction to the contact surfaces, and a hydraulic mechanism generating a hydraulic force in a direction of pulling out the wedge member from the contact surfaces.

5. A device for controlling a phase of a cam shaft in an internal combustion engine as claimed in claim 3, wherein the first rotating body has an inner peripheral surface having a predetermined radius, the second rotating body has an outer peripheral surface having a predetermined radius, the first rotating body and the second rotating body are arranged such that the inner peripheral surface and the outer peripheral surface oppose to each other, the receiving portion of the first rotating body is provided in a side in which a diameter becomes larger than the inner peripheral surface, and the receiving portion of the second rotating body is provided in a side in which a diameter becomes smaller than the outer peripheral surface.

6. A device for controlling a phase of a cam shaft in an internal combustion engine as claimed in claim 1, wherein the first rotating body and the second rotating body have a second pair of contact surfaces which limit the phase angle in an inverse direction to a direction in which the phase angle is limited by a pair of contact surfaces provided in the first rotating body and the second rotating body and the wedge-shaped body, the second pair of contact surfaces limit the phase angle by being brought into contact via the intermediate member, and one of the second pair of contact surfaces is provided with a step portion enlarging a regulating range of the phase angle limited by the second pair of contact surfaces.

7. A device for controlling a phase of a cam shaft in an internal combustion engine as claimed in claim 1, wherein the contact surfaces are formed with an angle equal to or less than 11 degree with respect to an inserting direction of the wedge member.

8. A phase controlling device having a first rotating member and a second rotating member rotationally driven via the first rotating member, and controlling a phase angle corresponding to a relative rotational position between the first rotating member and the second rotating member,

wherein a drive member spark advance surface heading for a rotating direction of a whole of the device is formed in a drive side member in a power transmitting path from the first rotating member to the second rotating member,

wherein a driven member phase lag surface heading for an inverse direction to the rotating direction of the whole of the device is formed in a driven side member in the power transmitting path,

wherein one of the drive member spark advance surface and the driven member phase lag surface is inclined so as to head for an inner peripheral side within an axial vertical cross section with respect to a radial direction, and the other is inclined so as to head for an outer peripheral side within the axial vertical cross section,

wherein the device is provided with a wedge member sandwiched between the drive member spark advance surface and the driven member phase lag surface by the second rotating member changing the phase angle in the phase angle direction with respect to the first rotating member, an energizing means for energizing the wedge member to one of the directions of the rotating axes of the first rotating member and the second rotating member and a driving means for moving to the other of the directions of the rotating axes, and

wherein a distance between the drive member spark advance surface and the driven member phase lag surface in each of the axial vertical cross sections is made smaller to a cross section in an energizing direction by the energizing means.

9. A phase controlling device as claimed in claim 8, wherein the drive member spark advance surface is arranged in one of inner and outer sides of a cylinder surface having a predetermined radius, and the driven member phase lag surface is arranged in the other side.