Valve timing control device having vane rotor

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and incorporates herein by reference Japanese Patent Application No. 2004-144007 filed on May 13, 2004.

FIELD OF THE INVENTION

The present invention relates to a valve timing control device, and is preferably applied to a valve timing control device that changes opening and closing timing of at least one of an intake valve and an exhaust valve of a vehicular internal combustion engine in accordance with an operating condition, for example.

BACKGROUND OF THE INVENTION

A vane-type valve timing control device disclosed in JP-A-2001-82278 hydraulically controls a valve timing of at least one of an intake valve and an exhaust valve in accordance with a phase difference caused by a relative rotation between a chain sprocket and a camshaft. The vane-type valve timing control device drives the camshaft serving as a driven shaft via a driving force transmission member such as a timing pulley, which synchronously rotates with a crankshaft serving as a driving shaft, and the chain sprocket. In the vane-type valve timing control device, an initial phase thereof in such an idling condition has to be on the advanced angular side opposite to load torque, which urges the vane rotor to the retarded angular side when the camshaft is driven.

The valve timing control device disclosed in JP-A-2001-82278 includes a housing, a vane rotor, and an assist spring. The housing rotates with the driving force transmission member such as the chain sprocket. The vane rotor rotates with the camshaft, and the vane rotor is capable of rotating within an accommodation chamber formed in the housing. The assist spring applies force against the vane rotor in the advanced direction. The assist spring is constructed of a torsion coil spring. Both ends of the torsion coil spring are arranged along the axial direction. One end of both the ends of the torsion coil spring is secured to the vane rotor. The other end of the torsion coil spring is secured to the housing that accommodates the vane rotor such that the vane rotor is rotatable in both the advanced direction and the retarded direction.

However, in the above structure disclosed in JP-A-2001-82278, the other end of the torsion coil spring, which axially extends, is secured to a spring securing portion on the side of the housing, and the spring securing portion overhangs to the frontside of the engine. Accordingly, the length of the valve timing control device, that is, the length of the engine may be enlarged.

On the contrary, the other end of the torsion coil spring may be radially extended outwardly from the outer circumferential periphery of the torsion coil spring. The housing includes island portions that are circumferentially arranged in the accommodation chamber formed in the housing to receive the vane rotor. A hooking member such as a pin is secured to the island portion by pressure insertion or the like, so that the other end of the torsion coil spring is capable of hooking to the pin.

Each of the island portions, which are circumferentially arranged in the accommodation chamber that receives the vane rotor, is preferably reduced in width relative to the rotative direction thereof to enlarge a range of advanced angle of the vane rotor. Here, a bolt shank of a bolt is capable of being inserted through a hole, which is formed in the island portion. The bolt serves as a securing member to secure the driving force transmission member such as the chain sprocket to the housing. When the torsion coil spring, in which the other end radially outwardly extends, is applied to the valve timing control device, the bolt, specifically a bolt head and the pin may be hard to be arranged within the island portion, which is preferably formed small in width relative to the rotative direction.

SUMMARY OF THE INVENTION

In view of the foregoing problems, it is an object of the present invention to produce a valve timing control device that includes a vane rotor, a housing, a torsion coil spring urging the vane rotor in the advanced direction or in the retarded direction relative to the housing, in a manner that a range of an advanced angle between island portions, which are circumferentially arranged within the accommodation chamber receiving the vane rotor, can be enlarged. The valve timing control device includes a hooking member, to which an end of the torsion coil spring hooks, and a securing member such as a screwing member, in a manner that the hooking member and the securing member can be arranged in the island portion.

It is another object of the present invention to produce a valve timing control device that includes the vane rotor, the housing, the torsion coil spring urging the vane rotor in the advanced direction or in the retarded direction relative to the housing, in a manner that the range of the advanced angle between the island portions of the vane rotor can be enlarged, besides the hooking member, to which the end of the torsion coil spring hooks, and the securing member can be arranged in the island portion, furthermore, the valve timing control device is capable of being downsized in the axial direction.

According to the present invention, a valve timing control device is provided to a driving force transmission system, which transmits driving force from a driving shaft of an internal combustion engine to a driven shaft. The driven shaft opens and closes at least one of an intake valve and an exhaust valve. The valve timing control device controls an opening timing and a closing timing of at least one of the intake valve and the exhaust valve. The valve timing control device includes a housing member, a vane rotor member, a torsion coil spring, a hooking member, and a securing member.

The housing member rotates with one of the driving shaft and the driven shaft. The housing member defines multiple accommodation chambers that include multiple island portions to be adjacent to each other in a circumferential direction of the accommodation chambers. The vane rotor member is accommodated in the accommodation chambers. The vane rotor member includes a vane portion, which is restricted in rotation within a predetermined rotative angular range defined by the plurality of island portions.

The torsion coil spring has one end that hooks on the housing member. The torsion coil spring has another end that hooks to the vane rotor member. The torsion coil spring biases the vane rotor member to one of an advanced angular side and a retarded angular side with respect to the housing member. The hooking member circumferentially hooks on the one end of the torsion coil spring. The one end of the torsion coil spring extends to a radially outer side. The securing member secures a member of the driving force transmission system to the housing member.

The hooking member and the securing member are provided to at least one of the island portions. The hooking member and the securing member are arranged in this order along a direction, in which resilience of the torsion coil spring works.

Thereby, the width of the island portion in a rotative angular direction can be decreased. Thus, the advanced angular range, in which the vane portion is rotatable between corresponding island portions in the circumferential direction, can be further increased.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a schematic view showing a valve timing control device according to an embodiment of the present invention;

FIG. 2 is a partially perspective front view showing the valve timing control device according to the embodiment;

FIG. 3 is a front view showing the valve timing control device taken along the line III-III in FIG. 1;

FIG. 4A is a segmentary view showing a condition, in which a torsion coil spring hooks to a pin in the valve timing control device, and FIG. 4B is a side view showing the condition, in which the torsion coil spring hooks to the pin according to the embodiment;

FIG. 5A is a segmentary view showing a condition, in which a torsion coil spring hooks to a pin in a valve timing control device, and FIG. 5B is a side view showing the condition, in which the torsion coil spring hooks to the pin, according to a first comparative example; and

FIG. 6A is a segmentary view showing a condition, in which a torsion coil spring hooks to a pin in a valve timing control device, and FIG. 6B is a side view showing the condition, in which the torsion coil spring hooks to the pin, according to a second comparative example.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(Embodiment)

As shown in FIG. 1, a valve timing control device 1 includes a shoe housing 10 and a sprocket portion 30. The shoe housing 10 serves as a housing member. The sprocket portion 30 is constructed of a bush portion (bush) 32 and a sprocket 33. The bush 32 receives a camshaft 4, which serves as a driven shaft, therethrough. The sprocket 33 has gears 33b on the outer circumferential periphery thereof. Driving force is transmitted from a crankshaft 210 to the sprocket 33 via a driving force transmission member 211 such as a timing chain 211 or a timing belt 211, so that the sprocket 33 rotates synchronously with the crankshaft 210. In this embodiment, a timing chain 211 is used as the driving force transmission member. The crankshaft 210 serves as a driving shaft of an internal combustion engine 300.

Driving force is transmitted from the sprocket portion 30, specifically, from the sprocket 33 to the camshaft 4, so that the camshaft 4 opens and closes an exhaust valve 201. The camshaft 4 is capable of rotating at a predetermined phase difference with respect to the sprocket portion 30. The timing chain 211 and the sprocket portion 30 construct the driving force transmission member for a driving force transmission system. The driving force transmission member transmits driving force of the crankshaft 210 to the camshaft 4. The sprocket 33 and the bush 32 are secured using a bolt 34 to integrally construct the sprocket portion 30. The sprocket portion 30 and the camshaft 4 rotate in the clockwise direction (advanced direction) when being viewed from the left direction in FIG. 1. The shoe housing 10 and the sprocket portion 30 construct a rotative body, which rotates synchronously with the crankshaft 210, on the driving side. The shoe housing 10 and the sprocket portion 30 are coaxially secured to each other using a bolt 31.

The shoe housing 10 is constructed of a substantially cylindrical circumferential wall (shoe housing portion) 11 and a substantially flat plate shaped front plate (front plate portion) 12. The circumferential wall 11 and the front plate 12 are secured to the sprocket portion 30 using the bolt 31 to be integral in a substantially bowl shape. The circumferential wall 11 and the front plate 12 are not limited to be individual members, and may be an integral member.

As shown in FIGS. 2, 3, the shoe housing 10, specifically, the circumferential wall 11 includes island portions (shoes) 10a, 10b, 10c, 10d that are formed in a substantially trapezoid shape relative to the axial direction of the shoe housing 10. The shoes 10a, 10b, 10c, 10d are arranged along the circumferential direction of the circumferential wall 11 at substantially regular intervals. In this embodiment, the circumferential wall 11 is formed with shoes 10a, 10b, 10c, 10d that are arranged in an order from the shoe 10a, into which a pin (hooking member) 22 is press-inserted, the shoe 10b, the shoe 10c, and the shoe 10d along the clockwise direction.

The shoes 10a, 10b, 10c, 10d form four spaces therebetween along the circumferential direction thereof. As referred to FIG. 3, the four spaces among the shoes 10a, 10b, 10c, 10d form accommodation chambers 14. Each accommodation chamber 14 accommodates each of vane portions (vanes) 50a, 50b, 50c, 50d serving as vane rotor members. Each shoe 10a, 10b, 10c, 10d has an inner wall surface that is respectively formed in a substantially arc shape in cross section. The inner wall surface of each shoe 10a, 10b, 10c, 10d partitions each accommodation chamber 14.

The vanes 50a, 50b, 50c, 50d, which are circumferentially arranged at substantially regular intervals, construct a rotor 50. Each vane 50a, 50b, 50c, 50d is accommodated in each accommodation chamber 14, such that each vane 50a, 50b, 50c, 50d partitions each accommodation chamber 14 into a retarded angular hydraulic chamber and an advanced angular hydraulic chamber. The rotor 50 and the vanes 50a, 50b, 50c, 50d construct a vane rotor member. Each vane 50a, 50b, 50c, 50d rotates within each accommodation chamber 14, i.e., between shoes, while being restricted in rotative angle within a predetermined rotative angular range (advanced angular range) Δθ.

As referred to FIG. 1, a positioning pin 51 is provided between the rotor 50 and the camshaft 4 for positioning the valve timing control device 1 with respect to the camshaft 4. The rotor 50 is positioned to be in a positioning angle using the positioning pin 51, subsequently, the rotor 50 is secured integrally with the camshaft 4 using a bolt 20. The rotor 50, the vanes 50a, 50b, 50c, 50d, and the positioning pin 51 construct a rotative body, which rotates synchronously with the camshaft 4 on the driven side. The camshaft 4, the rotor 50, the vanes 50a, 50b, 50c, 50d are capable of rotating coaxially with respect to the shoe housing 10 and the sprocket portion 30.

As referred to FIG. 3, each of shoe seals 53 engages with each outer periphery of each vane 50a, 50b, 50c, 50d. Each outer circumferential wall of each vane 50a, 50b, 50c, 50d and each inner circumferential wall of the circumferential wall 11 forms a small clearance therebetween. The shoe seal 53 restricts working fluid from leaking between the retarded angular hydraulic chamber and the advanced angular hydraulic chamber thorough the clearance. The shoe seal 53 is urged onto the inner circumferential wall of the circumferential wall 11 by resilience of a leaf spring (not shown). Each of shoe seals 53 is also respectively provided into each clearance formed between the outer circumferential periphery of the rotor 50 and each inner wall of the shoes 10a, 10b, 10c, 10d of the inner circumferential wall of the circumferential wall 11.

As referred to FIGS. 1, 3, a stopper piston 71, which is in a substantially cylindrical shape, is accommodated in the vane 50d to be slidable along the axial direction of the camshaft 4. An engaging ring 72 is press-inserted into a recess formed in the sprocket portion 30, specifically formed in the bush 32. The stopper piston 71 is capable of engaging with the engaging ring 72. A spring 73 urges the stopper piston 71 to the side of the engaging ring 72. The stopper piston 71 has a tip end that is capable of engaging with the engaging ring 72, when the vane rotor 50 is at the most advanced angular position with respect to the shoe housing 10. The vane rotor 50 is restricted from rotating with respect to the shoe housing 10, when the stopper piston 71 engages with the engaging ring 72. When the vane rotor 50 rotates from the most advanced angular position to the retarded angular side with respect to the shoe housing 10, the stopper piston 71 is circumferentially displaced relative to the engaging ring 72, so that the stopper piston 71 does not engage with the engaging ring 72. Here, the stopper piston 71 may be accommodated in a guide ring, which is press-inserted into the vane 50d (FIG. 3), such that the stopper piston 71 is slidable along the axial direction of the camshaft 4. The stopper piston 71 and the engaging ring 72 construct a rotative angular phase latching means 70. The rotative angular phase latching means 70 is capable of latching the shoe housing 10 onto the vane rotor 50 at an intermediate position in the predetermined rotative angular range. That is, the rotative angular phase latching means 70 is capable of latching the rotative body, which is on the driving side, onto the rotative body, which is on the driven side, at the intermediate position in the predetermined rotative angular range. In this embodiment, the intermediate position is the most advanced angular position in the predetermined rotative angular range.

The shoe 10a and the vane 50a form an advanced angular hydraulic chamber therebetween. The shoe 10b and the vane 50b form an advanced angular hydraulic chamber therebetween. The shoe 10c and the vane 50c form an advanced angular hydraulic chamber therebetween. The shoe 10d and the vane 50d form an advanced angular hydraulic chamber therebetween.

The shoe 10b and the vane 50a form a retarded angular hydraulic chamber therebetween. The shoe 10c and the vane 50b form a retarded angular hydraulic chamber therebetween. The shoe 10d and the vane 50c form a retarded angular hydraulic chamber therebetween. The shoe 10a and the vane 50d form a retarded angular hydraulic chamber therebetween.

As referred to FIG. 1, hydraulic paths 91, 92 respectively connect to a switching valve 100 via hydraulic paths 93, 94. A hydraulic supply path 101 is connected to a hydraulic pump 102, so that oil is supplied from the hydraulic pump 102 through the hydraulic supply path 101. A hydraulic exhaust path 103 opens to a drain 104, so that oil is exhausted toe the drain 104 through the hydraulic exhaust path 103. The hydraulic pump 102 pumps working fluid from the drain 104, so that the hydraulic pump 102 supplies the working fluid to respective hydraulic chambers through the switching valve 100. The switching valve 100 is a guide valve with 4 ports. The switching valve 100 has a valve member 105 that is urged by a spring 106 to one side. The valve member 105 reciprocates by energizing and de-energizing a solenoid 107. The solenoid 107 is controlled in emerging condition by an ECU serving as a control means (not shown). The valve member 105 reciprocates in the switching valve 100, so that a combination of communication and a combination of blockade can be switched among the hydraulic paths 93, 94, the hydraulic supply path 101, and the hydraulic exhaust path 103. With the above structure of hydraulic paths, working fluid can be supplied from the hydraulic pump 102 to the advanced angular hydraulic chamber, the retarded angular hydraulic chamber, and a hydraulic chamber 121 (FIG. 1), besides, hydraulic fluid can be exhausted from respective hydraulic chambers to the drain 104.

A spring (torsion coil spring) 21 is accommodated in a substantially annular accommodating portion formed in a spring plate 29. As referred to FIGS. 1, 2, the spring 21 has one end 21a that hooks to the pin 22, which protrudes from the front plate 12. As referred to FIGS. 2, 3, the spring 21 has the other end 21b that hooks to a securing groove 54a, which is formed in a bolt seat face 54. The camshaft 4 receives load torque when the camshaft 4 drives the exhaust valve 201. The load torque applied to the camshaft 4 fluctuates to both the positive side and the negative side thereof. The load torque applied to the positive side biases the rotor 50 to the retarded angular side with respect to the shoe housing 10. The load torque applied to the negative side biases the rotor 50 to the advanced angular side with respect to the shoe housing 10. Load torque works to the positive side, i.e., to the retarded angular side, on average. Resiliency of the spring 21 works as torque that rotates the rotor 50 to the advanced angular side with respect to the shoe housing 10. The spring 21 applies torque to the rotor 50 in the advanced angular direction, and the torque applied by the spring 21 to the rotor 50 becomes maximum when the rotor 50 is in the most retarded angular position with respect to the shoe housing 10. As the rotor 50 moves to the advanced angular direction with respect to the shoe housing 10, the torque, which is applied to the rotor 50 by the spring 21, decreases. The spring 21 serves as an advanced angular assisting means that urges the rotor 50 to the advanced angular side, i.e., the rotative angular direction.

The pin 22 is secured to the front plate 12 (FIG. 2) and the circumferential wall 11, specifically, the shoe 10a by press-insertion or the like. Each shoe 10a, 10b, 10c, 10d has a bolt hole 11t, through which the bolt 31 is capable of being inserted. The shoe 10a has a pin hole 11p, through which the pin 22 is press-inserted, in addition to the bolt hole 11t.

Each circumferential wall of each shoe 10b, 10c, 10d restricts the vane in rotative angle. Each circumferential wall of each shoe 10b, 10c, 10d has a width that is shown by a rotative angle range A2 in FIG. 2. The circumferential wall of the shoe 10a also restricts the vane in rotative angle. The circumferential wall of the shoe 10a has a width that is shown by a rotative angle range A1. The pin hole 11p is formed in the shoe 10a in addition to the bolt hole 11t, accordingly, A1 becomes greater than A2.

The bolt 31 includes a bolt shank 31a and a bolt head 31b. The bolt shank 31a has a thread on the tip end thereof. The bolt head 31b transmits screw torque, which is applied from the outside, to the bolt shank 31a. The end face of the shoe housing 10, specifically, the surface of the front plate 12 forms a seat face of the bolt head 31b. The pin 22 includes a pin shank (shank portion) 22a and a pin head (disc portion) 22b. The pin shank 22a is press-inserted into the shoe 10a, specifically, into the pin hole 11p, so that the pin 22 is secured to the shoe 10a. The pin head 22b, which is in a disc shape, is formed to be larger than the pin shank 22a in diameter. Thereby, the pin head 22b restricts the one end 21a of the spring 21 from being detached from the pin shank 22a of the pin 22 along the axial direction of the pin 22 due to spring back of the spring 21 or the like.

The bolt 31 serves as a securing member (screwing member) that secures the shoe housing 10, specifically, the circumferential wall 11 and the front plate 12 to the sprocket portion 30. The pin 22 serves as a hooking means such that the one end 21a, which radially extends from the spring 21, hooks to the pin 22 in the circumferential direction.

As show in FIGS. 4A, 4B, the pin 22 and the bolt 31 are arranged in the shoe 10a. The pin 22 and the bolt 31 are arranged in this order along the direction, in which resilience (spring force) of the spring 21 works. Here, the spring 21 resiliently urges the rotor 50 to the advanced angular side in the rotative angular direction.

Preferably, the pin 22 and the bolt 31 are arranged in the shoe 10a such that the radially outer periphery of the pin shank 22a of the pin 22 contacts with the radially outer periphery of the bolt head 31b of the bolt 31. Thereby, the width, i.e., the angle A1 of the shoe 10a in the rotative direction can be reduced. Thus, the shoe 10a can be downsized in the rotative direction. Thereby, an advanced angular range of the vanes 50a, 50b, 50c, 50d can be further increased within the respective spaces formed among the shoes 10a, 10b, 10c, 10d. That is, an advanced angular range of the vane rotor member, which is constructed of the rotor 50 and the vanes 50a, 50b, 50c, 50d, can be further increased within the spaces such as the space between the shoes 10a, 10b and the space between the shoes 10a, 10d.

Furthermore, preferably, the pin head 22b contacts with the bolt head 31b in the axial direction. Thereby, a height of a member, which protrudes from the seat face of the front plate 12, is limited to a height, which is a sum of the height of the bolt head 31b and the height of the pin head 22b. Therefore, the height of the member, which protrudes from the end face of the shoe housing 10, specifically, the height of the member, which protrudes from the surface of the front plate 12 in a substantially axial direction, can be reduced to a small degree. Thus, the valve timing control device 1 can be downsized relative to the axial direction.

As follows, a first comparative example and a second comparative example are described in reference to FIGS. 5A, 5B, 6A, 6B.

In the first comparative example shown in FIG. 5A, the pin 22 and the bolt 31 are provided to the shoe 10a. Specifically, the bolt 31 and the pin 22 are arranged in this order along the direction, in which resilience (spring force) of the spring 21 works. As shown in FIGS. 5A, 5B, the pin 22 and the bolt 31 are arranged in the shoe 10a such that the radially outer periphery of the pin shank 22a contacts with the radially outer periphery of the bolt head 31b. Thereby, the width A1 of the shoe 10a in the rotative direction can be reduced.

However, the pin shank 22a needs to be extended from the bolt head 31b by the diameter φC of the spring 21 in the axial direction thereof to contact the one end 21a of the spring 21 circumferentially with the pin shank 22a. Here, the one end 21a of the spring 21 does not circumferentially contact with the bolt head 31b. In this first comparative example, the axial gap between the bolt head 31b and the pin head 22b is set to be B (B>φC), for example. In this case, the height of the pin shank 22a is extended by the height B, compared with the structure in the embodiment described above.

In the first comparative example, the pin shank 22a needs to be extended by at least the diameter φC of the spring 21, compared with the embodiment described above. Accordingly, a length, by which a member protrudes from the end face of the shoe housing 10 substantially along the axial direction, may increase.

On the contrary, as shown in FIG. 6A, in the second comparative example, the pin 22 and the bolt 31 are provided to the shoe 10a. Specifically, the bolt 31 and the pin 22 are arranged in this order along the direction, in which resilience (spring force) of the spring 21 works, similarly to the first example. As shown in FIGS. 6A, 6B, the pin 22 and the bolt 31 are arranged in the shoe 10a such that the radially outer periphery of the pin shank 22a does not contact with the radially outer periphery of the bolt head 31b. That is, the radially outer periphery of the pin shank 22a is apart from the radially outer periphery of the bolt head 31b by a predetermined distance. Thereby, a length, by which the pin 22, specifically, the pin head 22b protrudes from the end face of the shoe housing 10 substantially along the axial direction, can be reduced to small degree.

However, in the second comparative example, the spring 21 needs to be hooked to the pin shank 22a of the pin 22, which is assembled to the shoe 10a, through a gap D between the pin head 22b and the bolt head 31b. Accordingly, a shortest gap between the pin 22 and the bolt 31 along the circumferential direction needs to be larger than the diameter φC of the spring 21. That is, a gap D, which is formed between the radially outer periphery of the pin head 22b and the radially outer periphery of the bolt head 31b, needs to be larger than the diameter φC of the spring 21.

In the second comparative example, when the gap D is set to be greater than the diameter φC of the spring 21, for example, the width A3 (A3>A1) of the shoe 10a increases by the gap D in the rotative direction, compared with the embodiment described above.

As follows, an operation of the valve timing control device having the above structure is described. As shown in FIG. 1, when the engine 300 is normally operated, working fluid is supplied to the hydraulic chamber 121, which is arranged on the outer circumferential side of the stopper piston 71. Thereby, hydraulic pressure works onto the stopper piston 71, so that the stopper piston 71 is pulled out of the engaging ring 72. In this situation, the vanes 50a, 50b, 50c, 50d, and the rotor 50 are rotatable relative to the shoe housing 10 and the sprocket portion 30. Hydraulic pressure applied to each hydraulic chamber is controlled, so that a phase difference of the camshaft 4 is controlled with respect to the crankshaft 210.

Even when the engine 300 is restarted, working fluid is not supplied to the hydraulic chamber 121, which is arranged on the outer circumferential side of the stopper piston 71, before working fluid is supplied to the advanced angular hydraulic chamber and the retarded angular hydraulic chamber. Therefore, the stopper piston 71 is maintained to be engaging with the engaging ring 72, so that the camshaft 4 is maintained at the most advanced angular position with respect to the crankshaft 210.

Working fluid is supplied to the advanced angular hydraulic chamber or the retarded angular hydraulic chamber, and working fluid is supplied to the hydraulic chamber 121, so that the stopper piston 71 receives force in the left direction in FIG. 1. Thereby, the stopper piston 71 is pulled out of the engaging ring 72 against resilience of the spring 73. As a result, restriction between the rotor 50 and the shoe housing is released, so that the vane rotor 50 rotates relative to the shoe housing 10 by hydraulic force working in the advanced angular hydraulic chamber and the retarded angular hydraulic chamber. Thus, a phase difference of the camshaft 4 can be adjusted relative to the crankshaft 210.

Next, an effect of the structure of the above embodiment is described.

The valve timing control device 1 includes a shoe housing 10, the vane rotor member 50, 50a, 50b, 50c, 50d, and the spring 21.

The vanes 50a, 50b, 50c, 50d are restricted in rotation angle within a predetermined rotation angular range, i.e., within an advanced angular range between the shoes 10 such as the shoes 10a, 10b or the shoes 10a, 10d formed in the shoe housing 10, specifically, formed in the circumferential wall 11.

The one end 21a of the spring 21 hooks on the shoe housing 10. The other end 21b of the spring 21 hooks on the vane rotor member 50, 50a, 50b, 50c, 50d. Thereby, the spring 21 biases the vane rotor member 50, 50a, 50b, 50c, 50d to the advanced angular side or the retarded angular side with respect to the shoe housing 10.

The valve timing control device 1 further includes the pin 22 and the bolt 31. The one end 21a of the spring 21 extends to the radially outer side. The one end 21a of the spring 21 hooks on the pin 22 in the circumferential direction. The bolt 31 secures the sprocket portion 30 with the shoe housing 10. The pin 22 and the bolt 31 are arranged within the shoe 10a in this order along the direction, in which resilience of the spring 21 is applied. Thereby, the advanced angular range of the vane rotor member 50, 50a, 50b, 50c, 50d can be increased between the corresponding shoes, besides, the pin 22 and the bolt 31 can be arranged in the shoe 10a. Specifically, each vane 50a, 50b, 50c, 50d can be rotated between two of the corresponding shoes 10a, 10b, 10c, 10d in the circumferential direction within the predetermined rotation angular range. In the above structure, the predetermined rotation angular range can be increased, while the pin 22 and the bolt 31 can be provided to the shoe 10a.

In the structure of the above embodiment, the pin 22 and the bolt 31 are preferably arranged in the shoe 10a in such a manner that the radially outer periphery of the pin shank 22a and the radially outer periphery of the bolt head 31b contact with each other. Thereby, the width Al of the shoe 10a in the rotative angular direction can be decreased. Thus, the advanced angular range, in which each vane 50a, 50b, 50c, 50d is rotatable between two of the corresponding shoes 10a, 10b, 10c, 10d in the circumferential direction, can be further increased.

The arrangement of the pin 22 and the bolt 31 in the shoe 10a is not limited to the arrangement, in which the radially outer peripheries of the pin shank 22a and the bolt head 31b contact with each other for increasing the advanced angular range, in which each vane 50a, 50b, 50c, 50d are rotatable between two of the corresponding shoes 10a, 10b, 10c, 10d in the circumferential direction.

Any radially outer periphery of the pin 22 may contact with the radially outer periphery of the bolt head 31b. For example, the radially outer periphery of the pin head 22b may contact with the radially outer periphery of the bolt head 31b. Even in this structure, the pin 22 and the bolt 31 are arranged within the shoe 10a in such an order from the pin 22 to the bolt 31 along resilient force of the spring 21. Therefore, the advanced angular range, in which each vane 50a, 50b, 50c, 50d is rotatable between two of the corresponding shoes 10a, 10b, 10c, 10d in the circumferential direction, can be further increased, while the pin 22 and the bolt 31 can be provided to the shoe 10a.

Furthermore, in the above embodiment, preferably, the pin head 22b axially contacts with the bolt head 31b. Thereby, the height of the member, which protrudes from the end face of the front plate 12, specifically, from the seat face of the front plate 12, is limited to the height, which is the sum of the height of the bolt head 31b and the height of the pin head 22b. Therefore, the height of the member, which protrudes from the end face of the shoe housing 10 can be reduced. Thus, the valve timing control device 1 can be downsized relative to the axial direction.

Furthermore, in the above embodiment, preferably, the shoe housing 10 includes the circumferential wall 11, which includes the shoes 10a, 10b, 10c, 10d, and the front plate 12, which is provided to a tip end of the circumferential wall 11. Besides, the bolt head 31b of the bolt 31 axially protrudes from the front plate 12, so that the surface of the front plate 12, i.e., the end face of the shoe housing 10 can serve as the seat face of the bolt head 31b. Thereby, the shoes 10a, 10b, 10c, 10d can be downsized, so that the advanced angular range of the vane rotor members 50, 50a, 50b, 50c, 50d can be easily enlarged between the corresponding shoes, compared with a structure, in which a seat face of the bolt head 31b is formed in the circumferential wall 11.

When a seat face of the bolt head 31b is formed in the circumferential wall 11, specifically, in the shoe 10a, for example, the shoe 10a needs to be enlarged to form a seat face, which has a sufficient area to axially receive the bolt head 31b. Accordingly, when a seat face of the bolt head 31b is formed in the shoe 10a, the shoe 10a may be enlarged, and the advanced angular range may be decreased.

According to a conventional structure disclosed in JP-A-2002-295210, when a seat face of a bolt head is formed in a circumferential wall, a radially outer wall surface needs to be provided to the circumferential wall to secure a gap between the circumferential wall and the radially outer periphery of the bolt head. The radially outer wall surface axially extends from the seat face to secure a predetermined gap from the radially outer periphery of the bolt head. Accordingly, shoes are occupied by the size of the radially outer wall surface. Furthermore, the shoes need to be enlarged by the wall thickness needed for forming the radially outer wall surface. Accordingly, the shoes are restricted from being downsized due to the radially outer wall surface for securing the gap between the circumferential wall and the radially outer periphery of the bolt head. Therefore, this conventional structure cannot be downsized compared with the structure in the above embodiment.

(Other Embodiment)

In the above embodiment, the valve timing control device 1 controls the difference of rotational phase of the camshaft 4, which operates the exhaust valve 201, with respect to the crankshaft 210. However, the valve timing control device 1 may control the difference of rotational phase of the camshaft 4, which operates an intake valve 202, with respect to the crankshaft 210.

In the above embodiment, the bolt 31 is used as the member that secures the shoe housing 10 with the sprocket portion 30, which is a member of the driving force transmission system. However, this member is not limited to a screwing member such as a bolt, and the member may be any securing member, as long as the member secures the shoe housing 10 with the sprocket portion 30.

The structures of the above embodiments and the examples can be combined as appropriate.

Various modifications and alternations may be diversely made to the above embodiments without departing from the spirit of the present invention.

Valve timing control device having vane rotor

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