Valve timing control device of internal combustion engine

Abstract

To provide a valve timing control device of an internal combustion engine which enables improvement of rigidity of a rotor and provides flexibility of the layout of a radial oil passage.SOLUTION: A vane rotor 9 includes: a rotor 13 fixed to a cam shaft 2 by a cam bolt 8; four vanes which partition a working chamber in a housing into four advance angle hydraulic chambers and four retard hydraulic chambers; second axial oil holes 21 formed along a rotation axis direction in the rotor and respectively communicating with cam shaft oil passages 19; and second radial oil passages 23 communicating with the second axial oil holes and the four advance angle hydraulic chambers. In the axial oil hole 21, an inner diameter d is formed so as to be larger than an inner diameter d1 of a cam shaft oil passage and an axis position P is offset toward the radial outer side from an axis position P1 of the cam shaft oil passage.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a valve timing control device for an internal combustion engine. [Background technology]

[0002] The conventional valve timing control device described in the following Patent Document 1 includes a timing sprocket to which a rotational force is transmitted from a crankshaft, a cylindrical housing connected to the timing sprocket, a vane rotor provided inside the housing so as to be relatively rotatable, a working chamber inside the housing is divided by the vane rotor into two hydraulic chambers, a retard hydraulic chamber and an advance hydraulic chamber, and a hydraulic circuit that controls the supply and discharge of control hydraulic pressure from an oil pump to the retard hydraulic chamber and the advance hydraulic chamber. The vane rotor is fixed to one end of the camshaft in the rotation axis direction by a cam bolt. The hydraulic circuit includes a plurality of camshaft oil passages for retarding and advancing formed axially within one end of the camshaft, a plurality of axial holes for retarding and advancing formed along the internal axial direction of the vane rotor, one end of which communicates with each of the camshaft oil passages, a pair of retard side oil passages formed in an L shape within the rotor, one end of which communicates with the retard side axial hole and the other end of which communicates with the two retard hydraulic chambers, and a pair of advance side oil passages formed radially within the rotor, one end of which communicates with the advance side axial hole and the other end of which communicates with the two advance hydraulic chambers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-194442 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, in the conventional valve timing control device, the retard side oil passage is formed inside the rotor in an L-shape and the advance side oil passage is formed straight along the radial direction inside the rotor, but the inner diameters of the multiple axial holes of the rotor are formed to be the same size as the inner diameter of the camshaft oil passage and the inner diameters of the retard side and advance side oil passages, and are fixed.

[0005] As a result, the freedom of layout of each oil hole and each oil passage is restricted, and the layout of the retard side oil passage and the advance side oil passage, in particular, cannot be freely changed due to different structures of the valve timing control device or differences in the outer diameter of the cam bolt.

[0006] One object of the present invention is to provide a valve timing control device for an internal combustion engine which allows for greater freedom in the layout of radial oil passages by enlarging the inner diameter of the axial oil hole formed inside the rotor and offsetting it radially outward from the camshaft oil passage. [Means for solving the problem]

[0007] In a preferred embodiment of the present invention, there is provided a compressor having a housing to which a rotational force from a crankshaft is transmitted and which has an operating chamber therein, and a vane rotor disposed inside the housing so as to be capable of relative rotation, The vane rotor includes a rotor fixed to a camshaft by a cam bolt; a plurality of vanes provided on the rotor and dividing the working chamber into a plurality of first hydraulic chambers and a plurality of second hydraulic chambers; a plurality of axial oil holes formed inside the rotor along the direction of the rotational axis of the rotor and communicating with a plurality of camshaft oil passages formed in the camshaft, the plurality of axial oil holes having inner diameters larger than the inner diameters of the camshaft oil passages and having central positions offset radially outwardly with respect to the camshaft oil passages; and first radial oil passages communicating with each of the axial oil holes, each having a straight end that opens into one of the first hydraulic chambers and a bent other end that opens into the other first hydraulic chamber. Effect of the Invention

[0008] According to a preferred embodiment of the present invention, it is possible to ensure an appropriate state of communication between the axial oil hole in the rotor and the camshaft oil passage, and to improve the degree of freedom in layout of the first radial oil passage. [Brief description of the drawings]

[0009] [Figure 1] 1 is a vertical sectional view showing an embodiment of a valve timing control device according to the present invention, including a hydraulic circuit. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1, illustrating a state in which a vane rotor of the valve timing control device is relatively rotated to a most retarded position. [Diagram 3] 2 is a cross-sectional view taken along line BB in FIG. 1 , showing a state in which the vane rotor is relatively rotated to a most advanced position. [Figure 4] 4 is a cross-sectional view of a main portion showing a relationship between a second camshaft oil passage, a second axial oil hole, and a second radial oil passage in the embodiment. FIG. [Diagram 5] 6 is a schematic diagram showing a state in which a second camshaft oil passage is connected to a second axial oil hole and a second radial oil passage on an advance side in the embodiment. FIG. [Figure 6] 6 is a schematic diagram showing flow characteristics of oil that has flowed from the second camshaft oil passage shown in FIG. 5 into a second axial oil hole and a second radial oil passage. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment in which a valve timing control device for an internal combustion engine according to the present invention is applied to the exhaust valve side will be described with reference to the drawings. The internal combustion engine is, for example, an in-line four-cylinder engine, and each cylinder has two intake valves and two exhaust valves.

[0011] FIG. 1 is a longitudinal sectional view showing an embodiment of a valve timing control device including a hydraulic circuit according to the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1 showing a state in which a vane rotor of the valve timing control device has relatively rotated to a most retarded position, and FIG. 3 is a sectional view taken along line BB in FIG. 1 showing a state in which the vane rotor has relatively rotated to a most advanced position.

[0012] As shown in Figures 1 to 3, the valve timing control device comprises a timing sprocket (hereinafter referred to as the sprocket) 1 that is rotated by the engine crankshaft via a timing chain, an intake side camshaft 2 that is arranged to be rotatable relative to sprocket 1, a phase change mechanism 3 that is disposed between sprocket 1 and camshaft 2 and converts the relative rotational phase between sprocket 1 and camshaft 2, and a hydraulic circuit 4 that operates the phase change mechanism 3.

[0013] The sprocket 1 is made of sintered metal formed by compressing and heating iron-based metal powder into a thick disk shape, and has gear parts 1a around the outer periphery of which a timing chain is wound. The sprocket 1 also has a support hole 1b formed in the center, into which one end 2a of a camshaft 2 in the rotation axis direction is rotatably inserted.

[0014] Sprocket 1 has four female threaded holes formed at equally spaced positions on the outer periphery, into which four bolts (not shown) are screwed. Sprocket 1 also has a pin 1c protruding from a predetermined position on the inner surface opposite to camshaft 2 in the rotation axis direction, as shown in Fig. 2, for positioning with housing main body 7 (described later). Sprocket 1 also functions as a rear cover that closes the opening at the other end (rear end) of housing main body 7 (described later).

[0015] The camshaft 2 is rotatably supported at the upper end of the cylinder head 01 via multiple cam brackets 02, and multiple egg-shaped cams (not shown) that open and close each of the intake valves and exhaust valves are fixed integrally to the outer periphery at predetermined axial positions.

[0016] As shown in FIG. 1, the camshaft 2 has a bolt insertion hole 2b formed inside one end 2a along the rotation axis. A female screw hole is formed in the bolt insertion hole 2b, into which a male screw portion 8c of a cam bolt 8, which will be described later, is screwed. The camshaft 2 has a first oil hole 2c on the retard side and a second oil hole 2d on the advance side formed in the radial direction of the rotation axis at one end 2a. The first oil hole 2c and the second oil hole 2d are arranged at a predetermined interval in the direction of the rotation axis of the camshaft 2. As shown in FIGS. 1 to 3, two first camshaft oil passages 18, 18 on the retard side and two second camshaft oil passages 19, 19 on the advance side are formed in parallel along the axial direction inside one end 2a of the camshaft 2.

[0017] As shown in Fig. 2, the two first camshaft oil passages 18, 18 are provided at symmetrical positions with the bolt insertion hole 2b as the central axis, with one end 18a, 18a opening into the first oil hole 2c, and the other end 18b, 18b opening into a pair of first axial oil holes 20, 20 on the retard side, which will be described later. As shown in Fig. 3, the two second camshaft oil passages 19, 19 are also provided at symmetrical positions with the bolt insertion hole 2b as the central axis, with one end 19a, 19a opening into the second oil hole 2d, and the other end 19b, 19b opening into a pair of second axial oil holes 21, 21 on the advance side, which will be described later. The first and second oil holes 2c, 2d and the first and second camshaft oil passages 18, 19 form a part of the hydraulic circuit 4.

[0018] As shown in Figures 1 to 3, the phase change mechanism 3 is connected to the sprocket 1 and comprises a housing 6 having an operating chamber therein, a vane rotor 9 accommodated within the housing 6 so as to be freely rotatable relative to one another and fixed to one end 2a of the camshaft 2 in the direction of the rotational axis via a cam bolt 8, and the operating chamber of the housing 6 is divided by the vane rotor 9 into multiple (four each in this embodiment) first hydraulic chambers, namely retard hydraulic chambers 15a, 15b, 15c, 15d, and second hydraulic chambers, namely advance hydraulic chambers 16a, 16b, 16c, 16d.

[0019] The housing 6 comprises a housing body 7 formed into a cylindrical shape from sintered metal like the sprocket 1, a front plate 10 formed by press molding that closes the front end opening of the housing body 7, and the sprocket 1 as a rear cover that closes the rear end opening.

[0020] The housing body 7 has a plurality of (four in this embodiment) first to fourth shoes 11a, 11b, 11c, and 11d integrally provided at approximately equal intervals in the circumferential direction on the inner circumferential surface thereof. Bolt insertion holes 12a to 12d are formed through the insides of the respective shoes 11a to 11d along the rotation axis direction of the housing body 7.

[0021] The first to fourth shoes 11a to 11d protrude from the inner circumferential surface of the housing body 7 in the direction of the rotation axis, and each is formed in a substantially trapezoidal shape when viewed from the side.

[0022] In addition, a lightening groove 7a is formed on the outer circumferential surface of the housing body 7 at a position corresponding to the first shoe 11a. This lightening groove 7a is used to reduce the weight of the housing body 7, improve the overall weight balance, and to position the housing body 7 relative to the sprocket 1 and the front plate 10.

[0023] The housing body 7 is provided on the outer surface of the first shoe 11a on the sprocket 1 side with a pin hole 7b into which a pin 1c used for positioning with the sprocket 1 is fitted.

[0024] As shown in FIG. 1, the cam bolt 8 is composed of a head 8a on the front plate 10 side, a shaft portion 8b extending from the head 8a to the camshaft 2 side, and a male screw portion 8c formed on the tip side of the shaft portion 8b and screwed into a female screw hole 2c of the camshaft 2. The head 8a of the cam bolt 8 has a flange portion 8d for seating integrally formed at the base of the shaft portion 8b. The shaft portion 8b of the cam bolt 8 is formed to have a relatively large outer diameter, and is formed to be larger than the shaft portion of the cam bolt in the prior art described in the above publication. The flange portion 8d is designed so that the seating surface on the shaft portion 8b side seats on the hole edge of a bolt insertion hole 13a of the vane rotor 9 described later when tightened.

[0025] The front plate 10 is formed into a disk shape by, for example, pressing an iron-based metal plate. The front plate 10 has a large-diameter insertion hole 10a formed through the center, and four bolt insertion holes (not shown) through which four bolts 5 are inserted are formed at approximately equally spaced positions in the circumferential direction on the outer periphery.

[0026] The housing body 7 , the front plate 10 and the sprocket 1 are fastened together by four bolts 5 .

[0027] The vane rotor 9 is formed as a single unit, for example by compressing and sintering metal powder, and as shown in Figures 1 to 3, has a rotor 13 directly fixed to one end 2a of the camshaft 2 by a cam bolt 8, and a plurality of (four in this embodiment) first to fourth vanes 14a to 14d that are integrally formed on the outer circumferential surface of the rotor 13 and extend radially at equal intervals of approximately 90° in the circumferential direction.

[0028] The rotor 13 has a bolt insertion hole 13a formed in the center in the direction of the rotation axis, through which the shaft portion 8b of the cam bolt 8 is inserted, and a circular fitting groove 13b is formed in the center of the rear end face on the sprocket 1 side into which the tip portion of one end 2a of the camshaft 2 is fitted. The rotor 13 also has a cylindrical portion 13c on the front end face on the front plate 10 side that is inserted into the insertion hole 10a and protrudes forward. As shown in FIG. 1, a spiral spring 36 is provided between the front plate 10 and the cylindrical portion 13c to bias the vane rotor 9 in the rotation direction on the advance side.

[0029] 2 and 3, the first to fourth vanes 14a to 14d are integrally provided on the outer periphery of the rotor 13 and are disposed between the respective shoes 11a to 11d. The respective vanes 14a to 14d divide the working chamber in the housing 6 into four first hydraulic chambers, i.e., retard hydraulic chambers 15a to 15d, and four second hydraulic chambers, i.e., advance hydraulic chambers 16a to 16d, depending on the relative relationship between the respective vanes 14a to 14d and the respective shoes 11a to 11d.

[0030] Among the four vanes 14a to 14d, the first vane 14a is formed wide in the circumferential direction, but the other three vanes 14b to 14d are formed thin and have almost the same circumferential width, thereby achieving a good weight balance of the entire vane rotor 9.

[0031] Further, seal members 17a that provide a seal while sliding against the inner circumferential surface of the housing body 7 are fitted and fixed into seal grooves formed in the outer surface of each of the tip ends of the vanes 14a to 14d. Meanwhile, seal members 17b that provide a seal while sliding against the outer circumferential surface of the rotor 13 are fitted and fixed into seal grooves formed in the inner circumferential surfaces of the tip ends of the shoes 11a to 11d.

[0032] As shown in Fig. 2, when the vane rotor 9 rotates counterclockwise, one side 14e of the first vane 14a comes into contact with the opposing side of the fourth shoe 11d, restricting the rotation position on the maximum retard side. As shown in Fig. 3, when the vane rotor 9 rotates clockwise, the other side 14f of the first vane 14a comes into contact with the opposing side of the first shoe 11a, restricting the rotation position on the maximum advance side. The first vane 14a and the two first and fourth shoes 11a and 11d function as mechanical stoppers that restrict the most retarded and most advanced positions of the vane rotor 9.

[0033] At this time, the other three second to fourth vanes 14b to 14d are separated from the opposing side surfaces of the shoes 11a to 11d that face each other in the circumferential direction, without abutting against them. Therefore, the accuracy of abutment between the first vane 14a and the first and fourth shoes 11a, 11d is improved, and the speed of supply of hydraulic pressure to the retard hydraulic chambers 15a to 15d and the advance hydraulic chambers 16a to 16d is increased, improving the forward and reverse rotation responsiveness of the vane rotor 9.

[0034] 1 to 3, the rotor 13 has two first axial oil holes 20, 20 on the retard side and second axial oil holes 21, 21 on the advance side formed linearly in the rotational axis direction of the rotor 13. The rotor 13 also has first radial oil passages 22, 22 formed therein that connect the first axial oil holes 20, 20 to the retard hydraulic chambers 15a to 15d, and second radial oil passages 23, 23 formed therein that connect the second axial oil holes 21, 21 to the advance hydraulic chambers 16a to 16d.

[0035] The two first axial oil holes 20, 20 are provided at symmetrical positions about the bolt insertion hole 13a of the cam bolt 8, with one end of each communicating with the other end 18b of the first camshaft oil passage 18 and the other end communicating with each of the first radial oil passages 22, 22. The two second axial oil holes 21, 21 are similarly provided at symmetrical positions about the bolt insertion hole 13a, with one end of each communicating with the other end 19b of the second camshaft oil passage 19 and the other end communicating with each of the second radial oil passages 23, 23.

[0036] 2 and 3, each of the first radial oil passages 22, 22 and each of the second radial oil passages 23, 23 is bent in an L-shape, and the outer ends of the long passages 22a, 22a and the short passages 22b, 22b of the first radial oil passages 22, 22 communicate with the four retard hydraulic chambers 15a to 15d, and the vicinity of the junction of the long passages 22a, 22a and the short passages 22b, 22b communicate with the first axial oil holes 20, 20. The outer ends of the long passages 23a, 23a and the short passages 23b, 23b of the second radial oil passages 23, 23 also communicate with the four advance hydraulic chambers 16a to 16d, and the vicinity of the junction of the long passages 23a, 23a and the short passages 23b, 23b communicate with the second axial oil holes 21, 21.

[0037] Fig. 4 is a cross-sectional view of a main part showing the relationship between the second camshaft oil passage, the second axial oil hole, and the second radial oil passage in this embodiment, and Fig. 5 is a schematic diagram showing the connection state between the second camshaft oil passage, the second axial oil hole, and the second radial oil passage on the advance side in this embodiment. Although Fig. 4 and Fig. 5 show the relationship between the second camshaft oil passage, the second axial oil hole, and the second radial oil passage, the relationship between the first camshaft oil passage, the first axial oil hole, and the first radial oil passage is also the same, so for the purpose of explanation, they will also be described as the relationship between the first camshaft oil passage, the first axial oil hole, and the first radial oil passage. As shown in Figures 1, 4 and 5, the first and second axial oil holes 20-21 have the same inner diameter d and are uniformly formed along the axial direction. The inner diameter d of each of the first and second axial oil holes 20-21 is larger than the inner diameter d1 of each of the first and second camshaft oil passages 18-19 and is also larger than the inner diameter d2 of each of the first and second radial oil passages 22-23. The inner diameter d2 of each of the first and second radial oil passages 22-23 is also larger than the inner diameter d1 of each of the first and second camshaft oil passages 18-19.

[0038] As shown in FIG. 4, the axial positions P of the first and second axial oil holes 20-21 are offset radially outward from the rotor 13 relative to the axial positions P1 of the first and second camshaft oil passages 18-19, and the portions 21a, 21a of the inner surfaces of the first and second axial oil holes 20-21 on the bolt insertion hole 13a side are substantially overlapped (inscribed) with the corresponding portions of the inner surfaces of the camshaft oil passages 18-19.

[0039] The first and second radial oil passages 22-23 are disposed such that the axial center positions P2 of the long passages 22a,23a are offset slightly radially outward from the axial center positions P of the first and second axial oil holes 21,21.

[0040] As shown in Figures 1 to 3, the hydraulic circuit 4 selectively supplies or discharges hydraulic oil (hydraulic pressure) to each of the retard and advance hydraulic chambers 15a to 15d, 16a to 16d via first radial oil passages 22, 22 and second radial oil passages 23, 23.

[0041] That is, the hydraulic circuit 4 has the above-mentioned first and second radial oil passages 22-23, first and second axial oil holes 21-22, first and second camshaft oil passages 18-19, and a retard oil passage 25 and an advance oil passage 26 which communicate with the first and second camshaft oil passages 18-19 via the first and second oil holes 2c, 2d. The hydraulic circuit 4 also has an oil pump 27 which is a fluid pressure supply source that selectively supplies hydraulic oil to the retard and advance oil passages 25, 26, and an electromagnetic switching valve 28 which switches the supply and discharge flow paths for the retard oil passage 25 and the advance oil passage 26 depending on the operating state of the engine.

[0042] The oil pump 27 is a typical type such as a trochoid pump that is rotationally driven by the crankshaft of the engine. The oil pump 27 draws in lubricating oil from a suction passage 27b and supplies it from a discharge passage 27b to a main oil gallery (M / G) and an electromagnetic switching valve 28 via a filter 29. A relief valve 30 is provided downstream of the discharge passage 27b to prevent the discharge pressure from becoming excessively high.

[0043] The solenoid switching valve 28 is a three-port, two-position proportional valve, and the other end of the retard oil passage 25 and the advance oil passage 26 are connected to two supply and discharge ports formed in a valve body (not shown). The solenoid switching valve 28 moves a spool valve body, which is slidably provided in the axial direction in the valve body, in the front-rear direction by a control current (pulse current) output from a control unit (not shown). This causes the discharge passage 27b of the oil pump 27 to communicate with either the retard oil passage 25 or the advance oil passage 26. At the same time, the drain passage 31 communicates with the other of the retard oil passage 25 or the advance oil passage 26.

[0044] The control unit detects the current engine operating state by inputting information signals from various sensors, such as a crank angle sensor (not shown) (for detecting engine speed), an air flow meter, an engine water temperature sensor, an engine temperature sensor, a throttle valve opening sensor, and a cam angle sensor that detects the current rotation phase of the camshaft 2, through which an internal computer outputs a control current to each coil of the electromagnetic switching valve 28 to control the moving position of the spool valve body and thereby control the switching of each of the oil passages 25, 26.

[0045] As shown in FIG. 2, a lock mechanism 32 is provided that locks the vane rotor 9 relative to the housing 6 at a rotational position on the most retarded angle side (the position in FIG. 2).

[0046] This locking mechanism 32 is mainly composed of a lock hole formed by a lock hole component (not shown) fixed into a fixing hole provided on the inner circumference of the inner surface of the sprocket 1, a pin accommodating hole 33 provided in the internal axial direction of the first vane 14a, a lock pin 34 slidably provided in the pin accommodating hole 33 and inserted into or removed from the lock hole, a release passage (not shown) that moves the lock pin 34 out of the lock hole 32 to release the lock, and a coil spring that urges the lock pin 34 toward the lock hole 32.

[0047] The lock hole in the inner surface of the sprocket 1 is disposed on the fourth shoe 11d side, which is the retarded angle side. The pin accommodating hole 33 is formed inside the first vane 14a and extends along the rotational axis of the rotor 13.

[0048] The release passage is formed on one side of the first vane 14a, and applies hydraulic pressure to the lock pin 34 from one of the retard hydraulic chambers 15a or advance hydraulic chambers 16d against the spring force of the coil spring to move the lock pin 34 backward. In other words, the lock pin 34 receives the operating hydraulic pressure supplied to the retard hydraulic chamber 15a or advance hydraulic chamber 16d from the release passage, and comes out of the lock hole to release the lock on the vane rotor 9. [Action of this embodiment] The operation of the valve timing control device according to this embodiment will now be described.

[0049] When the ignition switch is turned off, the output of the control current from the control unit to the solenoid controlled directional control valve 28 is stopped, and the drive of the oil pump 27 is stopped. As a result, the spool valve of the solenoid controlled directional control valve 28 is held in its original position by the spring force, and the supply of hydraulic pressure to each of the retard hydraulic chambers 15a-15d and each of the advance hydraulic chambers 16a-16d is stopped. Then, until the engine is completely stopped, the vane rotor 9 rotates relative to the housing 6 toward the most advanced side due to the alternating torque (negative torque) acting on the camshaft 2 and the torque of the spiral spring 36.

[0050] On the other hand, since the supply of hydraulic pressure to the retard hydraulic chamber 15a is stopped, the lock pin 34 is not subjected to hydraulic pressure in the backward direction, and the spring force of the coil spring causes the tip of the lock pin 34 to be inserted into the lock hole at the most advanced position. Therefore, as shown in FIG 3, one side surface 14f of the first vane 14a abuts against the opposing side surface of the first shoe 11a, and the vane rotor 9 is restricted to the relative rotation position on the most advanced side.

[0051] Thereafter, when the ignition switch is turned on to restart the engine, the exhaust valve opening and closing timing during cranking is set to the most advanced side, which results in stable starting and improved startability.

[0052] Thereafter, when the operating state of the engine changes, the control current output from the control unit causes the spool valve of the electromagnetic switching valve 28 to communicate between the discharge passage 27b and the advance oil passage 26, and also between the retard oil passage 25 and the drain passage 31.

[0053] Therefore, the hydraulic oil (hydraulic pressure) discharged from the oil pump 27 is supplied from the advance oil passage 26 through the second oil hole 2d, each of the second camshaft oil passages 19, each of the second axial oil holes 21, and each of the second radial oil passages 23 into each of the advance hydraulic chambers 16a to 16d. Furthermore, the hydraulic oil (hydraulic pressure) that flows into one of the advance hydraulic chambers 16d flows into the pressure receiving portion of the lock pin 34 through the release passage and acts in a direction to move the lock pin 34 backward. Therefore, the lock pin 34 backwards against the spring force of the spring, and the tip portion comes out of the lock hole, releasing the lock of the vane rotor 9 to the housing 6. This ensures free rotation of the vane rotor 9.

[0054] Meanwhile, the hydraulic oil in each retard hydraulic chamber 15a-15d flows from each first radial oil passage 22 to the first axial oil hole 20 and the first camshaft oil passage 18 into the retard oil passage 25, passes through the electromagnetic switching valve 28, and is discharged into the oil pan 35 through the drain passage 31.

[0055] Therefore, the retard hydraulic chambers 15a-15d are at low pressure, while the advance hydraulic chambers 16a-16d are at high pressure. As a result, the vane rotor 9 is maintained in a relative rotation position in the clockwise direction (advance side) as shown in Fig. 3, with one side surface 14f of the first vane 14a abutting against the opposing side surface of the first shoe 11a, and is restricted and held in the most advance rotation position.

[0056] This eliminates valve overlap between the intake valve and the exhaust valve, suppressing the backflow of combustion gases, resulting in good combustion conditions, improved fuel economy, and stabilized engine revolutions.

[0057] When the operating condition of the engine changes further, the control current output from the control unit causes the spool valve of the electromagnetic switching valve 28 to communicate between the discharge passage 27b and the advance oil passage 26 and also between the retard oil passage 25 and the drain passage 31.

[0058] Therefore, the hydraulic oil discharged from the discharge passage 27b of the oil pump 27 to the retard oil passage 25 flows from the first oil hole 2c into the first camshaft oil passage 18, and from there flows into the first axial oil hole 20 and the first radial oil passage 22, and is quickly supplied to each of the retard hydraulic chambers 15a to 15d.

[0059] In addition, the hydraulic oil in each advance hydraulic chamber 16a to 16d passes through each second radial oil passage 23, each second axial oil hole 21, the second camshaft oil passage 19, the second oil hole 2d, the advance oil passage 26, the electromagnetic switching valve 28, and is discharged from the drain passage 31 into the oil pan 35.

[0060] Therefore, the advance hydraulic chambers 16a-16d are at low pressure, while the retard hydraulic chambers 15a-15d are at high pressure. As a result, the vane rotor 9 rotates counterclockwise (toward the retard side) as shown in Fig. 2, and the other side 14e of the first vane 14a comes into contact with the opposing side of the first shoe 11d, and is restricted and held at the rotation position on the most retard side. This increases the valve overlap between the intake valve and the exhaust valve, thereby enabling the engine to produce higher power.

[0061] In this embodiment, the inner diameter d of the first and second axial oil holes 20, 21 is formed larger than the inner diameter d1 of the corresponding first and second camshaft oil passages 18, 19, and the opening ends of the other ends 18b, 19b of the camshaft oil passages 18, 19 are arranged within the opening range of the opposing opening ends of the axial oil holes 20, 21. This prevents the opening ends of the other ends 18b, 19b of the camshaft oil passages 18, 19 from shifting radially to the opening ends of the axial oil holes 20, 21, and ensures a proper communication state at all times. As a result, the generation of flow resistance of the oil flowing from the camshaft oil passages 18, 19 toward the axial oil holes 20, 21 is particularly suppressed, ensuring a smooth flow.

[0062] Moreover, by offsetting the first and second axial oil holes 20, 21 radially outward from the rotor 13 by a predetermined amount α, it is possible to ensure a large distance between each of the axial oil holes 20, 21 and the first and second radial oil passages 22, 23 with respect to the inner circumferential surface of the bolt insertion hole 13a formed through the center of the rotor 13. In other words, by offsetting the first and second axial oil holes 20, 21 radially outward, it is possible to provide a sufficient distance L, L1 between each of the axial oil holes 20, 21 and the first and second radial oil passages 22, 23 with respect to the bolt insertion hole 13a.

[0063] This allows the thickness between each of the axial oil holes 20, 21 and each of the radial oil passages 22, 23 and the bolt insertion hole 13a to be increased. This makes it possible to suppress a decrease in the rigidity of the rotor 13, and also makes it possible to increase the sealing area between the bolt insertion hole 13a and each of the axial oil holes 20, 21 and each of the radial oil passages 22, 23, improving the sealing performance between them. As a result, it is possible to suppress the oil in each of the axial oil holes 20, 21 and each of the radial oil passages 22, 23 from leaking into the bolt insertion hole 13a.

[0064] In addition, by offsetting the axial oil holes 20, 21 radially outward from the rotor 13, the degree of freedom in the layout of the radial oil passages 22, 23 is increased. That is, as described above, by separating the axial oil holes 20, 21 from the bolt insertion hole 13a, the degree of freedom in the layout, such as the formation angle of the radial oil passages 22, 23, is improved. This increases the versatility for use with various valve timing control devices.

[0065] FIG. 6 is a schematic view showing, in a see-through manner, the flow characteristics of the oil that has flowed from the second camshaft oil passage shown in FIG. 5 into the second axial oil hole and the second radial oil passage.

[0066] As described above, by offsetting the axial position P of each of the axial oil holes 20, 21 by a predetermined amount α from the axial position P1 of each of the camshaft oil passages 18, 19, as shown in FIG. 6, a swirling flow is easily generated in the oil (in multiple linear shapes) that flows from each of the camshaft oil passages 18, 19 through each of the axial oil holes 20, 21 into each of the radial oil passages 22, 23.

[0067] That is, according to an experiment conducted by the inventor of the present application, when the pressure of the oil O flowing into each of the camshaft oil passages 18, 19 is 400 kPa and the flow rate is 13 L / min, a spiral swirling flow is generated inside due to the offset arrangement of each of the axial oil holes 20, 21, and the oil O that has become the swirling flow flows into each of the radial oil passages 22, 23. In the long passages 22a, 23a of each of the radial oil passages 22, 23, the pressure of the oil O becomes 323 kPa and the flow rate becomes 7.6 L / min due to the flow resistance caused by the swirling flow, and in the short passages 22b, 23b, the pressure becomes 357 kPa and the flow rate becomes 5.4 L / min due to the flow resistance caused by the swirling flow. Therefore, the pressure difference between the long paths 22a, 23a and the short paths 22b, 23b is 34 kPa and the flow rate difference is 2.2 L / min, so that the pressure difference and flow rate difference are almost equal without any large difference.

[0068] Therefore, the amount of oil per unit time to the four retard hydraulic chambers 15a-15d and the four advance hydraulic chambers 16a-16d can be supplied in a well-balanced manner from each of the radial oil passages 22, 23. As a result, an almost equal amount of oil pressure acts on each of the vanes 14a-14d, improving the operational response of the relative conversion angle between the housing 6 and the vane rotor 9.

[0069] In addition, as described above, since hydraulic pressure can be quickly supplied to the retard hydraulic chamber 15a and the advance hydraulic chamber 16d, the speed at which the unlocking hydraulic pressure acting on the lock pin 34 of the lock mechanism 32 is supplied is increased. This increases the speed at which the lock pin 34 is unlocked. This increases the speed at which the conversion angle of the vane rotor 9 can be switched in response to changes in the engine operation. In this embodiment, the first and second camshaft oil passages, the first and second axial oil holes, and the first and second radial oil passages on both the retard side and the advance side are described. However, it is also possible to have only the first oil passage on the retard side, or only the second oil passage on the advance side, for example. [Explanation of symbols]

[0070] 1...timing sprocket, 2...camshaft, 2a...one end, 2c, 2d...first and second oil holes, 3...phase change mechanism, 4...hydraulic circuit, 6...housing, 8...cam bolt, 8a...head, 8b...shaft, 8c...male thread, 9...vane rotor, 10...front plate, 11a-11d...shoe, 15a-15d...retard hydraulic chamber, 16a-16d...advance hydraulic chamber, 13...rotor, 13a...bolt insertion hole, 14a-14d...vane, 15a-15d...retard hydraulic chamber (first hydraulic chamber), 16 a to 16d... advance hydraulic chamber (second hydraulic chamber), 18... first camshaft oil passage, 18a... one end, 18b... other end, 19... second camshaft oil passage, 19a... one end, 19b... other end, 20... first axial oil hole, 21... second axial oil hole, 22... first radial oil passage, 22a... long passage (one end), 22b... short passage (other end), 23... second radial oil passage, 23a... long passage (one end), 23b... short passage (other end), 25... retard oil passage, 26... advance oil passage, 27 oil pump, 28... solenoid switching valve.

Claims

1. a housing to which a rotational force from a crankshaft is transmitted and which has an operating chamber therein; A vane rotor disposed inside the housing so as to be capable of relative rotation, A rotor fixed to the camshaft by a cam bolt; a plurality of vanes provided on the rotor and dividing the working chamber into a plurality of first hydraulic chambers and a plurality of second hydraulic chambers; a plurality of axial oil holes formed inside the rotor along a direction of a rotation axis of the rotor, the plurality of axial oil holes communicating with a plurality of camshaft oil passages formed in the camshaft, the plurality of axial oil holes having inner diameters larger than inner diameters of the camshaft oil passages and having axial center positions offset radially outward with respect to the camshaft oil passages; a vane rotor having a first radial oil passage, the first radial oil passage communicating with each of the axial oil holes, the first radial oil passage having a linear end opening into one of the first hydraulic chambers and a bent other end opening into the other of the first hydraulic chambers; A valve timing control device for an internal combustion engine comprising:

2. 2. A valve timing control device for an internal combustion engine according to claim 1, an inner diameter of each of the axial oil holes is larger than an inner diameter of each of the first radial oil passages, and an axial center position of each of the first radial oil passages is offset radially outward from the rotor with respect to an axial center of each of the axial oil holes.

3. 3. A valve timing control device for an internal combustion engine according to claim 2, a circular end of the axial oil hole and a circular end of the camshaft oil passage that opens into the axial oil hole are arranged such that their hole edges are inscribed on the radial inside of the rotor.

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