JP2008051115A - Cam phase varying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cam phase varying device for preventing various troubles due to unbalance by striking a precise rotation balance. <P>SOLUTION: Weight adjusting parts 41, 42 are provided on one side of bodies 4, 7, 8 for striking a rotation balance at the turning position of a phase varying member 12 during idling operation in the assembled state of the bodies 4, 7, 8 with the phase varying member 12. Namely, the cam phase varying device strikes the rotation balance in the assembled state same as that in actual operation and in the idling operated state in which an driver may be sensitive to noises or vibration resulting from unbalance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cam phase variable device that adjusts the opening / closing timing of an intake valve and an exhaust valve of an internal combustion engine (hereinafter referred to as an engine) according to an operating state.

As this type of conventional cam phase varying device, for example, the one disclosed in Patent Document 1 can be cited. This variable device is provided on a cam sprocket that is rotationally driven by a crankshaft, and a vane rotor connected to the camshaft is disposed inside, and the phase of the vane rotor is changed to an advance side or a retard side by hydraulic pressure, The camshaft phase with respect to the cam sprocket is changed, and as a result, the opening and closing timing of the intake and exhaust valves is adjusted.
Japanese Patent Laid-Open No. 9-60508

  As is well known, since the camshaft rotates at a high speed at half the engine rotation speed, a precise rotation balance is required for the cam phase variable device that rotates with the camshaft. However, the cam phase varying device described in the above publication does not give consideration to the rotational balance, and various problems due to unbalance, for example, increased friction when an unbalanced load is applied to the bearing portion as the camshaft rotates. There is a possibility that vibration and noise may be generated due to engine seizure due to seizure or seizure, or camshaft rotation fluctuation.

  An object of the present invention is to provide a cam phase varying device that can precisely balance the rotational balance and prevent various problems due to unbalance.

  In order to achieve the above object, according to the first aspect of the present invention, a main body that is rotationally driven by a crankshaft of an internal combustion engine, and a camshaft that is disposed in the main body so as to be relatively rotatable and is connected to a valve shaft driving camshaft. A phase variable member whose rotational position in the main body is adjusted according to the rotational speed of the internal combustion engine, and a phase variable member provided on one side of the main body and set when the internal combustion engine is in idle operation. And a weight adjusting unit that balances the rotational balance in the assembly state of the main body and the phase variable member at the moving position.

  Since the ambient noise (engine combustion noise and running noise) and vibration are low when the vehicle is stopped during idle operation, if the camshaft changes due to imbalance of the cam phase variable device, the engine malfunctions. There is a tendency for drivers to feel noise and vibration sensitively. In the present invention, the balance of rotation is balanced in the operating state during idling where the driver tends to be sensitive to noise and vibration, and the balance of rotation is balanced in the same assembly state as in actual operation. It is done.

According to a second aspect of the present invention, in the first aspect of the invention, a rotation restricting member for restricting the rotation of the phase variable member at the rotation position of the idle operation when the internal combustion engine is stopped is provided.
Therefore, the balancing operation of the main body and the phase variable member by the weight adjusting unit is performed in a state where the phase variable member is held at the rotation position of the idle operation by the rotation restriction member.
According to a third aspect of the present invention, in the first or second aspect, the phase variable member is located at the most retarded angle position on one end side of the rotation stroke or the most advanced angle position on the other end side of the rotation stroke in the idling operation of the internal combustion engine. The weight adjustment unit is adjusted to balance the rotational balance at the most retarded angle position or the most advanced angle position of the phase variable member.

  Therefore, in idling operation of the internal combustion engine, the phase variable member is adjusted to the most retarded position or the most advanced position, and the rotation balance is balanced by the weight adjusting unit at this rotational position.

  As described above, according to the cam phase varying device of the first to third aspects of the present invention, the rotational balance is precisely balanced during idle operation where the driver tends to be sensitive to noise and vibration caused by unbalance. As a result, it is possible to prevent a situation in which the driver feels uncomfortable due to noise or vibration when the engine malfunctions due to the fluctuation of the rotation of the camshaft.

Hereinafter, an embodiment in which the present invention is embodied in a cam phase varying device that adjusts the opening / closing timing of an intake valve will be described.
As shown in FIGS. 1 and 2, a camshaft 3 on the intake side is supported on a bearing portion 2 of a cylinder head 1 of an engine so as to be rotatable and immovable in an axial direction. The intake valve (not shown) is driven to open and close. The front end of the camshaft 3 protrudes laterally from the cylinder head 1 and a boss 4a of the timing pulley 4 is rotatably fitted. The timing pulley 4 is connected to a crankshaft (not shown) via a timing belt 5, The camshaft 3 is rotationally driven by being reduced in half in the direction of the arrow in FIG. 2 around the axis of the camshaft 3. Although not shown, an exhaust side timing pulley is also connected to the timing belt 5 so that the exhaust valve is driven to open and close by an exhaust side camshaft. An oil seal 6 is fitted between the boss portion 4a of the timing pulley 4 and the bearing portion 2 to prevent the oil from flowing out from the cylinder head 1 to the outside.

  A housing 7 and a front cover 8 are fixed by bolts 9 on one side of the timing pulley 4, and a substantially cross-shaped hydraulic chamber 10 centering on the axis of the camshaft 3 is formed inside the housing 7 and a front cover 8. The oil tightness is maintained. A vane rotor 12 is disposed in the hydraulic chamber 10, and a central portion thereof is positioned at a front end of the camshaft 3 by a knock pin (not shown) and fixed by a cam bolt 14. A head 14 a of the cam bolt 14 is located in an oil distribution chamber 15 formed in the vane rotor 12, and the distribution chamber 15 is closed by a plug 16 screwed into the front cover 8. In this embodiment, the timing pulley 4, the housing 7, and the front cover 8 function as a main body, and the vane rotor 12 functions as a phase variable member.

  The vane rotor 12 has a substantially cross shape corresponding to the hydraulic chamber 10, and an arcuate movable sliding contact surface 12 b that comes into contact with the fixed sliding contact surface 10 a of the hydraulic chamber 10 is formed between the four vanes 12 a at intervals of 90 degrees. An oil seal 18 is provided at the tip of each vane 12a. These sliding contact surfaces 10a and 12b divide the hydraulic chamber 10 into four corresponding to each vane 12a. Within each hydraulic chamber 10, there are a retard hydraulic chamber 17a and an advanced hydraulic chamber 17b on both sides of the vane 12a. Is formed.

  As shown by the solid line in FIG. 2, the vane rotor 12 has the most retarded angle position at which the volume of the retarded hydraulic chamber 17a is maximized by bringing the advanced hydraulic chamber 17b side of each vane 12a into contact with the inner wall of the hydraulic chamber 10. And the most advanced angle position at which the retarded hydraulic chamber 17a side of each vane 12a is brought into contact with the other inner wall of the hydraulic chamber 10 to maximize the volume of the advanced hydraulic chamber 17b. The camshaft 3 can rotate around the axis of the camshaft 3. As a result, the phase of the camshaft 3 with respect to the timing pulley 4 changes, and the opening / closing timing of the intake valve is changed.

  As shown in FIGS. 2 and 3, each vane 12 a of the vane rotor 12 has a pin hole 19 penetrating in the thickness direction (the axial direction of the camshaft 3), and a lock pin 20 ( A rotation restricting member) is slidably fitted in the axial direction. The length of the lock pin 20 is set substantially equal to the thickness of the vane rotor 12, and the tip of the lock pin 20 (the lower end in FIG. 3) is chamfered in a tapered shape. The timing pulley 4 is formed with a lock hole 21 corresponding to each pin hole 19 when the vane rotor 12 is at the most retarded position, and each lock hole 21 is a tapered cross-sectional shape corresponding to the tip of the lock pin 20. I am doing. The lock pin 20 slides in the pin hole 19, and as shown in FIG. 3, the front end is fitted into the lock hole 21 to lock the vane rotor 12 at the most retarded position, and the front end is the lock hole. It is switched between a lock release position that allows the vane rotor 12 to rotate by being separated from the inside 21.

  The vane rotor 12 is formed with a lock oil passage 22a that communicates the inside of the pin hole 19 and the retard hydraulic chamber 17a, and an unlock oil passage 22b that communicates the inside of the pin hole 19 and the advance hydraulic chamber 17b. As will be described later, when the hydraulic pressure in the retard hydraulic chamber 17a increases, the hydraulic pressure acts on the proximal end side of the lock pin 21 via the lock oil passage 22a to switch to the lock position, and in the advance hydraulic chamber 17b. When the hydraulic pressure increases, the hydraulic pressure acts on the distal end side of the lock pin 21 via the lock release oil passage 22b and switches to the lock release position.

  On the other hand, four advance angle introduction oil passages 23 are formed radially in the vane rotor 12 around the oil distribution chamber 15, one end of each advance angle introduction oil passage 23 opens into the oil distribution chamber 15, and the other end is Each is open in the advance hydraulic chamber 17b. The oil distribution chamber 15 is an oil groove formed on the entire outer periphery of the camshaft 3 through a through oil passage 24 that penetrates the cam bolt 14, a first oil passage 25 that continues from the through oil passage 24, and a second oil passage 26. 27, and is always in communication with the advance angle supply oil passage 28 formed in the bearing portion 2 regardless of the rotation angle of the camshaft 3.

  On the other hand, four retard angle introducing oil passages 29 are formed in the vane rotor 12 radially, and one end of each retard angle introducing oil passage 29 opens into the retard angle hydraulic chamber 17a. The other end of each retarded-introducing oil passage 29 opens into the oil groove 32 of the camshaft 3 via the third oil passage 30 and the fourth oil passage 31, respectively, and the retarded-feed oil passage formed in the bearing portion 2 33 is always in communication with the camshaft 3 regardless of the rotation angle of the camshaft 3.

  As shown in FIG. 1, the advance oil supply passage 28 and the retard supply oil passage 33 are discharged into the oil tank 34 and the pressure supply passage 36 through which the hydraulic oil in the oil tank 34 is pumped by the oil pump 35. The discharge passage 37 is connected via the switching valve 38, and the supply oil passages 28 and 33 are alternately communicated with the pressure feed passage 36 and the discharge passage 37 or both are shut off according to the switching operation of the switching valve 38. .

  As shown in FIG. 1, a front side balance hole 41 is formed on one side of the front side of the front cover 8, and a back side balance hole 42 is formed on one side of the rear side of the timing pulley 4. These balance holes 41, 42 are drilled with a drill in order to balance the rotational balance of the cam phase varying device. In the figure, for the sake of easy understanding, an example in which the balance holes 41 and 42 are provided one by one at the same phase position is shown, but in actuality, on a predetermined radius centered on the axis of the camshaft 3. The necessary number of balance holes 41 and 42 are provided at the phase positions where the rotational balance is balanced. In this embodiment, these balance holes 41 and 42 function as a weight adjusting unit.

Next, the procedure of the balancing operation will be described.
The rotation balance is balanced by the assembly of the cam phase variable device on the rotating jig simulating the camshaft 3 (except for the hydraulic circuit such as the switching valve 38, the timing pulley 4, the housing 7 and the front cover rotating together with the camshaft 3). 8) is assembled and confirmed. First, when the manufacture of each component constituting the cam phase varying device is completed, each component is sequentially assembled to the rotating jig in the same manner as in the actual assembly state on the camshaft 3 to complete the assembly. .

  Next, the balancing operation is performed. As is apparent from the configuration of FIG. 2, the rotational center of gravity of the cam phase varying device moves in accordance with the phase position of the internal vane rotor 12, so that it rotates at all phase positions. It is impossible to balance. Therefore, it is necessary to balance the rotational balance by focusing on a specific phase position of the vane rotor 12, and in this embodiment, balancing is performed at the most retarded angle position.

  Specifically, first, the cam phase varying device is gripped and rotated relative to the rotating jig, and the vane rotor 12 is switched to the most retarded position in FIG. Next, in order to maintain this most retarded angle position, the lock pin 20 is switched to the lock position. However, in the assembled state, the lock pin 20 cannot be touched and directly operated. Therefore, utilizing the fact that the lock pin 20 is made of an iron-based material, as shown in FIG. 3, the lock pin 20 is attracted by the magnet M from the back side of the timing pulley 4 and switched to the lock position.

  In this state, the cam phase variable device is rotated and driven together with the rotating jig to check the balanced state of the rotation balance, and the balance holes 41 and 42 are appropriately drilled at the phase positions where the center of gravity is biased on both the front side and the back side. Perforate. Although not described in detail, this balancing operation procedure uses a general balancing method. Note that the same effect can be obtained by fixing the weight on the opposite side of the phase position where the center of gravity is biased instead of the perforation of the balance holes 41 and 42.

  With the above balancing operation, the cam phase varying device is in the same assembly state as that during actual operation assembled to the engine, and the rotational balance is most balanced in a state where the vane rotor 12 is held at the most retarded position. Become. Thereafter, the cam phase varying device is removed from the rotating jig and assembled to the engine as it is without disassembling. Therefore, there is no possibility that the rotational balance is deteriorated due to the positional relationship between the components being reassembled, and the cam phase varying device is assembled to the engine in the best condition at the time of balancing. Further, since the balance holes 41 and 42 are drilled in the assembled state in this way, it is possible to avoid a malfunction when the chips adhere to the inside of the hydraulic chamber 10 or the like.

Next, the operation status of the cam phase varying device of this embodiment will be described.
First, when the engine is stopped, the vane rotor 12 is switched to the most retarded position shown by the solid line in FIG. 2 (advance amount 0 ° in FIG. 4) and rotated by the lock pin 20 switched to the lock position shown in FIG. It is regulated. When the engine is started, the switching valve 38 is switched to the position shown in FIG. 1, and the hydraulic oil from the oil pump 35 passes through the retard supply oil passage 33, the fourth oil passage 31, the third oil passage 30, and the retard introduction oil passage 29. Then, the vane rotor 12 is introduced into the retarded hydraulic chamber 17a to hold the vane rotor 12 at the most retarded position. The purpose of holding the vane rotor 12 at the most retarded angle position at the time of starting in this way is for the purpose of improving startability, and the lock pin 20 is operated by the oil pump 35 upon completion of starting and the retarded hydraulic chamber 17a. It plays a role of holding the vane rotor 12 in the most retarded position until the internal hydraulic pressure is raised.

  The rotational position of the vane rotor 12 after the start is completed is controlled based on the engine rotational speed Ne and the engine torque Tq (load) according to the map of FIG. As is apparent from the figure, the higher the engine speed Ne or the lower the engine torque, the smaller the advance amount is applied to control the vane rotor 12 to the retard side. The purpose of this control characteristic is to improve the charging efficiency of intake air by reducing the overlap with the exhaust side by controlling to the retard side.

  For example, when the vehicle is started after the start is completed, a progressively larger advance amount is set as the engine rotational speed Ne and the engine torque Tq increase. Accordingly, the switching valve 38 is switched to a position opposite to that shown in FIG. 1, and the working oil is supplied to the advance angle supply oil passage 28, the second oil passage 26, the first oil passage 25, the through oil passage 24, the oil distribution chamber 15, and the advance. The oil is introduced into the advance hydraulic chamber 17b through the corner introduction oil passage 23. The lock pin 20 is switched to the unlocking position by the hydraulic pressure, and the vane rotor 12 is rotated to the advance side, and when the predetermined position is reached, the switching valve 38 is switched to the neutral position to maintain the rotating position of the vane rotor 12. To do.

  Here, as the engine operating situation when the vane rotor 12 is controlled to the most retarded angle position, in addition to the above-described engine start, a high rotation range and a low torque range are exemplified as is apparent from the map of FIG. Can do. As described above, the cam phase varying device has the most balanced rotational balance at the most retarded angle position, and therefore can avoid problems due to unbalance described below.

  First, in the high rotation range, if the cam phase variable device is unbalanced, an unbalanced load is applied to the bearing portion 2 as the cam shaft 3 rotates, but the rotation balance of the cam phase variable device is balanced. Therefore, an uneven load is prevented, and an increase in friction and seizure of the bearing portion 2 caused thereby can be avoided in advance. Furthermore, since an uneven load acting on the timing belt 5 is also prevented, its durability can be improved.

The rotation balance is most balanced in the rotation range of 6000 to 7000 rpm corresponding to the most retarded angle position, but the region where the vane rotor 12 does not change so much from the most retarded angle position, for example, 5000 corresponding to an advance angle of about 10 °. Since a sufficiently good rotation balance can be obtained even in the rotation range of 6000 rpm, the above-described problems can be avoided.
In the low torque range, the driver is most sensitive to noise and vibration because the surrounding noise (engine combustion noise and running noise) and vibration are low, such as during idling. Since the rotational balance of the cam phase varying device is balanced, the rotational fluctuation of the camshaft 3 is prevented, and vibrations and noises caused by engine malfunction caused thereby can be avoided, and a very good driving environment can be provided to the driver. .

  This is the end of the description of the embodiment. However, the embodiment of the present invention is not limited to this embodiment. For example, in the above embodiment, the cam phase varying device is attached to the intake camshaft 3 and the phase thereof is adjusted. In addition, a similar cam phase varying device may be attached to the exhaust camshaft. In this case, according to the map shown in FIG. 5, for example, according to the map shown in FIG. 5, the higher the engine rotation speed Ne or the higher the engine torque, the larger the advance amount is applied to the vane rotor 12 toward the advance side. Control and improve the charging efficiency of intake air by reducing the overlap with the intake side. In addition, the idling side is also controlled during idling to reduce the overlap and to stabilize the rotation by reducing EGR. On the exhaust side, the vane rotor 12 needs to be held at the most advanced angle position in order to improve startability. Therefore, the position of the lock hole 21 is changed so that the rotation of the vane rotor 12 can be restricted at the most advanced angle position.

  The cam phase varying device used on the exhaust side performs the balancing operation in the same procedure as that on the intake side while the lock pin 20 holds the most advanced position. In other words, as described above, the rotational balance is controlled to the most advanced angle position in the high rotational range where the balance of the rotational balance is most required and during idling. Therefore, the rotational balance is most balanced at the most advanced angle position. As a result, as described in the cam phase variable device on the intake side, problems due to imbalance, that is, increased friction and seizure of the bearing portion 2 in the high rotation range, and vibration and noise generation due to engine malfunction during idling can be avoided. can do.

  In the above embodiment, the hydraulic cam phase variable device that rotates the vane rotor 12 using the hydraulic pressure from the oil pump 35 is embodied. However, the operation principle is not limited to this, for example, Further, the present invention may be embodied in a cam phase variable device using an electric motor or the like as a drive source.

It is the II sectional view taken on the line of FIG. 2 which shows the cam phase variable apparatus of an Example. It is a cross-sectional view showing the cam phase varying device at the most retarded angle position. It is the III-III sectional view taken on the line of FIG. It is explanatory drawing of the map which shows the advance angle characteristic by the side of intake. It is explanatory drawing of the map which shows the advance angle characteristic by the side of exhaust.

Explanation of symbols

3 Camshaft 4 Timing pulley (Main body)
7 Housing (main body)
8 Front cover (main unit)
12 Vane rotor (phase variable member)
20 Lock pin (rotation restricting member)
41 Surface-side balance hole (weight adjustment part)
42 Back side balance hole (weight adjustment part)

Claims (3)

A main body rotated by a crankshaft of an internal combustion engine;
A phase variable member disposed in the main body so as to be relatively rotatable and connected to a camshaft for driving the valve opening and closing, and having a rotational position adjusted in the main body in accordance with a rotation speed of the internal combustion engine; ,
A weight adjusting unit provided on one side of the main body for balancing the rotational balance in the assembly state of the main body and the phase variable member at the rotation position of the phase variable member set when the internal combustion engine is in idle operation And a cam phase varying device.   2. The cam phase varying device according to claim 1, further comprising a rotation regulating member that regulates the phase varying member at a rotation position of the idle operation when the internal combustion engine is stopped. The phase variable member is adjusted to the most retarded angle position on one end side of the rotation stroke or the most advanced angle position on the other end side of the rotation stroke during idle operation of the internal combustion engine,
3. The cam phase varying device according to claim 1, wherein the weight adjusting unit balances a rotational balance at a most retarded angle position or a most advanced angle position of the phase varying member.

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