JP2006002640A - Valve timing varying device and valve timing regulating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve timing varying device and a regulating device, which can suppress rotation fluctuation of the cam shaft of an internal combustion engine without adding control for rotation fluctuation countermeasure to control of the output of an electric motor. <P>SOLUTION: A valve timing can be advanced or delayed since the desired number of rotations can be realized for a cam shaft 6 interlocking as a result of torque being generated at a turbine impeller 24b. Since the cam shaft 6 and the electric motor 22 are interconnected by a torque converter 24 through oil, torque fluctuation on the cam shaft 6 side accompanying with valve drive is not transmitted directly to the electric motor 22 side, and on the electric motor 22 side, there is no need to apply control for rotation fluctuation countermeasure. Besides, since torque fluctuation occurring to the cam shaft 6 side is absorbed by a damper effect at the turbine impeller 24b, rotation fluctuation at the cam shaft 6 is suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a valve timing variable device and a valve timing adjusting device that change valve timing by rotating a camshaft relative to a crankshaft of an internal combustion engine.

  2. Description of the Related Art A valve timing adjusting device that changes the valve timing of an intake valve or an exhaust valve in accordance with the operating state of an internal combustion engine for combustion control of the internal combustion engine or the like is known. However, with a valve timing adjustment device that uses hydraulic pressure to change the valve timing, it is difficult to adjust the valve timing when the hydraulic pressure is insufficient at the start or at low temperatures. An apparatus that can be used has been proposed (see, for example, Patent Documents 1 and 2).

Among these, in the apparatus of Patent Document 1, the valve timing is adjusted by relatively rotating each mechanism with an electric motor using a planetary gear mechanism. In the device of Patent Document 2, by controlling the braking force of the electric motor against the camshaft, the balance point between the urging forces of the two coil springs provided between the timing pulley and the camshaft is changed to change the valve timing. It is adjusting.
Japanese Patent Laid-Open No. 11-107718 (page 4-6, FIG. 1-2) JP 2000-170513 A (page 5-7, FIG. 2-4)

  However, in the former using the planetary gear mechanism, the torque fluctuation on the camshaft side caused by the valve drive is directly transmitted to the electric motor through the meshing of the gears. In order to suppress the rotation fluctuation against such torque fluctuation and maintain the target valve timing, it is necessary to add the control for countermeasure against rotation fluctuation in the output control of the electric motor, and the control becomes complicated. This also applies to the latter using the coil spring, and torque fluctuation from the camshaft to the electric motor is directly transmitted, so it is necessary to add control for countermeasures against rotation fluctuation to the output control of the electric motor. .

  When such control for countering torque fluctuations is executed, the calculation load of an electronic control mechanism such as a CPU increases. Therefore, it becomes necessary to use an expensive electronic control mechanism, other processing is delayed, etc. This may affect the control of the entire internal combustion engine.

  An object of the present invention is to provide a valve timing variable device and a valve timing adjusting device that can suppress rotational fluctuation of a camshaft without adding rotational fluctuation countermeasure control to output control of an electric motor.

In the following, means for achieving the above object and its effects are described.
The variable valve timing device according to claim 1 is arranged in a torque transmission path between a camshaft and a crankshaft of an internal combustion engine, and changes the valve timing by rotating the camshaft relative to the crankshaft. An electric motor attached to the valve timing variable device main body or the internal combustion engine main body that rotates in conjunction with the crankshaft, and a pump impeller linked to the output shaft of the electric motor, And a fluid transmission device in which an impeller is linked to the camshaft.

  The electric motor is attached to the valve timing variable device main body or the internal combustion engine main body that rotates in conjunction with the crankshaft, and is capable of rotating the pump impeller of the fluid transmission device.

  Therefore, by rotating the pump impeller of the fluid transmission device by driving the electric motor, torque is transmitted to the turbine impeller by the fluid, and by adjusting the rotation speed and rotation angle of the turbine impeller, The rotational phase difference from the crankshaft can be changed. This makes it possible to change the valve timing by advancing or retarding the valve timing.

  Since the camshaft and the electric motor are connected via a fluid in the fluid transmission device, the torque fluctuation on the camshaft side due to the valve drive is not directly transmitted to the electric motor side, but on the electric motor side. Therefore, there is no need to add control for countermeasures against rotation fluctuations.

  In addition, since the torque fluctuation generated on the camshaft side is interlocked with the turbine impeller of the fluid transmission device, the torque fluctuation transmitted to the turbine impeller is damperd by the fluid at the blade portion of the turbine impeller. The effect is produced and absorbed. This suppresses rotational fluctuations in the camshaft.

In this way, it is possible to suppress the rotational fluctuation of the camshaft without adding the rotational fluctuation countermeasure control to the output control of the electric motor.
According to a second aspect of the present invention, there is provided the variable valve timing device according to the first aspect, wherein a stopper mechanism is provided between the camshaft and the crankshaft to limit a change range of the valve timing. .

  Due to the presence of such a stopper mechanism, the most retarded angle state and the most advanced angle state can be easily realized by simple output control such as rotating the electric motor in one direction, outputting a one-way torque, or stopping rotation in some cases. be able to.

  In addition, the stopper mechanism can prevent the valve timing from being set in an abnormal range even if the electric motor breaks down, and the camshaft can be interlocked with the crankshaft rotation, so that it is possible to save the vehicle. Become.

According to a third aspect of the present invention, in the variable valve timing device according to the first or second aspect, the fluid transmission device is a torque converter or a fluid coupling.
Thus, a torque converter or a fluid coupling can be used as the fluid transmission device. In particular, when a torque converter is used, the output torque of the electric motor is amplified and transmitted to the camshaft in addition to the effects described above, so that the effect of further reducing the size of the electric motor is produced, resulting in a large internal combustion engine. This can contribute to the reduction of energy consumption and the reduction of energy consumption when driving an electric motor.

  According to a fourth aspect of the present invention, there is provided a valve timing adjusting device according to any one of the first to third aspects, the target valve timing is set according to an operating state of the internal combustion engine, the camshaft and the crank And a valve timing adjusting unit that performs output control of the electric motor of the variable valve timing device so that a rotational phase difference from the shaft becomes a value corresponding to the target valve timing.

  As described above, the valve timing adjusting device functions as described above, so that the valve timing can be appropriately controlled without adding rotation fluctuation countermeasure control to the output control of the electric motor. Rotational fluctuation can be suppressed.

  According to a fifth aspect of the present invention, there is provided the valve timing adjusting device according to the fourth aspect, wherein the valve timing adjusting means outputs the output of the electric motor of the variable valve timing device in a direction to reduce the valve overlap when the internal combustion engine is started. Control is performed.

Thus, by controlling the valve timing adjusting means, it is possible to sufficiently secure the output torque of the internal combustion engine at the time of starting and improve the startability.
According to a sixth aspect of the present invention, in the fifth aspect, the camshaft is an intake camshaft, and the valve timing adjusting means is configured such that the cam timing is relative to the crankshaft when the internal combustion engine is started. The valve overlap is reduced by performing output control in the electric motor of the variable valve timing device in the direction of retarding the shaft.

  When adjusting the valve timing of the intake valve, by adding output control in the direction of retarding the camshaft to the electric motor at the start, the valve timing of the intake valve is retarded to reduce the valve overlap. can do.

[Embodiment 1]
FIG. 1 is a perspective view showing a valve timing adjusting device 4 for valves 2a, 2b, 2c and 2d (intake valves in the present embodiment) of an internal combustion engine to which the above-described invention is applied. In this embodiment, the valve timing adjusting device is not applied to the exhaust valve side, but a valve timing adjusting device similar to that of the intake valves 2a, 2b, 2c, 2d may be used. However, for the valve timing adjustment control of the exhaust valve, control corresponding to the exhaust valve is executed.

  The internal combustion engine here is a four-cylinder four-valve engine for a vehicle, and the camshaft 6 is provided with two cams 8a, 8b, 8c, and 8d for each cylinder. Each of the cams 8a to 8d drives the valves 2a to 2d via the roller rocker arms 10a, 10b, 10c, and 10d as the cam shaft 6 rotates. In FIG. 1, the valve seats 14a, 14b, 14c, and 14d are shown in a ring shape corresponding to the valves 2a to 2d in order to show the open / closed state of the valves 2a to 2d. Further, only the middle part of the valve springs 12a, 12b, 12c and 12d is shown.

  The rotational driving force of the camshaft 6 is obtained from the valve timing variable device 5 side incorporated in the valve timing adjusting device 4. Here, FIG. 2 shows a longitudinal section of the variable valve timing device 5.

The variable valve timing device 5 includes a timing sprocket 20, an electric motor 22, a torque converter (corresponding to a fluid transmission device) 24, and a stopper mechanism 26.
The timing sprocket 20 includes a cylindrical shaft 20a, and is supported rotatably by a journal portion J provided at one end of the cylinder head. The timing sprocket 20 is connected to the crankshaft of the internal combustion engine by a timing chain. As a result, the entire timing sprocket 20 rotates at half the rotational speed of the internal combustion engine in conjunction with the rotation of the crankshaft.

  The stopper mechanism 26 includes a housing 28 and a rotor 30 as shown in FIG. 3A corresponding to the XX cross-sectional view of FIG. The housing 28 forms the outer periphery of the stopper mechanism 26, and two inward stoppers 28a protrude from the inner circular space. The rotor 30 is a disk arranged inside the inward stopper 28a, and two outward stoppers 30a project from the outer periphery. The outward stopper 30a is disposed between the inward stoppers 28a in the circumferential direction.

  The housing 28 is formed with a bolt hole 28b in the inward stopper 28a. When the bolt 20b is screwed into the bolt hole 28b from the timing sprocket 20 side, the housing 28 is fastened to the timing sprocket 20 and integrally rotated. On the other hand, at the center of the rotor 30, the camshaft 6 that penetrates the cylindrical shaft 20 a so as to rotate is fixed by welding, spline, or the like, so that the camshaft 6 and the rotor 30 rotate integrally. Therefore, the change range of the valve timing is limited by the contact position between the inward stopper 28a and the outward stopper 30a, and the camshaft 6 can rotate relative to the timing sprocket 20 within this change range.

A cylindrical cover 26 a is formed on the torque converter 24 side from the outer periphery of the housing 28 to cover the entire torque converter 24.
The torque converter 24 has a function of amplifying the output torque of the output shaft 22 a of the electric motor 22 and transmitting it to the camshaft 6. That is, the torque converter 24 includes a pump impeller 24a, a turbine impeller 24b, and a stator 24c. Among these, the pump impeller 24 a is attached to the output shaft 22 a of the electric motor 22 and is rotated by the output of the electric motor 22. The turbine impeller 24b is attached to the camshaft 6, and the stator 24c is connected to the turbine impeller 24b or the camshaft 6 by a one-way clutch 24d.

  The main body side of the electric motor 22 is fixed to the head cover 32 of the internal combustion engine. The output of the electric motor 22 is controlled so that the target valve timing is achieved by an ECU (electronic control unit) 40 (FIG. 1) configured mainly with a microcomputer.

  That is, the ECU 40 detects the G2 signal detected every 360 ° CA (CA: crank angle) by the cam angle sensor 44 based on the rotation of the rotor 42 provided on the camshaft 6, and the engine provided on the crankshaft. The NE signal output from the rotation speed sensor 46 is detected. Based on the G2 signal and the NE signal, the cam angle θc is obtained as an advance value (for example, an advance value based on the intake TDC). Further, an intake air amount GA per unit time from the intake air amount sensor 48 and information (for example, fuel injection amount, accelerator opening degree, etc.) from other sensors and arithmetic processing are obtained, and based on these internal combustion engine operating states, A target cam angle θt corresponding to the target valve timing is calculated. The output control of the electric motor 22 is executed so that the cam angle θc becomes the target cam angle θt.

The cam angle control process is shown in the flowchart of FIG. This process is a process that is repeatedly executed at regular time intervals.
When this process is started, it is first determined whether or not the internal combustion engine has been started (S102). If it has not been started (NO in S102), it is next determined whether or not the engine is being started (S104). If the state is before cranking (NO in S104), the process is temporarily terminated as it is. For this reason, substantial processing is not performed.

  When cranking starts, that is, during starting (YES in S104), output control of the electric motor 22 is performed so that torque in the direction opposite to that during normal operation is output (S106). Therefore, torque in the direction opposite to the rotational direction of the timing sprocket 20 and the housing 28 that are linked to the crankshaft is applied to the rotor 30 of the stopper mechanism 26 via the torque converter 24. As a result, as shown in FIG. 3B, the rotor 30 of the stopper mechanism 26 rotates in the opposite direction relative to the rotation direction of the housing 28. Then, the retard side end face Lpa of the outward stopper 30 a of the rotor 30 abuts on the retard side end face Lpb of the inward stopper 28 a of the housing 28. And it stops in the pressing force state according to the reverse direction torque transmitted from the torque converter 24. FIG. Therefore, even if torque fluctuation with a large vibration width occurs in the camshaft 6 during cranking, the contact state between the retard side end face Lpa and the retard side end face Lpb is maintained. Further, since the turbine impeller 24b interlocked with the camshaft 6 produces a damper effect by the oil (corresponding to fluid) in the torque converter 24 and the rotational fluctuation of the camshaft 6 is suppressed, the retarded side end face Lpa is more reliably detected. The contact state with the retarded side end face Lpb is maintained.

  The contact state between the retard side end surface Lpa and the retard side end surface Lpb corresponds to a state where the valve timing of the intake valve 2a is at the most retarded angle. As a result, it is possible to reliably maintain a state in which the valve overlap is the smallest at the time of starting, that is, a state in which there is no valve overlap. As a result, a sufficient amount of intake air into the combustion chamber is secured, and stable engine start can be performed quickly.

  When the start of the internal combustion engine is completed (YES in S102), in order to obtain a valve timing corresponding to the operation state of the internal combustion engine, from the values of the operation state of the internal combustion engine (engine speed NE, intake air amount GA, etc.) A target cam angle θt is calculated based on the target cam angle map obtained by experiments or the like (S108).

Next, a difference dθ between the target cam angle θt and the actually detected cam angle θc is calculated as shown in Equation 1 (S110).
[Formula 1] dθ ← θt − θc
Next, the state of the difference dθ is determined (S112). Here, if dθ <0 (°), that is, at the time of requesting the retard control of the valve timing, the ECU 40 executes a positive torque output reduction process of the electric motor 22 (S114). As a result, when the actual cam angle θc is advanced from the target cam angle θt, the cam angle θc is decreased toward the target cam angle θt.

After starting, the control of the electric motor 22 is based on the premise that the rotation of the camshaft 6 is adapted to the rotation of the timing sprocket 20 by a positive torque output.
On the other hand, if dθ> 0, that is, when the valve timing advance control is requested, the ECU 40 executes a positive torque output increase process of the electric motor 22 (S116). As a result, when the actual cam angle θc is retarded from the target cam angle θt, the cam angle θc is increased toward the target cam angle θt.

If dθ = 0, the ECU 40 maintains the cam angle θc by causing the electric motor 22 to maintain a positive torque output level.
In the configuration described above, the relationship with the claims corresponds to the cam angle control processing (FIG. 4) as processing as the valve timing adjusting means.

According to the first embodiment described above, the following effects can be obtained.
(I). The electric motor 22 is attached to the internal combustion engine body by being fixed to the head cover 32 of the internal combustion engine. In this state, the electric motor 22 can rotate the pump impeller 24 a of the torque converter 24.

  For this reason, when the electric motor 22 rotates the pump impeller 24a, torque is generated in the turbine impeller 24b, and a desired rotational speed can be realized in the camshaft 6 interlocked with the turbine impeller 24b. Thus, the rotational phase difference between the camshaft 6 and the crankshaft can be changed, and the valve timing can be advanced or retarded.

  Since the camshaft 6 and the electric motor 22 are connected to each other through oil as a fluid in the torque converter 24, torque fluctuation on the camshaft 6 side accompanying valve driving is directly transmitted to the electric motor 22 side. There is no. Therefore, as described in the cam angle control process (FIG. 4), it is not necessary to add control for countermeasures against rotation fluctuation in the control on the electric motor 22 side.

  Moreover, since the torque fluctuation generated on the camshaft 6 side is interlocked with the turbine impeller 24b of the torque converter 24, the torque fluctuation transmitted to the turbine impeller 24b is the blade of the turbine impeller 24b. Damper effect is caused by oil in the part and absorbed. As a result, rotational fluctuations in the camshaft 6 are suppressed.

Thus, the rotation fluctuation of the camshaft 6 can be suppressed without adding the rotation fluctuation countermeasure control to the output control of the electric motor 22.
(B). Due to the presence of the stopper mechanism 26, the most retarded angle state or the most advanced angle state can be easily achieved by simple output control such as rotating the electric motor 22 in one direction, outputting torque in one direction, or stopping rotation in some cases. Can be realized.

  Here, the reverse torque is output to the electric motor 22 at the time of starting, so that the retarded end face Lpa of the outward stopper 30a of the rotor 30 is brought into contact with the retarded end face Lpb of the inward stopper 28a of the housing 28, so The corner state is realized. Further, by adding the damper effect, it is possible to easily maintain the state without the valve overlap due to the most retarded state, and to sufficiently secure the output torque of the internal combustion engine at the time of starting, thereby improving the startability.

  Further, the stopper mechanism 26 can prevent the valve timing from being set in an abnormal range even if the electric motor 22 fails, and the camshaft 6 can be interlocked with the rotation of the crankshaft. Become.

  (C). Since the torque converter 24 is used as the fluid transmission device, the output torque of the electric motor 22 is amplified and transmitted to the camshaft 6. As a result, the effect of further reducing the size of the electric motor 22 is produced, which can contribute to the suppression of the increase in size of the entire internal combustion engine and the reduction of energy consumption when the electric motor 22 is driven.

[Embodiment 2]
In the present embodiment, as shown in FIG. 5, the electric motor 122 is fixed to a cylindrical cover 126a. That is, the electric motor 122 is attached to the main body of the variable valve timing device 105. Therefore, the electric motor 122 rotates in conjunction with the timing sprocket 20.

  For this reason, electric power is supplied to the electric motor 122 by contact between the ring-like electrode 123 provided on the electric motor 122 side and the brush-like electrode 133 provided on the internal combustion engine side such as the head cover 132. Other configurations are the same as those in the first embodiment, and are denoted by the same reference numerals.

  On the ECU side, the aforementioned cam angle control process (FIG. 4) is executed. However, since the electric motor 122 rotates together with the timing sprocket 20, the electric motor 122 is controlled in a relatively low rotation state.

According to the second embodiment described above, the following effects can be obtained.
(I). Although the electric motor 122 is attached to the cover 126a and rotates together with the timing sprocket 20, there is a difference in configuration in which the rotation angle is adjusted not by the rotation speed of the turbine impeller 24b by the rotation of the pump impeller 24a. The effects (a) to (c) of the first embodiment are produced.

  However, since the electric motor 122 is controlled at a lower speed than in the case of the first embodiment and is not affected by a change in the rotational speed of the internal combustion engine, more stable valve timing adjustment is possible.

[Other embodiments]
(A). In each of the above embodiments, the torque converter is used as the fluid transmission device, but a fluid coupling without a stator may be used. In this case, there is no torque amplification effect, but the valve timing can be adjusted by coping with the increase in output torque on the electric motor side.

  (B). In each of the above embodiments, the stopper mechanism is used. However, a state in which there is no valve overlap by driving the electric motor without starting the stopper mechanism may be realized.

1 is a perspective view of a valve timing adjustment device for an internal combustion engine according to Embodiment 1. FIG. FIG. 3 is a longitudinal sectional view of the variable valve timing device according to the first embodiment. FIG. 3 is a diagram illustrating the configuration and operation of the stopper mechanism according to the first embodiment. 5 is a flowchart of cam angle control processing executed by the ECU according to the first embodiment. The longitudinal cross-sectional view of the valve timing variable apparatus of Embodiment 2. FIG.

Explanation of symbols

  2a, 2b, 2c, 2d ... intake valve, 4 ... valve timing adjusting device, 5 ... valve timing variable device, 6 ... camshaft, 8a, 8b, 8c, 8d ... cam, 10a, 10b, 10c, 10d ... roller rocker Arm, 12a, 12b, 12c, 12d ... Valve spring, 14a, 14b, 14c, 14d ... Valve seat, 20 ... Timing sprocket, 20a ... Cylindrical shaft, 20b ... Bolt, 22 ... Electric motor, 22a ... Output shaft, 24 ... Torque converter, 24a ... pump impeller, 24b ... turbine impeller, 24c ... stator, 24d ... one-way clutch, 26 ... stopper mechanism, 26a ... cylindrical cover, 28 ... housing, 28a ... inward stopper, 28b ... bolt hole 30 ... rotor, 30a ... outward stopper, 32 ... 40 ... ECU, 42 ... rotor, 44 ... cam angle sensor, 46 ... engine speed sensor, 48 ... intake air amount sensor, 105 ... valve timing variable device, 122 ... electric motor, 123 ... ring electrode, 126a ... cover , 132... Head cover, 133... Brush-like electrode, J.

Claims (6)

A variable valve timing device arranged in a torque transmission path between a camshaft and a crankshaft of an internal combustion engine and changing a valve timing by rotating the camshaft relative to the crankshaft;
An electric motor attached to the valve timing variable device main body or the internal combustion engine main body rotating in conjunction with the crankshaft;
A fluid transmission device in which a pump impeller is linked to an output shaft of the electric motor, and a turbine impeller is linked to the camshaft;
A variable valve timing device comprising: 2. The variable valve timing device according to claim 1, wherein a stopper mechanism is provided between the camshaft and the crankshaft to limit a valve timing change range. 3. The variable valve timing device according to claim 1, wherein the fluid transmission device is a torque converter or a fluid coupling. The valve timing variable device according to any one of claims 1 to 3,
The target valve timing is set according to the operating state of the internal combustion engine, and the electric motor of the valve timing variable device is set so that the rotational phase difference between the camshaft and the crankshaft becomes a value corresponding to the target valve timing. Valve timing adjusting means for performing motor output control;
A valve timing adjusting device comprising: 5. The valve timing adjusting device according to claim 4, wherein the valve timing adjusting means performs output control in the electric motor of the valve timing variable device in a direction to reduce the valve overlap when the internal combustion engine is started. . 6. The variable valve timing device according to claim 5, wherein the camshaft is an intake camshaft, and the valve timing adjusting means is configured to retard the camshaft with respect to the crankshaft when the internal combustion engine is started. A valve timing adjusting device characterized in that the valve overlap is reduced by performing output control in the electric motor.

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