Valve opening and closing timing control device

Abstract

A valve opening / closing timing control device includes a driving-side rotary body, a driven-side rotary body, an electric motor that controls a relative rotation phase, a phase sensor, and a phase control section. The valve opening / closing timing control device has an abutting phase that becomes a mechanical limit at which a driving-side abutting section and a driven-side abutting section abut. The relative rotation phase fluctuates by a prescribed amplitude, and the valve opening / closing timing control device includes a target phase correction section that sets a correction target phase as a new target phase, the correction target phase being a phase at which even if the relative rotation phase fluctuates by the prescribed amplitude, the relative rotation phase does not reach the abutting phase and a gap is formed between the driving-side abutting section and the driven-side abutting section when the target phase is set to the abutting phase or when the target phase is set to a phase at which the relative rotation phase reaches the abutting phase by fluctuation of the relative rotation phase by the prescribed amplitude.

Description

Technical Field

[0001] This invention relates to a valve opening and closing timing control device. Background Technology

[0002] As a valve opening and closing period control device, it includes: a drive-side rotating body that rotates synchronously with a crankshaft; a driven-side rotating body that rotates integrally with a camshaft; a phase sensor that detects the relative rotation phase of the drive-side rotating body and the driven-side rotating body; and a drive mechanism that controls the relative rotation phase. As in Patent Document 1 or Patent Document 2 below, it has a structure that learns by using a predetermined rotation phase to correct the error between the relative rotation phase (actual phase) and the detected phase detected by the phase sensor.

[0003] The valve opening and closing timing control device (valve timing control device) of Patent Document 1 includes a driven side rotating body (camshaft component) and a drive side rotating body (cam pulley) supported on the driven side rotating body, and has an intermediate component that helically engages with the drive side rotating body and the driven side rotating body, and a drive mechanism that moves axially toward the intermediate component by hydraulic pressure.

[0004] In the valve opening and closing timing control device of Patent Document 1, the relative rotation phase is detected by signals from multiple sensors, and a reference phase of the relative rotation phase (e.g., the maximum advance angle phase or the maximum lag angle phase) is set during idling to learn the reference phase.

[0005] Furthermore, in the valve opening and closing timing control device (variable valve timing control device) of Patent Document 2, learning is performed at the moment when the relative rotation phase is set as the reference phase (e.g., the maximum advance angle phase or the maximum lag angle phase) and at the moment when the phase is near the reference phase.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 6-299876

[0009] Patent Document 2: Japanese Patent Application Publication No. 2012-41901

[0010] The technical problem that the invention aims to solve

[0011] The valve opening and closing timing control device has a structure in which the contact portion of the driving-side rotating body abuts against the contact portion of the driven-side rotating body to determine the maximum advance angle phase and the maximum lag angle phase. In addition, in order to set the relative rotation phase, a structure with a drive mechanism that transmits the driving force of the electric motor through a reduction gear has been developed.

[0012] During engine operation, the intake and exhaust camshafts rotate at relatively short cycles in the acceleration and deceleration directions due to the torque generated by the camshafts. Consequently, the relative rotational phase between the driven and driven rotating parts connected to the camshafts also varies at relatively short cycles in the advance and lag directions. In phase control, when the relative rotational phase is set to the maximum lag or maximum advance phase, the abutment structure repeatedly experiences states of contact and separation between the abutment parts.

[0013] In particular, in a drive mechanism with a reduction gear that sets a relative rotational phase, it is also considered that when the rotational speed of the camshaft changes due to the change in the torque of the cam, the load on the reduction gear increases at the moment when the two contact parts come into contact, which may cause the teeth of the reduction gear to break or cause the drive mechanism to malfunction. Summary of the Invention

[0014] Based on this reasoning, the present invention provides a valve opening and closing timing control device that will not cause malfunction of the drive mechanism even when the relative rotation phase is set at or near the end of the control area.

[0015] Technical means for solving technical problems

[0016] The valve opening / closing timing control device of the present invention is characterized by comprising: a drive-side rotating body that rotates freely about a rotation axis and synchronously with the crankshaft of an internal combustion engine; a driven-side rotating body that rotates freely about the rotation axis and integrally with the camshaft of the internal combustion engine for valve opening / closing; an electric motor and a reduction gear for controlling the relative rotational phase of the drive-side rotating body and the driven-side rotating body; a phase sensor that detects the relative rotational phase as the actual phase; and a phase control unit that controls the electric motor in a direction that reduces the phase difference between the actual phase and the target phase when a target phase is set, and the valve opening / closing timing control device is configured to have an abutment phase, which is a phase that is connected to the valve opening / closing timing control device. The phase that becomes the mechanical limit of the relative rotation phase by abutting the driving-side abutting portion formed on the driving-side rotating body and the driven-side abutting portion formed on the driven-side rotating body, the relative rotation phase changing by a predetermined amplitude, the valve opening and closing period control device having a target phase correction unit, the target phase correction unit replacing the target phase and setting a corrected target phase as the new target phase, the corrected target phase being a phase in which the relative rotation phase does not reach the abutting phase even if the relative rotation phase changes by the predetermined amplitude, when the target phase is set to the abutting phase, or when the target phase is set to the phase in which the relative rotation phase reaches the abutting phase by changing by the predetermined amplitude, and a gap is formed between the driving-side abutting portion and the driven-side abutting portion.

[0017] According to this feature structure, when the target phase is set to the contact phase, or when the target phase is set to the phase where the relative rotation phase reaches the contact phase through a predetermined amplitude variation, the target phase correction unit replaces the target phase and resets the corrected target phase to a new target phase. This corrected target phase is a phase in which a gap is formed between the driving side contact portion and the driven side contact portion even if the relative rotation phase shifts in the direction of approach due to the predetermined amplitude variation. That is, the target phase is not limited to the phase where the driving side contact portion and the driven side contact portion are in contact; even if the driving side contact portion and the driven side contact portion are not in contact, when they are in contact phase due to the cam's variable torque, the corrected target phase is set to a new target phase instead of the target phase. As a result, the state in which the driving side contact portion and the driven side contact portion are separated can be maintained, and the undesirable situation where the driving side contact portion and the driven side contact portion are in contact due to the cam's variable torque can be suppressed.

[0018] Therefore, a valve opening and closing timing control device is constructed that will not cause the drive mechanism to malfunction even if the relative rotation phase is set at the end or near the end of the control area.

[0019] As an addition to the above structure, the target phase correction unit may set the correction target phase based on the contact phase after the phase sensor detects that the relative rotation phase has reached the contact phase.

[0020] Therefore, after the phase sensor detects that the relative rotation phase has reached the contact phase, the target phase correction unit can set the correction target phase based on the contact phase.

[0021] As an addition to the above structure, the phase control unit may perform contact control, which causes the relative rotation phase to shift to a phase in which the driving side contact portion and the driven side contact portion come into contact, while the phase phase varies by the predetermined amplitude. In this contact control, the phase sensor detects that the actual phase changes repeatedly by the predetermined amplitude over time in the direction in which the driving side contact portion and the driven side contact portion separate and in the direction in which the driving side contact portion and the driven side contact portion approach each other, and sets the actual phase when the driving side contact portion and the driven side contact portion are closest as the contact phase.

[0022] Therefore, by performing contact control, the actual phase change detected by the phase sensor is obtained according to the passage of time. This allows the displacement of the drive-side contact part and the driven-side contact part in the direction of separation and the displacement of the drive-side contact part and the driven-side contact part in the direction of approach due to the change torque of the cam to be obtained. The actual phase in the obtained actual phase when the drive-side contact part and the driven-side contact part are in the closest state is set as the contact phase.

[0023] As an addition to the above structure, it may also include: a rotation sensor that detects a signal corresponding to the rotation angle of the motor; and an angular velocity calculation unit that calculates the angular velocity based on the signal corresponding to the rotation angle detected by the rotation sensor, wherein the phase control unit performs contact control to bring the drive-side contact portion into contact with the driven-side contact portion, and in this contact control, when the waveform representing the change in the angular velocity calculated by the angular velocity calculation unit changes, the actual phase detected by the phase sensor is set as the contact phase.

[0024] When the driving-side contact portion and the driven-side contact portion are separated, the load on the motor is low, and the angular velocity calculated by the angular velocity calculation unit based on the rotation angle detected by the rotation sensor hardly changes. In contrast, when the driving-side contact portion and the driven-side contact portion are brought into contact through contact control, the angular velocity changes due to the increased load on the motor. Based on this change in angular velocity, the arrival of the contact phase can be detected, and the actual phase of this waveform change can be set as the contact phase.

[0025] As an addition to the above structure, it may also include a current sensor that detects the current supplied to the motor, and the phase control unit performs contact control to make the drive-side contact part contact with the driven-side contact part. In this contact control, when the current detected by the current sensor increases, the actual phase detected by the phase sensor is set as the contact phase.

[0026] When the drive-side contact portion and the driven-side contact portion reach contact through contact control, the load acting on the motor increases, and the current detected by the current sensor increases. Based on this reasoning, the actual phase of the current rise detected by the current sensor is the contact phase, and this actual phase of the current rise detected by the current sensor can be set as the contact phase.

[0027] As an addition to the above structure, the target phase correction unit may use the phase obtained by adding a phase corresponding to a value greater than 1 / 2 of the variation amplitude when the relative rotation phase changes by the predetermined amplitude to the target phase as the corrected target phase.

[0028] When the camshaft rotates, the rotational phase of the camshaft changes with a predetermined amplitude and a short period in the advance angle and lag angle directions due to the cam's variable torque. Based on this reasoning, even if the target phase correction unit sets the correction target phase using the actual phase that would cause the drive-side contact portion and the driven-side contact portion to contact as a reference, and uses a phase obtained by adding more than half of the relative rotational phase variation amplitude to the target phase as the correction target phase, thus suppressing undesirable contact between the drive-side contact portion and the driven-side contact portion due to the cam's variable torque causing them to move closer to each other, it is possible to suppress such contact problems. Attached Figure Description

[0029] Figure 1 It is a diagram showing the cross-section of the engine and the control unit.

[0030] Figure 2 This is a cross-sectional view of the main working body of the control device during valve opening and closing.

[0031] Figure 3 yes Figure 2 Sectional view along line III-III.

[0032] Figure 4 This is a cross-sectional view of the contact structure where the driven side contact portion is located at the outer contact phase on the advance angle side.

[0033] Figure 5 This is a cross-sectional view of the contact structure where the driven side contact part is located on the advance angle side to correct the target phase.

[0034] Figure 6 This is a cross-sectional view of the contact structure where the driven side contact portion is located at the outer contact phase of the hysteresis angle.

[0035] Figure 7 This is a cross-sectional view of the contact structure where the driven side contact part is located on the hysteresis angle side to correct the target phase.

[0036] Figure 8 This is a flowchart of phase control.

[0037] Figure 9 This is a flowchart of the contact phase detection procedure.

[0038] Figure 10 It is a timing diagram that represents the phase change and current under non-contact phase conditions.

[0039] Figure 11 It is a timing diagram that represents the phase change and current under the contact phase.

[0040] Figure 12 This is a flowchart of the contact phase detection procedure for another implementation method (a). Detailed Implementation

[0041] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0042] (Basic Structure)

[0043] like Figure 1 As shown, engine E, which is an internal combustion engine, has an intake valve Va and an exhaust valve Vb, and also has a valve opening and closing timing control device A for setting the valve timing (opening and closing period) of the intake valve Va. This engine E (an example of an internal combustion engine) represents the structure of a vehicle such as a passenger car for obtaining driving force.

[0044] In addition, the valve opening and closing timing control device A can also be a structure that sets the opening and closing timing of the exhaust valve Vb, or it can be a structure that has two valve opening and closing timing control devices A for the engine E, so as to set the opening and closing timing of the intake valve Va and the exhaust valve Vb separately.

[0045] The engine E and the valve opening / closing timing control device A are controlled by the engine control unit 40. In particular, the valve opening / closing timing control device A consists of a working body Aa and a control unit Ab. The working body Aa is made of hardware that determines the valve timing of the intake valve Va by the driving force of a phase control motor M (an example of an electric motor) configured as a brushless DC motor. The control unit Ab contains the software of the engine control unit 40 to control the phase control motor M.

[0046] like Figure 2 As shown, the main working body Aa of the valve opening and closing period control device A has a drive housing 21 (driving-side rotating body) and an internal rotor 22 (driven-side rotating body). The relative rotational phase (hereinafter referred to as "relative rotational phase") between the drive housing 21 and the internal rotor 22 is controlled by reducing and transmitting the driving force of the phase control motor M via the reduction gear G. In this valve opening and closing period control device A, the phase control motor M (electric motor) and the reduction gear G are referred to as the drive mechanism.

[0047] like Figure 1 As shown, the control unit Ab has the following software: the software controls the phase control motor M based on the signal of the phase sensor PS, etc. in the engine control unit 40, thereby controlling the valve timing of the intake valve Va.

[0048] like Figure 1 , Figure 2 As shown, the phase sensor PS consists of a crankshaft angle sensor 16 that detects the rotation angle of the crankshaft 1 and a cam angle sensor 17 that detects the rotation angle of the intake camshaft 7 (an example of a camshaft for valve opening and closing). The relative rotational phase between the drive housing 21 and the internal rotor 22 is the relative angle between the drive housing 21 and the internal rotor 22 centered on the rotation axis X, and the valve timing (opening and closing period) of the intake valve Va changes by changing this relative rotational phase. In particular, the relative rotational phase detected by the phase sensor PS is referred to as the actual phase.

[0049] like Figure 1 As shown, engine E connects cylinder head 3 to the upper part of cylinder block 2, which supports crankshaft 1. In addition, engine E houses piston 4 in multiple cylinder bores formed in cylinder block 2, and connects piston 4 to crankshaft 1 via connecting rod 5 to form a four-stroke type.

[0050] The cylinder head 3 is provided with an intake valve Va and an exhaust valve Vb. The upper part of the cylinder head 3 is provided with an intake camshaft 7 (an example of a camshaft for valve opening and closing) that controls the intake valve Va and an exhaust camshaft 8 that controls the exhaust valve Vb. In addition, the timing belt 6 is wound around the output pulley 1S of the crankshaft 1, the drive pulley 21S of the working body Aa, and the exhaust pulley VbS of the exhaust valve Vb.

[0051] The cylinder head 3 is equipped with an injector 9 for injecting fuel into the fuel chamber and an ignition plug 10. The cylinder head 3 is provided with an intake manifold 11 that supplies air to the combustion chamber via an intake valve Va and an exhaust manifold 12 that sends combustion gases from the combustion chamber out via an exhaust valve Vb.

[0052] The crankshaft angle sensor 16 is configured to output pulse signals as the crankshaft 1 rotates. By counting the pulse signals based on the rotation reference of the crankshaft 1, the rotation angle based on the rotation reference angle can be obtained. Similarly, the camshaft angle sensor 17 is configured to count the pulse signals (pulse signals output by the crankshaft angle sensor 16) based on the rotation reference of the intake camshaft 7 as the intake camshaft 7 rotates, thereby obtaining the rotation angle based on the rotation reference of the intake camshaft 7.

[0053] As described above, the phase sensor PS is composed of a crankshaft angle sensor 16 and a cam angle sensor 17. According to this structure, in order to detect the relative rotational phase by means of the phase sensor PS, for example, by storing the rotational reference count values ​​of the drive housing 21 and the internal rotor 22 in a predetermined reference phase (e.g., intermediate phase) state according to the crankshaft angle sensor 16 and the cam angle sensor 17, the actual phase can be obtained by comparing the two count values ​​regardless of whether the relative rotational phase changes from the reference phase towards the advance angle side or the lag angle side. Based on this principle, the detection of the actual phase is realized in the phase sensor PS.

[0054] As described above, the engine control unit 40 constitutes a control unit Ab as an ECU for controlling the engine E. The engine control unit 40 will be described in detail below.

[0055] (Control device for valve opening and closing: main working body)

[0056] like Figure 2 As shown, the working body Aa arranges the drive box 21 (driving side rotating body) and the internal rotor 22 (driven side rotating body) coaxially with the rotation axis X of the intake camshaft 7. In order to set these relative rotation phases, a phase control motor M and a reduction gear G are provided as the aforementioned drive mechanism.

[0057] The drive housing 21 has a drive pulley 21S formed on its outer periphery. The inner rotor 22 is enclosed in the drive housing 21 and is connected and fixed to the intake camshaft 7 by connecting bolts 23. With this structure, the drive housing 21 is rotatably supported on the outer periphery of the inner rotor 22.

[0058] like Figure 1As shown, driven by the timing belt 6, the working body Aa rotates in the driving rotation direction S. Additionally, the driving force of the phase-controlled motor M is transmitted to the internal rotor 22 via the reduction gear G, causing a change in the relative rotational phase of the internal rotor 22 relative to the drive housing 21. The displacement direction in which this change occurs, in the same direction as the driving rotation direction S, is called the advance angle direction Sa, and its opposite direction is called the lag angle direction Sb. Valve timing is controlled as follows: by changing the relative rotational phase towards the advance angle direction Sa, the intake timing is advanced; by changing the relative rotational phase towards the lag angle direction Sb, the intake timing is delayed.

[0059] The reduction gear G reduces the rotational driving force of the phase control motor M to achieve displacement of the relative rotational phase between the drive housing 21 and the internal rotor 22. That is, when the engine E is running, the output shaft MS of the phase control motor M is driven to rotate in the same direction as the intake camshaft 7 and the drive rotation direction S, thereby maintaining the relative rotational phase of the valve opening and closing control device A. Conversely, decreasing the speed of the output shaft MS changes the relative rotational phase towards the advance angle direction Sa, while increasing the speed of the output shaft MS changes the relative rotational phase towards the lag angle direction Sb.

[0060] (Drive structure)

[0061] A reduction gear G is disposed between the drive housing 21 and the internal rotor 22. A front plate 24 is fastened to the opening of the drive housing 21 by a plurality of fastening bolts 25. Thus, the displacement of the reduction gear G and the internal rotor 22 in the direction along the rotation axis X is restricted by the front plate 24.

[0062] The reduction gear G includes: a gear ring 26, which is coaxially formed on the inner circumference of the inner rotor 22 with the rotation axis X; an internal gear 27, which is rotatably disposed on the inner circumference of the inner rotor 22 with an eccentric axis Y parallel to the rotation axis X. Furthermore, to enable the reduction gear G to function, it includes: an eccentric cam body 28, which is disposed on the inner circumference of the internal gear 27 and has a cam surface formed on its outer surface; a front plate 24; and a cross-shaped connector J. The eccentric cam body 28 is rotatably supported on the front plate 24 by a first bearing 31.

[0063] The gear ring 26 has multiple internal tooth portions 26T, and the internal gear 27 has multiple external tooth portions 27T, a portion of which meshes with the internal tooth portions 26T of the gear ring 26. This reduction gear G is configured as an internal tangential planetary gear reducer where the number of teeth on the external tooth portions 27T of the internal gear 27 is only one less than the number of teeth on the internal tooth portions 26T of the gear ring 26.

[0064] An eccentric cam body 28 has a circular eccentric cam surface 28A centered on an eccentric axis Y on its outer periphery, and an internal gear 27 is rotatably supported on the eccentric cam surface 28A via a second bearing 32. A phase control motor M is supported on the engine E, such that a locking pin 34 formed on the output shaft MS engages with a pair of locking grooves 28B on the inner periphery of the eccentric cam body 28. Although the detailed structure is not shown, the phase control motor M includes: a rotor with permanent magnets, a stator with multiple excitation coils arranged around the rotor, and an output shaft MS that transmits the rotation of the rotor.

[0065] In this drive structure, when the eccentric cam body 28 rotates around the rotation axis X via the phase control motor M, the internal gear 27 rotates relative to the gear ring 26 by an angle corresponding to the difference in the number of teeth for each revolution. As a result, the drive housing 21, which rotates integrally with the internal gear 27 via the joint J, and the intake camshaft 7, which is connected to the gear ring 26 via the connecting bolt 23, rotate relative to each other, thereby achieving a displacement of the relative rotational phase between the drive housing 21 and the internal rotor 22.

[0066] (Abutment structure)

[0067] In particular, such as Figure 3 As shown, the working body Aa has an abutment structure 35, which sets an advance angle-side abutment phase Pa (generally, an example of the maximum advance angle phase and abutment phase) where the relative rotational phase is the mechanical limit in the advance angle direction Sa, and a lag angle-side abutment phase Pb (generally, an example of the maximum lag angle phase and abutment phase) where the relative rotational phase is the mechanical limit in the lag angle direction Sb. The abutment structure 35 has a drive-side abutment portion 35a integrally formed with the drive housing 21 and a driven-side abutment portion 35b integrally formed with the internal rotor 22. Furthermore, the advance angle-side abutment phase Pa and the lag angle-side abutment phase Pb are also included in the vicinity of each other and reach the advance angle-side abutment phase Pa and the lag angle-side abutment phase Pb due to the action of the cam's variable torque.

[0068] That is, an opening is formed in the wall portion 21w of the drive housing 21 in an orientation orthogonal to the rotation axis X. A pair of drive-side abutment portions 35a are formed at positions separated in the circumferential direction centered on the rotation axis X on the inner periphery of this opening. Furthermore, the driven-side abutment portion 35b is formed to pass through the opening of the wall portion 21w of the drive housing 21 in the inner rotor 22, and abuts against one of the drive-side abutment portions 35a when the relative rotational phase reaches the advance angle abutment phase Pa, and abuts against the other drive-side abutment portion 35a when the relative rotational phase reaches the lag angle abutment phase Pb.

[0069] When engine E is running, the intake camshaft 7 and exhaust camshaft 8 of engine E rotate at speeds that change in a short period of time, moving in the direction of acceleration and deceleration, due to the torque of the camshafts. Therefore, the relative rotational phase between the internal rotor 22 connected to camshafts 7 and 8 and the drive housing 21 also changes in a short period of time, moving in the advance angle direction Sa and the lag angle direction Sb. In phase control, when the relative rotational phase is set to the advance angle side contact phase Pa or the lag angle side phase Pb, the driving side contact portion 35a and the driven side contact portion 35b of the contact structure 35 repeatedly engage and disengage.

[0070] (Control Structure)

[0071] like Figure 1 As shown, detection signals from crankshaft angle sensor 16 and camshaft angle sensor 17 are respectively input to engine control unit 50. Additionally, engine control unit 40 outputs control signals to motor control unit 47, which controls phase control motor M, and inputs detection signals from rotation sensor RS, which is built into phase control motor M, and current signals supplied from motor control unit 47 to phase control motor M. Rotation sensor RS outputs a signal corresponding to the rotation angle of phase control motor M.

[0072] As described above, the intake camshaft 7 experiences a relative rotational phase variation within a specified range in the advance angle direction Sa and the lag angle direction Sb due to the cam's variable torque. The engine control unit 40 acquires this variation (variation of angular velocity) based on the detection signal from the rotation sensor RS built into the phase control motor M. The rotation sensor RS is assumed to output a detection signal whenever the output shaft MS of the phase control motor M reaches a specified rotation angle, and the detection signal is output to the engine control unit 40.

[0073] The engine control unit 40 includes an operation control unit 41, and further includes a phase control unit 42, a contact phase detection unit 43, a target phase setting correction unit 44, a target phase correction unit 45, and an angular velocity calculation unit 46. These components are configured as software, but some may also be configured as hardware such as logic circuits. In this structure, the control unit Ab is composed of the phase control unit 42, the contact phase detection unit 43, the target phase setting correction unit 44, the target phase correction unit 45, and the angular velocity calculation unit 46. Additionally, the engine control unit 40 includes a non-volatile memory (not shown) such as an EEPROM.

[0074] The operation control unit 41 controls the operation of the engine E by managing the fuel injection of the injector 9 and the ignition of the ignition plug 10. The phase control unit 42 sets the target phase of the valve opening and closing period control device A in accordance with the amount of accelerator pedal (not shown) operation and the load acting on the driving system, and performs phase control to make the actual phase consistent with the target phase by controlling the phase control motor M in the direction of reducing the phase difference (deviation) between the actual phase detected by the phase sensor PS (crankshaft angle sensor 16, cam angle sensor 17) and the target phase.

[0075] The contact phase detection unit 43 performs contact control and detects the advance angle-side contact phase Pa and the lag angle-side contact phase Pb, which are mechanically limited by the relative rotation phase. This contact control drives the phase control motor M until the drive-side contact part 35a and the driven-side contact part 35b come into contact when the phase control of the phase control unit 42 is executed.

[0076] The target phase setting unit 44 sets the target phase based on the contact phase detected by the contact phase detection unit 43, and based on the change in angular velocity calculated by the angular velocity calculation unit 46 of the rotation sensor RS. Figure 5 The example shown is the advance angle side correction target phase Pac (an example of target phase correction) and Figure 7 The hysteresis angle side correction target phase Pbc shown is an example of a corrected target phase.

[0077] The corrected target phase (advance angle side corrected target phase Pac, lag angle side corrected target phase Pbc) is as follows: even if the relative rotation phase changes by a specified amplitude due to the cam's variable torque, the relative rotation phase does not reach the contact phase (advance angle side contact phase Pa, lag angle side contact phase Pb), and a gap is formed between the drive-side contact portion 35a and the driven-side contact portion 35b.

[0078] When executing phase control, the target phase correction unit 45, in cases where the target phase is set to an abutment phase or where the target phase is set to reach the abutment phase through a change within a predetermined range of relative rotation phase, corrects the target phase instead of the target phase. Figure 5 The target phase Pac shown is corrected by the advance angle side. Figure 7 The target phase Pbc shown is set as the new target phase.

[0079] The angular velocity calculation unit 46 calculates the angular velocity of the output shaft MS of the phase control motor M based on the signal corresponding to the rotation angle detected by the rotation sensor RS.

[0080] (Control method: Phase control)

[0081] like Figure 8 As shown in the flowchart, in phase control, the contact phase detection procedure is executed (step #200). Next, the target phase setting unit 44 acquires the change in the relative rotation phase under the action of the cam's variable torque, calculates the value of the target phase correction (the target phase correction Pac on the advance angle side and the outer contact phase Pbs on the lag angle side) based on this acquisition, and stores it in the memory (step #100).

[0082] The control of step #101 will be explained in detail below. When engine E is running, due to the torque variation of the camshaft, the speed of the intake camshaft 7 increases or decreases in the advance and lag directions with a short period and a specified amplitude. Therefore, the relative rotational phase also varies (angular velocity variation) in the advance and lag directions with a specified amplitude. Thus, for example, when the relative rotational phase shifts from the intermediate phase towards the advance angle side, the relative rotational phase reaches... Figure 3 Before the phase Pa is brought into contact with the leading angle side as shown, in Figure 4 The phase between the advance angle side outer contact phase Pas and the advance angle side contact phase Pa, as shown, means that the driving side contact part 35a and the driven side contact part 35b also repeatedly contact and separate with a shorter period.

[0083] exist Figure 10 In the upper section, the reference waveform Ts represents the change in angular velocity calculated by the angular velocity calculation unit 46. In the same figure, the horizontal axis represents the passage of time, and the vertical axis represents the amount of phase change caused by the action of the cam's changing torque. The reference waveform Ts is a sine wave, representing the change in angular velocity relative to the rotational phase. In this control, the phase angle corresponding to 1 / 2 (amplitude Tb) of the vibration amount Ta of the reference waveform Ts is represented as the outer contact phase Pas on the advance angle side, which is displaced in the lag angle direction relative to the advance angle side contact phase Pa.

[0084] In a relative rotation phase that is further displaced by a set phase in the lag direction than the advance angle side outer contact phase Pas, it is possible to reliably prevent contact between the driving side contact portion 35a and the driven side contact portion 35b. Therefore, this relative rotation phase is set as follows: Figure 5 The advance angle side correction target phase Pac is shown. Furthermore, in the advance angle side correction target phase Pac, even when the driving side abutment portion 35a and the driven side abutment portion 35b are closest, a gap is formed between them.

[0085] Based on the same considerations as previously described for the advance angle side contact phase Pa, the advance angle side outer contact phase Pas, and the advance angle side corrected target phase Pac, the following is set... Figure 6 The hysteresis angle side external contact phase Pbs shown is Figure 7 The target phase Pbc is shown as the hysteresis angle side correction.

[0086] That is, when the phase rotation phase is shifted from the intermediate phase to the lag angle side, before the relative rotation phase reaches the lag angle side and abuts the phase Pb, in Figure 6 The phase difference between the hysteresis-side outer contact phase Pbs and the hysteresis-side contact phase Pb shown indicates that the driving-side contact portion 35a and the driven-side contact portion 35b repeatedly contact and separate with a relatively short period. Figure 10 The phase angle corresponding to half (amplitude Tb) of the vibration amount Ta of the reference waveform Ts shown in the upper section is expressed as the outer contact phase Pbs of the lag angle side, which is displaced in the advance angle direction relative to the contact phase Pb of the lag angle side.

[0087] Furthermore, the relative rotation phase, which is shifted by a set phase from the lag angle side outer contact phase Pbs towards the advance angle direction, is used as... Figure 7 The hysteresis angle correction target phase Pbc is shown. Furthermore, in the hysteresis angle correction target phase Pbc, even when the driving side abutment 35a and the driven side abutment 35b are closest, a gap is formed between them.

[0088] The phrase "the driving-side contact portion 35a and the driven-side contact portion 35b are closest" is used to describe the positional relationship in which a gap is formed between the driving-side contact portion 35a and the driven-side contact portion 35b. For example, when the driving-side contact portion 35a and the driven-side contact portion 35b are displaced in a direction that approaches each other, it can also be described as the positional relationship before they are about to come into contact.

[0089] Hereinafter, the concepts of the lead angle-side contact phase Pa and the lag angle-side contact phase Pb are sometimes referred to as contact phases, and the concepts of the lead angle-side correction target phase Pac and the lag angle-side correction target phase Pbc are referred to as correction target phases. The control methods for setting the lead angle-side correction target phase Pac or the lag angle-side correction target phase Pbc are described below.

[0090] Based on such reasons, Figure 8 As shown, after detecting the contact phase (the contact phase Pa on the advance angle side and the contact phase Pb on the lag angle side) through the contact control procedure (step #200), the signal of the rotation angle detected by the rotation sensor RS in step #101 is used to calculate... Figure 5 , Figure 7 The values ​​of the corrected target phases (Pac on the lead angle side and Pbc on the lag angle side) are shown and stored in memory.

[0091] Next, the target phase for phase control is acquired (step #102). If, based on the acquired target phase (when connected), it can be determined that the target phase is not close to the drive-side contact portion 35a and the driven-side contact portion 35b, and therefore no contact occurs through the contact structure 35 (step #103, no), the phase control motor M is controlled in the direction of reducing the phase difference (deviation) between the actual phase detected by the phase sensor PS (crankshaft angle sensor 16, cam angle sensor 17) and the target phase (step #105). This phase control is performed by the phase control unit 42.

[0092] In contrast, when phase control is performed based on the acquired target phase, if it can be determined that the driving-side abutment portion 35a and the driven-side abutment portion 35b are abutting through the abutment structure 35 (as in step #103), the target phase value is replaced, and a new target phase is set (either the advance angle-side corrected target phase Pac or the lag angle-side corrected target phase Pbc) (step #104) and phase control is performed. Steps #104 and #105 are processes performed by the target phase correction unit 45.

[0093] That is, when the target phase is set at the advance angle side relative to the advance angle side outer contact phase Pas, the target phase Pac is corrected by resetting the advance angle side instead of the target phase. Even if the target phase reaches the advance angle side contact phase Pa due to the action of the cam change torque, it is possible to control the formation of a gap that prevents the drive side contact portion 35a and the driven side contact portion 35b from contacting each other.

[0094] Similarly, when the outer contact phase Pbs of the lag angle side is set to the lag angle side, the target phase Pbc of the lag angle side is reset by replacing the target phase. Even if the target phase reaches the lag angle side contact phase Pb due to the action of the cam change torque, it is possible to control the gap so that the drive side contact portion 35a and the driven side contact portion 35b do not contact.

[0095] Therefore, even if the gap between the drive-side contact portion 35a and the driven-side contact portion 35b changes due to the change torque of the cam, it prevents adverse conditions caused by their contact, and avoids the need to apply a large load to the reduction gear G, thus preventing adverse conditions that could damage the reduction gear G.

[0096] (Control method: Contact phase detection procedure)

[0097] Figure 9The contact phase detection procedure (step #200) is referred to as a sub-procedure. In this procedure, the relative rotational phase is displaced in the direction (towards the mechanical limit) in which the contact parts (driving-side contact part 35a and driven-side contact part 35b) contact each other, driven by the phase control motor M. During this drive, the angular velocity calculation unit 46 calculates and obtains waveforms representing changes in angular velocity based on the rotation sensor RS of the phase control motor M (steps #201 and #202), and determines whether contact exists by comparing the obtained waveforms (steps #203 and #204). The contact phase detection procedure in step #200 is executed by the contact phase detection unit 43.

[0098] As described above, when engine E is running, due to the effect of the cam's variable torque, the internal rotor 22 alternately moves in the advance angle direction Sa and the lag angle direction Sb for a short period of time. Figure 10 The upper section represents the waveform of the change in angular velocity when the contact parts are not in contact with each other, and is represented as a reference waveform Ts of a sine wave. In contrast, when the contact parts are in contact with each other, taking the phase at which the driving-side contact part 35a and the driven-side contact part 35b come into contact as a reference, since only the direction of separation is allowed, the waveform representing the change in angular velocity becomes... Figure 11 The upper section shows the limiting waveform Tr. Based on this reasoning, in step #203, a comparison is made with the previously acquired waveform, and the contact state and non-contact state are determined by whether the waveform changes.

[0099] Figure 11 The horizontal axis of the reference waveform Ts shown in the upper section represents the elapsed time, and the vertical axis represents the angular velocity. If the contact parts are not considered to be in contact (No in step #204), the control steps #201 and #202 are repeated. Conversely, if it is determined that the transition to a state where the contact parts are in contact (Yes in step #204), the actual phase whose phase change is limited is detected (in...). Figure 11 The phase change of the upper segment is represented as the phase of “0”, which is used as the abutment phase (the abutment phase Pa on the advance angle side and the abutment phase Pb on the lag angle side) and stored in memory in step #205.

[0100] The contact phase is due to the repeated displacement of the driving-side contact portion 35a and the driven-side contact portion 35b towards the approach and separation directions caused by the change in torque of the cam, thus representing the actual phase when they are closest to each other under the condition of repeated changes in actual phase.

[0101] Furthermore, when the contact parts reach a contact state, as described above, since the waveform acquired afterward changes relative to the waveform acquired previously, when the amount of change in the waveform exceeds a predetermined value (e.g., when the angular velocity is lower than a set value, etc.), the control mode can be set to acquire the actual phase detected by the phase sensor PS as the contact phase.

[0102] The control in steps #201 to #204 is performed on both the advance angle side and the lag angle side. Therefore, in the contact phase detection procedure, the contact phase Pa on the advance angle side and the contact phase Pb on the lag angle side are detected. This contact phase detection procedure (step #200) can be performed, for example, when the output of engine E decreases, such as when engine E shifts to idle, or it can be performed multiple times while engine E is running. Furthermore, a dedicated sensor for detecting angular velocity can also be used to achieve this control.

[0103] (Effects of the implementation method)

[0104] In the valve opening and closing period control device A, for example, when the target phase of the phase control is set to the maximum advance angle phase (advance angle side contact phase Pa), or when the target phase is set to the contact side (advance angle side) relative to the advance angle side outer contact phase Pas, the advance angle side outer contact phase Pas is set as the target phase instead of the target phase. Thus, even if the relative rotation phase changes by a predetermined amplitude and the drive side contact portion 35a and the driven side contact portion 35b are displaced in the direction of approach, a gap is formed between the drive side contact portion 35a and the driven side contact portion 35b. Therefore, damage to the reduction gear G of the drive mechanism is prevented, and the intake valve Va is opened and closed when needed.

[0105] Furthermore, since the contact phase detection procedure is performed at the specified timing of the phase control, the correct contact position can be detected and appropriate control can be achieved even if the contact phase changes due to, for example, over the years.

[0106] Furthermore, since a non-volatile memory is used, even if the contact phase detection procedure is not executed after engine E is started, the corrected target phase (the advance angle side corrected target phase Pac and the lag angle side outer contact phase Pbs) stored in the memory can still be used. In addition, since the contact phase (the advance angle side contact phase Pa and the lag angle side contact phase Pb) is stored in the memory, the corrected target phase can also be calculated based on the contact phase.

[0107] (Other implementation methods)

[0108] In addition to the embodiments described above, the present invention may also be configured as follows (the structural labels and numbers and symbols that have the same function as those in the embodiments are the same as those in the embodiments).

[0109] (a) The control in the contact phase detection procedure (step #200) is in accordance with Figure 12 The flowchart is as follows. In this other embodiment (a), it is assumed that the control method involves detecting the current supplied to the phase-controlled motor M (electric motor) by the motor control unit 47.

[0110] That is, by driving the phase control motor M, the relative rotation phase is shifted in the direction that makes the contact parts (driving side contact part 35a and driven side contact part 35b) contact each other (towards the mechanical limit), and contact control is performed to make them contact each other. The current supplied to the phase control motor M during the contact control is obtained (steps #201 and #202), and the contact state is determined based on the obtained current (step #203).

[0111] The phase-controlled motor M has a structure where the current supplied to the phase-controlled motor M increases as the load increases when the contact parts come into contact with each other. If the current does not increase in step #203, it is determined that the contact parts are not in contact with each other (No in step #203), and the control in steps #201 and #202 is repeated. Conversely, if the current supplied to the phase-controlled motor M increases, it is determined that the contact parts have reached the contact state (Yes in step #203), and the actual phase at the time of detection is stored in the memory (Step #204).

[0112] Under low load conditions where the contact parts are not in contact with each other, due to the effect of the cam's variable torque and based on the detection signal from the rotation sensor RS, the change in angular velocity is as follows: Figure 10 As shown in the basic waveform Ts at the upper end, it varies in a manner that depicts a sine wave. Thus, the current supplied to the phase-controlled motor M under low load conditions, such as... Figure 10 As shown in the current value chart Mc of the lower section, a constant current value Q1 is supplied to the phase-controlled motor M.

[0113] In contrast, when the load increases due to the contact parts (driving-side contact part 35a and driven-side contact part 35b) abutting against each other, since only the direction of separation of the contact parts is allowed, the change in angular velocity is as follows: Figure 11 As shown in the previous paragraph, the waveform is varied in the way that the limiting waveform Tr is depicted.

[0114] Thus, under conditions of increased load, such as Figure 11As shown in the current value chart Mc of the lower section, the current value increases dramatically whenever the contact parts come into contact with each other. Therefore, by setting a threshold Q2, it can be determined that the contact parts have reached a contact state when a current exceeding the threshold Q2 is measured.

[0115] In this alternative embodiment (a), the contact phase Pa on the advance angle side and the contact phase Pb on the lag angle side are also detected by performing contact phase detection procedures on both the advance angle side and the lag angle side. This alternative embodiment (a) provides simple control and allows for reliable detection of the contact phase. Furthermore, in this alternative embodiment (a), a dedicated current sensor can also be installed to achieve control.

[0116] (b) To enable control in the contact phase detection procedure (step #200), consider using a phase sensor PS that detects the relative rotation phase with high accuracy. Although Figure 1 The phase sensor PS shown is difficult to detect the relative rotation phase with high precision. However, if a phase sensor PS that detects the relative rotation phase at multiple moments when the intake camshaft 7 rotates one revolution is used, the relative rotation phase can be shifted in the direction (towards the mechanical limit) in which the contact parts (drive-side contact part 35a and driven-side contact part 35b) contact each other during the contact phase detection process. This allows for the high-precision acquisition of the actual phase at the moment when the change in relative rotation phase stops when the contact parts are in contact. Therefore, the acquired actual phase can also be stored as the contact phase.

[0117] In this other embodiment (b), the contact phase Pa on the advance angle side and the contact phase Pb on the lag angle side are also detected by performing contact phase detection procedures on the advance angle side and the lag angle side.

[0118] (c) In the control of the phase control unit 42, for example, if the contact phase is known, such as when the contact phase is already stored in the memory when the engine E is started, it is also considered that the contact phase detection procedure (step #200) is not performed, and the vibration amount of the actual phase is obtained, and the control mode is set in such a way as setting the correction target phase (advance angle side correction target phase Pac, lag angle side correction target phase Pbc) based on the vibration amount.

[0119] In this other embodiment (c), since no control is performed for detecting the contact phase, the target phase can be set quickly.

[0120] (d) The control method can also be configured such that the target phase for correction is set to either the advance angle contact phase Pa or the lag angle contact phase Pb.

[0121] Industrial utilization potential

[0122] This invention can be used in electrically operated valve opening and closing timing control devices.

[0123] Symbol Explanation

[0124] 1 crankshaft

[0125] 7. Intake camshaft (camshaft)

[0126] 21. Drive box (drive-side rotating body)

[0127] 22 Internal rotor (driven side rotating body)

[0128] 35a Drive-side contact part

[0129] 35b Driven side contact part

[0130] 42 Phase Control Unit

[0131] 45 Target Phase Correction Unit

[0132] 46 Angular velocity calculation unit

[0133] E-engine (internal combustion engine)

[0134] G reduction gear

[0135] M-phase controlled motor (electric motor)

[0136] Pac advance angle side correction target phase

[0137] Pbc hysteresis side correction target phase

[0138] RS Rotary Sensor

[0139] PS phase sensor

[0140] X Rotation axis

Claims

1. A valve opening and closing period control device, wherein, The device comprises: a drive-side rotating body that rotates freely about a rotation axis and synchronously with the crankshaft of an internal combustion engine; a driven-side rotating body that rotates freely about the rotation axis and integrally with the camshaft of the internal combustion engine for valve opening and closing; an electric motor and a reduction gear for controlling the relative rotational phase of the drive-side and driven-side rotating bodies; a phase sensor that detects the relative rotational phase as the actual phase; a phase control unit that controls the electric motor in a direction that reduces the phase difference between the actual phase and the target phase when a target phase is set; a rotation sensor that detects a signal corresponding to the rotation angle of the electric motor; and an angular velocity calculation unit that calculates the angular velocity based on the signal corresponding to the rotation angle detected by the rotation sensor. Furthermore, the valve opening and closing timing control device is configured to have an abutment phase, which is the mechanical limit of the relative rotation phase formed by the abutment of the drive-side abutment portion formed on the drive-side rotating body and the driven-side abutment portion formed on the driven-side rotating body. The relative rotation phase varies by a specified amplitude. The valve opening / closing period control device includes a target phase correction unit. This target phase correction unit replaces the target phase and sets a corrected target phase as a new target phase. This corrected target phase is a phase in which, even if the relative rotation phase changes by the predetermined amplitude, it does not reach the abutment phase when the target phase is set to the contact phase, or when the target phase is set to the phase where the relative rotation phase reaches the contact phase through a change of the predetermined amplitude, thus forming a gap between the driving-side contact portion and the driven-side contact portion. After the phase sensor detects that the relative rotation phase has reached the contact phase, the target phase correction unit sets the correction target phase based on the contact phase. The phase control unit performs contact control to make the driving-side contact part abut against the driven-side contact part. In this contact control, when representing the waveform change of the change in angular velocity obtained by the angular velocity calculation unit, the actual phase detected by the phase sensor is set as the contact phase.

2. The valve opening and closing period control device according to claim 1, wherein, The phase control unit performs contact control, which shifts the relative rotation phase by a predetermined amplitude to a phase in which the driving-side contact part contacts the driven-side contact part. In this contact control, the phase sensor detects how the actual phase changes repeatedly over time in the direction that causes the driving side contact portion to separate from the driven side contact portion and in the direction that causes the driving side contact portion to approach the driven side contact portion, with a predetermined amplitude, and sets the actual phase when the driving side contact portion and the driven side contact portion are closest as the contact phase.

3. The valve opening and closing period control device according to claim 1, wherein, It also includes a current sensor that detects the current supplied to the motor. The phase control unit performs contact control to make the driving-side contact part abut against the driven-side contact part. In this contact control, when the current detected by the current sensor increases, the actual phase detected by the phase sensor is set as the contact phase.

4. The valve opening and closing period control device according to claim 1, wherein, The target phase correction unit takes the phase obtained by adding a phase corresponding to a value greater than 1 / 2 of the variation amplitude when the relative rotation phase changes by the predetermined amplitude to the target phase as the corrected target phase.

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