JP2615158B2 - Abnormality detection device for connection switching mechanism of valve timing control device of internal combustion engine - Google Patents

Description

The present invention relates to a valve timing control device for switching the opening and closing timing of intake and exhaust valves of an internal combustion engine between a low speed valve timing and a high speed valve timing in accordance with the operating state of the engine. The present invention relates to an abnormality detection device for a connection switching mechanism.

(Prior Art) A low-speed cam and a high-speed cam having a larger lift than the low-speed cam and having a valve opening period longer than the low-speed cam are connected to the camshaft of the internal combustion engine.
First and second rocker arms slidingly contacting the low-speed cam and the high-speed cam, respectively, and a connection switching mechanism for switching between a connection state for connecting the first and second rocker arms and a state for releasing the connection state. By controlling the switching mechanism in accordance with the operation state of the engine, the first rocker arm is swung by the respective profiles of the high-speed cam and the low-speed cam in the connected state and the released state, respectively, to interlock with the first rocker arm. For example, a valve timing control device for an internal combustion engine in which an intake valve or an exhaust valve is driven at a timing corresponding to an engine operating state is disclosed in
61-19911.

In such a valve timing control device, the connection / disconnection of the first rocker arm and the second rocker arm is performed by a connection switching mechanism that operates according to hydraulic pressure.

The connection switching mechanism includes, for example, a guide hole provided in each arm such that the first and second rocker arms are aligned with each other when the first and second rocker arms are on the base circles of the low-speed cam and the high-speed cam, respectively.
A switching pin that slides in the two guide holes, and slides the switching pin by applying hydraulic pressure to one end surface of the switching pin. Then, when the switching pin is located across both guide holes, the first and second rocker arms are integrally connected to obtain a timing (high-speed valve timing) corresponding to the high-speed cam, while the switching pin is in contact with the high-speed cam. When only one of the guide holes is in the guide hole, the connected state of the first and second rocker arms is released, and the respective rocker arms can obtain a timing (low-speed valve timing) corresponding to the low-speed cam independently of each other. The hydraulic pressure applied to the switching pin of the connection switching mechanism is controlled based on a command signal from an electronic control unit in the valve timing control device according to the engine operating state.

(Problems to be Solved by the Invention) However, when the valve timing control device is actually operated, the content of the command signal from the electronic control unit does not match the connection state between the first and second rocker arms. In other words, the intake / exhaust valves are operating at low valve timing even though the electronic control unit is instructing high speed valve timing control due to the switching pin getting stuck in the guide hole, etc. An abnormal state may occur in which the control is instructed to operate at a high-speed valve timing despite being instructed. If no measures are taken at the time of occurrence of this abnormal condition, other control of the engine (fuel control, ignition timing control, etc.) performed in connection with the valve timing control and the control contents of the valve timing control do not match, and the engine operability is not improved. This will result in a decline.

(Object of the Invention) The present invention has been made in order to achieve the above object, and the valve timing control device constantly monitors the operating state of the intake / exhaust valve and performs valve timing control in accordance with an instruction from the control device. An object of the present invention is to provide an abnormality detection device for a connection switching mechanism of a valve timing control device for an internal combustion engine, which can detect whether or not the operation is actually performed.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a low-speed cam and a high-speed cam connected to a camshaft of an internal combustion engine, and a low-speed cam and a high-speed cam slidingly contacting the low-speed cam and the high-speed cam, respectively. 1st and 2nd
A rocker arm, and a connection switching mechanism for switching between a connection state for connecting the first and second rocker arms and a state for releasing the connection state, wherein the first rocker arm is connected to the high-speed cam in the connection state and in the release state, respectively. And a first and second rocker arm and the camshaft, wherein the first and second rocker arms are slid by respective profiles of a low-speed cam to drive an intake valve or an exhaust valve interlocked with the first rocker arm. A power supply for applying a voltage to a circuit composed of the first and second circuits;
A value corresponding to a resistance value between the rocker arm and the camshaft is detected, and the first and second values are determined according to the detected value.
A connection state detecting means for detecting a connection state between the rocker arms, and an abnormality determination means for determining whether or not the connection switching mechanism is abnormal based on an output from the connection state detection means.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an essential part for explaining a valve operating mechanism of a DOHC type multi-cylinder (four cylinder) internal combustion engine to which a valve timing control device according to the present invention is applied. In the figure, reference numeral 1 denotes a cylinder block of an engine. Four cylinders 2 (only one cylinder is shown) 2 are provided in the cylinder block 1 in series. A combustion chamber 5 is defined between a cylinder head 3 coupled to the upper end of the cylinder block 1 and a piston 4 slidably fitted to each cylinder 2. Further, each combustion chamber 5 is provided in the cylinder head 3.
A pair of intake ports 6 and a pair of exhaust ports 7 are respectively attached to portions forming a ceiling surface of the cylinder head. Each of the intake ports 6 is connected to an intake port 8 opened on one side surface of the cylinder head 6, and each of the exhaust ports 7 Is connected to an exhaust port 9 opened on the other side surface of the cylinder head 3.

In order to guide a pair of intake valves 10i capable of opening and closing each intake port 6 and a pair of exhaust valves 10e capable of opening and closing each exhaust port 7, a portion corresponding to each cylinder 2 of the cylinder head 3 is guided.
The guide cylinders 11i and 11e are fitted and fixed respectively, and the intake valves 10i protruding upward from the guide cylinders 11i and 11e.
And a flange 12 attached to the upper end of each exhaust valve 10e.
Valve springs 13i, 13e are respectively contracted between i, 12e and the cylinder head 3, and the intake valves 10i and the exhaust valves 10e are attached upward, that is, in the valve closing direction by the valve springs 13i, 13e. Be inspired.

A working chamber 15 is defined between the cylinder head 3 and a head cover 14 connected to the upper end of the cylinder head 3, and an intake valve for each cylinder 2 is provided in the working chamber 15.
An intake valve side valve device 17i for opening and closing the 10i and an exhaust valve side valve device 17e for opening and closing the exhaust valve 10e in each cylinder 2 are housed and arranged.

These dual valve devices 17i and 17e open the intake valve 10i and the exhaust valve 10e in accordance with the rotation of the camshafts 18i and 18e which are driven to rotate at a speed ratio of 1/2 from the crankshaft (not shown) of the engine.・ It is designed to close.

The camshafts 18i and 18e are arranged in parallel to the arrangement direction of the cylinders, and are rotatably supported by a camshaft support (not shown). Timing pulleys 27 and 28 are fixed to one end of the shafts 18i and 18e protruding from the cylinder head 3 and the head cover 14, and a timing belt 29 for transmitting a driving force from a crankshaft (not shown).
Is wound around both timing pulleys 27 and 28. As a result, both camshafts 18i and 18e rotate in the same direction as the crankshaft rotates.

Next, the second basic configuration of the intake valve-side valve train 17i will be described.
This will be described with reference to FIGS. Note that the exhaust valve side valve gear 17e basically has the same configuration as the intake valve side valve gear 17i, and in the following description, the exhaust valve side valve gear 17e The same reference numerals with the suffix i are used to add the suffix e to the drawings, and the description is omitted. In addition, since the intake valve side valve gear 17i has the same structure for all cylinders, only one cylinder (# 1 cylinder) will be illustrated and described.

The intake valve-side valve train 17i is provided with a low-speed cam 19i, 20i and a high-speed cam 21i provided on a camshaft 18i for each cylinder.
(Only one cylinder is shown in FIG. 2), a rocker shaft 22i fixed and arranged in parallel with the camshaft 18i as shown in FIGS. 1 and 3, and a rocker corresponding to each cylinder 2. Drive rocker arm 2 pivotally supported by shaft 22i
3i, drive rocker arm 24i (above, first rocker arm) and free rocker arm 25i (second rocker arm)
And the corresponding cam 19 of the rocker arm 23i, 24i, 25i.
i, 20i, and 21i, cam slippers 60, 61, and 62 as resistance members disposed on sliding surfaces, and rocker arms 23i, 24i, and 25i.
And a connection switching mechanism 26i provided for each cylinder to perform connection / disconnection between the cylinders. The rocker shaft 22i is located below the camshaft 18i in FIG. 1 and has an axis parallel to the camshaft 18i and is fixedly held by a rocker shaft support (not shown).
As shown in FIGS. 2 and 3, the rocker shaft 22i has a drive rocker arm 23i linked and connected to one intake valve 10i, and a drive rocker arm 24i linked and linked to the other intake valve 10i. A free rocker arm 25i disposed between both drive rocker arms 23i, 24i is pivotally supported adjacent to each other (FIGS. 2 and 3).

Tappet screws 30i are screwed to the drive rocker arms 23i and 24i so as to be able to advance and retreat, respectively.
30i abuts on the upper end of the corresponding intake valve 10i, whereby both drive rocker arms 23i, 24i are respectively linked with the intake valve 10i,
Be linked.

The free rocker arm 25i is elastically urged by a lost motion mechanism 31i interposed between the free rocker arm 25i and the cylinder head 3 shown in FIGS. The lost motion mechanism 31i has a bottomed cylindrical guide member 32 fitted to the cylinder head 3 with the closed end facing the cylinder head 3, a slidably fitted to the guide member 32 and a free rocker arm 25i. And a spring 34 interposed between the piston 33 and the guide member 32 to bias the piston 33 toward the free rocker arm 25i.

Next, drive rocker arms 23i and 24i and free rocker arm 2
The connection switching mechanism 26i formed in 5i will be described with reference to FIGS.

The connection switching mechanism 26i includes a first switching pin 35 capable of connecting the drive rocker arm 23i and the free rocker arm 25i, a second switching pin 36 capable of connecting the free rocker arm 25i and the drive rocker arm 24i, and first and second switching. It has a regulating pin 37 for regulating the movement of the pins 35 and 36, and a return spring 38 for urging the pins 35 to 37 toward the uncoupling side.

The drive rocker arm 23i has a bottomed first guide hole 39 opened to the free rocker arm 25i side in parallel with the rocker shaft 22i.
35 is slidably fitted, and a hydraulic chamber 40 is defined between one end of the first switching pin 35 and the closed end of the guide hole 39. Moreover, a passage 41 communicating with the hydraulic chamber 40 is formed in the drive rocker arm 23i, an oil supply passage 42i is provided in the rocker shaft 22i, and the oil supply passage 42i is provided through the passage 41 regardless of the swinging state of the drive rocker arm 23i. To communicate with the hydraulic chamber 40 at all times.

A guide hole 43 corresponding to the guide hole 39 is formed in the free rocker arm 25i in parallel with the rocker shaft 22i between both side surfaces, and a second switch pin having one end contacting the other end of the first switching pin 35. The switching pin 36 is slidably fitted in the guide hole 43.

A guide hole 44 having a bottom corresponding to the guide hole 43 is opened in the drive rocker arm 24i on the free rocker arm 25i side and is formed in parallel with the rocker shaft 22i. The disc-shaped regulating pin 37 in contact is slidably fitted in the guide hole 44. In addition, a guide cylinder 45 is fitted to the closed end of the guide hole 44, and a shaft portion 46 slidably fitted in the guide cylinder 45 is coaxially and integrally formed with the regulating pin 37. The return spring 38 is provided with a guide cylinder 45 and a regulating pin.
The return spring 38 inserts each pin 3
5, 36, 37 are urged toward the hydraulic chamber 40 side.

In this connection switching mechanism 26i, all the rocker arms 23
When i, 24i, 25i are in contact with the respective cams 19i, 20i, 21i on the base circle, all the guide holes 39, 43, 44 are aligned, so that the hydraulic pressure in the hydraulic chamber 40 is increased during the alignment, The first switching pin 35 is fitted into the guide hole 43 and the second switching pin 36 is
The rocker arms 23i, 25i, and 24i are connected to each other by fitting to the lock 44. When the oil pressure in the hydraulic chamber 40 decreases, the first switching pin 35 returns to a position where the contact surface of the first switching pin 35 and the second switching pin 36 corresponds between the first drive rocker arm 23i and the free rocker arm 25i by the spring force of the return spring 38. , The second switching pin 36 is a regulating pin
Since the contact surface with 37 returns to the position corresponding to the position between the free rocker arm 25i and the second drive rocker arm 24i, the connected state of each rocker arm 23i, 25i, 24i is released.

The rocker shaft 22i is connected to a battery 47, which is a power source of a connection state detecting means (pin lock sensor 103) described later, and a predetermined voltage is applied to the rocker arm 23i and other adjacent rocker arms 24i and 25i. It has become. The rocker arms 23i, 24i, 25i and the rocker shaft 22i are electrically insulated from other components of the vehicle (engine body, body, etc.). on the other hand,
The camshaft 18i is electrically connected to an electronic control unit 100 to be described later via a combined resistance value detecting means 103a of the pin lock sensor 103 as described in detail below. The camshaft 18i may be electrically insulated from other components of the vehicle, and the rocker shaft 22i may be used as the detection side.

Next, a hydraulic control device for supplying oil to the hydraulic chamber 40 of the connection switching mechanism 26i will be described with reference to FIG. An oil gallery 53 is connected to a discharge port of an oil pump 49 that pumps oil from an oil pan 48 via a relief valve 50, an oil filter 51, and an oil cooler 52, and hydraulic pressure is transmitted from the oil gallery 53 to each connection switching mechanism 26i. Is supplied, and lubricating oil is supplied to each lubricating portion of the valve train 17i.

The oil gallery 53 has a filter 55
A switching body 54 for switching the hydraulic pressure that has passed through between high and low to supply the oil is connected to the oil supply passage 4 in the rocker shaft 22i.
2i is connected to the oil gallery 53 via the switching valve 54. The switching valve 54 is connected to a pipe 54a through which a part of the oil to the oil supply path 42i flows.
An electromagnetic solenoid 56 is arranged in the middle of 4a. The solenoid valve 56 is connected to an electronic control unit (hereinafter referred to as “ECU”).
The line 54a is cut off / communicated based on a drive signal (command signal) from the controller 100. By switching on / off the solenoid valve 56, the switching valve 54 is moved to a position where the throttle valve operates without a throttle and a throttle. Is switched to a position communicating with the
The oil pressure in the oil supply passage 42i is switched between high pressure and low pressure.

A high-speed lubricating passage 57i as a lubricating oil passage communicates with the oil supply passage 42i via a throttle A, while an oil passage 58 branched from the oil gallery 53 on the upstream side of the filter 55. Is connected to a low-speed lubrication path 59i via a throttle B. These lubricating passages 57i, 59i extend above and in parallel with the camshaft 18i, and lubricating oil is injected from each ejection port of the lubricating passages 57i, 59i toward each part of the valve gear. .

The ECU 100 includes an engine speed (hereinafter referred to as a “Ne sensor”).
) 101 and a cylinder discrimination sensor (hereinafter referred to as “CYL sensor”) 102 are electrically connected. These sensors 10
1, 102 are mounted around the engine camshaft 18 or around a crankshaft (not shown), the former 101 is a TDC signal, that is, a predetermined crank angle position every 90 ° rotation of the engine camshaft, and the latter 102 is a predetermined crank angle position of a specific cylinder. One pulse is output at each angular position, that is, every 360 ° rotation of the camshaft, and these pulses are supplied to the ECU 100.

Further, another parameter sensor 104 such as an engine water temperature sensor is electrically connected to the ECU 100, and a detection signal of the sensor 104 is supplied to the EUC 100. Further, an output terminal of a pin lock sensor 103, which will be described in detail later, is connected to the ECU 100, and the low-speed and high-speed cams 19 from the sensor 103 are connected thereto.
i, 20i, 21i and cam slippers 60, 61, 6 respectively corresponding to the cams.
An output signal indicating the state of connection to the ECU 2 is supplied to the ECU 100.

Further, the ECU 100 is connected to a fail-safe mechanism 110 that performs a predetermined fail-safe operation (abnormal warning, abnormal display, etc.) when detecting a pin lock state.

The ECU 100 has an input circuit having functions of shaping input signal waveforms from the above-described various sensors, correcting a voltage level to a predetermined level, and converting an analog signal value to a digital signal value.
100a, central processing circuit (hereinafter referred to as "CPU") 100b, CP
The U100b includes a storage means 100c for storing a control program, a calculation result, and the like shown in FIG. 14, which will be described later, and an output circuit 100d for supplying drive signals to the solenoid valve 56 and the fail-safe mechanism 110, respectively.

Next, the basic operation of the intake valve side drive device 17i according to the command signal of the EUC 100 will be described with reference to FIGS. 2 to 5 again.

First, ECU100 is the various engine parameter sensors described above.
An engine operating state is determined based on signals from 101 to 104, and it is determined whether the engine is in an operating state in which high-speed valve timing control is to be performed or in an operating state in which low-speed valve timing control is to be performed.

The ECU 100 generates a drive signal to the solenoid valve 56, that is, a command signal to the valve train 17i, based on the determination result.

Now, suppose that the content of the command signal of the ECU 100 commands the low-speed valve timing state. At this time the magnetic valve
The valve 56 is closed, and the oil pressure supplied into the oil supply passage 42i via the switching valve 54 decreases. When the oil pressure in the hydraulic chamber 40 of the connection switching mechanism 26i falls below the pressing force of the return spring 38 due to the decrease in the oil pressure, the pins 35, 36,
37 moves downward in FIG. 5 to move the rocker arms 23i, 24i, 25
The operations of i become independent from each other (the state of FIG. 4). When the camshaft 18i rotates in this state, the drive rocker arms 23i and 24i move up and down along the profile of the low speed cams 19i and 20i shown in FIG.
Moves up and down along the profile of the high-speed cam 21i also shown in FIG. Therefore, when the low-speed valve timing control is being performed, each rocker arm 23i, 24i, 25i has a corresponding cam 19i, 20i, 21i and cam slipper 60, 61, 62, respectively.
Are always in sliding contact with each other.

On the other hand, when the content of the command signal of the ECU 100 indicates a high-speed valve timing state, the solenoid valve 46 is opened, and the oil pressure in the oil supply passage 42i via the switching valve 54 increases.
When the oil pressure in the hydraulic chamber 40 of the connection switching mechanism 26i becomes larger than the pressing force of the return spring 38 due to the increase of the oil pressure, the spring 38
The above-mentioned pins 35, 36, 37 move upward in FIG. 4 against the pressing force of FIG. 4 to connect the rocker arms 23i, 24i, 25i to each other, and their operations are integrated (the state of FIG. 5). ). When the camshaft 18i rotates in this state, the free rocker arm 2
5i moves up and down along the profile of the high-speed cam 21i (FIG. 7) as in the low-speed valve timing control, but the drive rocker arms 23i and 24i are free irrespective of the profile of the low-speed cams 19i and 20i. It moves up and down integrally with the rocker arm 25i. Therefore, when in the high-speed valve timing state, the free rocker arm 25i is
2, the driving rocker arms 23i and 24i are in sliding contact with the low speed cams 19i and 20i and the high speed cam 21i.
Only in the rotation angle of the camshaft 18i (i.e., the angle range shown in FIG. 7X, that is, the range in which both the cams 19i and 20i are in the base circle) the profile of i coincides with the low-speed cams 19i and 20i. Rotation angle (angle range shown in FIG. 7Y)
Then, as shown in FIG. 2 (c), the drive rocker arms 23i, 24
i and the cam slippers 60 and 61 are separated.

Connection state detecting means (pin lock sensor 10) according to the present invention
3) Each such cam 19i, 20i, 21i and each rocker arm 23i, 24
This focuses on the connection state with i, 25i.

That is, the pin lock sensor 103 regards the low-speed cams 19i, 20i and the cam slippers 60, 61 as switching members, and connects (ON) / disconnects (connects) the cams 19i, 20i and the cam slippers 60, 61. OFF) state is detected electrically.

More specifically, as shown in FIGS. 2 and 3, the pin lock sensor 103 includes a battery 47 for applying a predetermined voltage to each rocker arm 23i, 24i, 25i, and a drive rocker arm 23i, 24.
i, the cam slippers 60 and 61 having a predetermined resistance value (the combined resistance values of the cam slippers 60 and 61 can be set to a first predetermined resistance value R _L1 ), and a second predetermined value disposed on the free rocker arm 25i. Cam slipper 6 with resistance value R _M1 (R _M1 >> R _LD )
2, and a combined resistance detecting means 103a connected to a camshaft 18i in which each of the cams 19i, 20i, 21i is integrally formed.

It should be noted that only one pin lock sensor 103 is provided for each of the intake valve side valve operating device 17i and the exhaust valve side valve operating device 17e. Therefore, the pin lock sensor 103 is used for a four-cylinder internal combustion engine. Have respective circuit configurations as shown in FIG.

In FIG. 8, R _{L1 to} R _L4 indicate the combined resistance values of the cam slippers 60 and 61 on the drive lock arm side of each cylinder, and R _{M1 to} R _{M4
(R M i >> R L i} ) denotes the resistance value of the cam slipper 62 of the free rocker arm side of each cylinder.

The switch S ₁ to S ₄ is a switch imaginary to represent each low-speed cam 19i, 20i and the drive rocker arm 23i, a connection state between 24i.

Note that the resistor R ₁ and the capacitor C _{1 of} the combined resistance value detecting means 103 a
Constitutes a filter circuit for smoothing a sharp voltage change occurring at the point Z in the figure at the time of switching.

Next, a pin lock sensor 10 according to the operation of the above-described valve timing control device applied to a four-cylinder internal combustion engine.
The change of the output voltage (Z point voltage in FIG. 8) from 3 will be described.

When the valve timing control device is controlling at low speed valve timing, as described above,
19i, 20i are always driving rocker arm 23i, the switch S ₁ to S ₄ of Figure 8 since the contact 24i sliding is closed at all times (Note that high-speed cam 21i is which of the low-speed / high-speed valve timing control Even if it is selected, switching is not performed because it is always connected to the free rocker arm 25i). Therefore, the voltage V _D of the combined resistance value of Z point becomes the minimum value at this time is the maximum value V _DMAX (values indicated by the broken line in FIG. 13).

On the other hand, at the time of high speed valve timing condition opening and closing of the switch (S ₁ ~S ₄₎ in accordance with the rotation angle of the crankshaft as described above is performed.

First, opening the switch (S ₁ ) of the specific cylinder (# 1 cylinder)
Consider only the closing timing. Switch S ₁ in an angular range X of Figure 7 during the high-speed valve timing control as described above is
It turns on and turns off in the angle range Y. This is because the lift amount of the high-speed cam and the low speed cam in an angular range Y as shown in FIG. 9 differs, therefore the switch S ₁ is repeated ON / OFF at the timing of Fig. 12 (a).

Incidentally, in the case of a four-cylinder internal combustion engine, the phase of the cam profile of each cylinder shifts every time the rotation angle θ of the camshaft changes by 90 ° as shown in FIG.

As a result, the rotation angle range in which the lift amounts of the high-speed cam and the low-speed cam of each cylinder are different from each other is shifted by 90 ° by the rotation angle of the camshaft as shown in FIG. 11, and the adjacent cylinders (for example, # 1 and # 3) There is an overlapping area between the cylinders. Accordingly ON / OFF timings of the switches S ₁ to S ₄ (12
Figure (a) ~ the combined resistance value of the Figure 8 by _{R L1 ~R L4, R M1 ~R} M4 by (d)) is, although Two ON, two of S ₁ to S ₄
One and OFF region (K in Figure 12) are three in ON but becomes a value different de a region of OFF (L in Figure 12), the voltage value V _D at the point Z Figure 8 this time is 13 It changes at the timing shown by the solid line in the figure.

By the way, when the content of the command signal from the ECU 100 of the valve timing control device is switched from high-speed valve timing control to low-speed valve timing control or vice versa, the above-described switching valve
By the operation of 54, the connection switching mechanism 26i operates. During normal operation of the mechanism 26i Therefore, the output signal of the pin lock sensor 103 in accordance with a change in the content of the command signal (V _D value) of the first
3 changes from the solid line to the broken line or vice versa.

However, the connection switching mechanism 26i has an abnormality, such as being caught by the guide hole of each pin, and the pins 35, 3 in the mechanism 26i
When the locks 6 and 37 are in the locked state, the high-speed valve timing control can actually continue even though the command content of the ECU 100 is switched from the high-speed valve timing control to the low-speed valve timing control, for example. Conversely, even when the content of the command is switched from the low speed valve timing control to the high speed valve timing control, the low speed valve timing control is actually continued.

Therefore, the abnormality detection device of the connection switching mechanism of this embodiment is EC
Contents of command signal from U100 and pin lock sensor described above
The actual operation state of the rocker arm (sliding state of the cam and the rocker arm) detected by 103 is compared to detect an abnormality of the connection switching mechanism 26i.

More specifically, the operation of the abnormality detection device is performed by the ECU 100
There is achieved by executing the program shown in FIG. 14 on the basis of the content of the output signal V _D and the command signal of the pin lock sensor 103.

First, when a TDC signal is input, a new discrimination value _CYL is obtained by adding 1 to the cylinder discrimination value _CYL in step 201. For each the determination value C _YL CYL signal generated by executing the program of FIG. 15 0
Is reset to C every time the TDC signal is generated.
_YL = 1, 2, 3, 4, (0), 1, 2 ... are repeated. Therefore, by reading the value of the cylinder discriminating value _CYL , it is possible to detect which of the cylinders # 1 to # 4 has started the valve opening operation at the time of the TDC signal generation (FIG. 10). TDC
(# 1 to # 4)).

Reads the value of the output signal V _D from the pin lock sensor 103 described above In the next step 202, V _D value read said it is determined whether or not larger than the reference determination value V _LVL (Step 20
3). This is the output signal of the pin lock sensor 103 as described above. V _D value at the time of low-speed valve timing at the time of high-speed valve timing is the value shown by the broken line in FIG. 13 in which changes as indicated by a solid line in FIG. Incidentally, the timing of generation of TDC signal pulses is the start time of the program is in the region K as indicated by the arrow in FIG. 13, reading of V _D value of the step 202 is also performed within the region K You.

Therefore, the answer to step 203 is affirmative (Yes) when the intake valve is actually opened / closed by the low speed cam, and negative (No) when the intake valve is opened / closed by the high speed cam, and the process proceeds to steps 204 and 205, respectively.

In step 204, it is determined whether or not the command signal from the ECU 100 to the solenoid valve 56 indicates that the hydraulic pressure in the oil supply passage 42i in FIG. Lower the oil pressure of the low-speed valve timing control (low
V / T) is determined. Both step 203 and step 204 are affirmative (Yes)
In other words, the content of the command signal to the solenoid valve 56 and the drive rocker arms 23i, 24i detected by the pin lock sensor 103
The cam 19i, the coupling switching mechanism 26i is present is reset to 0 the value of the abnormality processing delay counter C _FS at step 206 it is determined to be operating normally program when the connection state between 20i matches To end.

On the other hand, if the answer to step 204 is negative (No), that is, if the command content to the switching valve 54 does not match the connection state between the drive rocker arms 23i and 24i and the cams 19i and 20i detected by the pin lock sensor 103, Each pin 3 in the connection switching mechanism
It is determined that an abnormal state such as a pin lock state has occurred in the guide hole in the rocker arm, etc., but the time delay from the generation of the command signal of the ECU 100 to the start of movement of each of the pins 35, 36, 37 is determined. In consideration of the case where the pins 35, 36, and 37 do not move at one time, the value of the counter _CFS is incremented by 1 in order to delay the execution of the later-described fail-safe processing until the pins 35, 36, and 37 have completely moved (step 207). ), Its count value C _FS
Has reached the predetermined value C _FSD (step 20).
8) Go to step 209 to execute the fail-safe process.

As an example of the specific processing of the fail-safe processing,
First, when it is determined that the TDC is abnormal for the first time at the present TDC at the time of the high-speed V / T command, it is determined whether or not the TDC corresponds to which cylinder, that is, the intake valve of any cylinder should start the valve opening operation. It is determined whether or not there is. For example, assuming that the TDC corresponds to the # 1 cylinder this time, the camshaft 18i rotates as indicated by the arrow in FIG. 10, so if the time when the previous TDC (# 2) occurred is normal, the # 2 cylinder It is considered that the intake valve has already started the normal valve opening operation. Therefore, the abnormality at the time of occurrence of the TDC (# 1) this time is determined to be due to the abnormality of the opening operation of the intake valve of the # 1 cylinder. At this time, the ECU 100 performs a fail-safe operation such as notifying the driver of the cylinder in which the abnormality has occurred by LED display or the like by the above-described fail-safe mechanism 110.
Further, in the fail-safe processing, it is possible to determine which operation of the high-speed / low-speed valve timing cannot be executed due to the abnormality by reading the content of the command signal of the ECU 100.

On the other hand, in step 205 executed when the answer to step 203 is negative (No), an output signal from the ECU 100 to the solenoid valve 56 outputs an instruction to control the oil pressure in the oil supply passage 42i to the high pressure side in FIG. Or not, that is, by increasing the hydraulic pressure in the hydraulic chamber 40 of the connection switching mechanism 26i to increase the high-speed valve timing (high
V / T) is determined. When the answer to step 205 is affirmative (Yes), that is, the content of the output signal to the solenoid valve 56 matches the connection state between the drive rocker arms 23i, 24i and the cams 19i, 20i detected by the pin lock sensor 103. If so, it is determined that the connection switching mechanism is operating normally, and the program ends through step 206 described above.

On the other hand, if the answer to step 205 is negative (No), that is, if the command content to the solenoid valve 56 does not match the connection state between the drive lock arms 23i, 24i and the cams 19i, 20i detected by the pin lock sensor 103, Each pin 3 in the connection switching mechanism 26i
5,36,37 it is judged that an abnormality such as in the locked state has occurred executing the steps 207 and 208, the counter value C _FS executes the fail-safe processing proceeds step 209 in the case of more than the predetermined value C _FSD Then, the program ends.

FIG. 16 is a diagram for explaining a mounting structure of the cam slippers 60, 61, and 62 used as resistance members of the connection state detecting means (pin lock sensor 103) to the rocker arms 23i, 24i, and 25i in the embodiment of the present invention. (Only the free rocker arm 25i is shown).

The drive rocker arms 23i and 24i are formed entirely of cast iron or sintered pearlitic steel, including the tip-shaped cam slippers 60 and 61.
25i side all or at least its cam slipper 62,
It is made of cast iron or sintered austenitic steel having a different electrical resistivity from the pearlite-based steel. These cam slippers 60, 61, and 62 are
It is fixed to i, 24i, 25i by brazing or the like. As a result, when the connection state between the drive rocker arms 23i, 24i and the low-speed cams 19i, 20i changes, the variation width of the combined resistance value increases, and the detection accuracy of the connection state detection means (103a) is improved. .

Incidentally, the resistance value of the steel of the cam slipper 62 (R _M ) is remarkably larger than the resistance value of the steel of the cam slippers 60 and 61, that is, the combined resistance value (R _L ) when the slippers 60 and 61 are connected in parallel. When set to be larger, the difference from the voltage V _DMAX voltage V _D at the time of OFF of the switch S ₁ to S ₄ is increased, preferably it is easy to detect the connected state by the connecting state detection means.

FIG. 17 shows that the cam slipper 62 is formed of ceramics in order to make only the resistance value (R _M ) of the cam slipper 62 infinite, and the rocker arm 25i made of steel or sintered is used.
9 shows a modification example in which the fixing member is fixed to the substrate by brazing or an adhesive. When the free rocker arm 25i is made of an aluminum alloy or cast iron, the cam slipper 62 made of ceramics may be used as a cast-in.

In this embodiment, the resistance member of the connection state detecting means (pin lock sensor 103) is fixed to the rocker arms 23i, 24i, 25i. However, for example, as shown in FIG. Even if the resistance value (R _M ) between the free rocker arm 25i and the cam 21i is infinite, the same effect can be obtained.

As shown in FIG. 19, the high-speed cam 21i itself may be formed of ceramics and fixed to the camshaft 18i by brazing. At this time, low speed cams 19i and 20i
The material itself may be made of a sintered metal and fixed by brazing or liquid phase bonding.

In this embodiment, the description has been given only of the case where the connection state detecting means and the abnormality detection method of the connection switching mechanism are applied to the intake valve side valve operating device 17i. Naturally, it can be applied to the device 17e.

Further, in this embodiment larger than the resistance value R _M combined resistance value R _L has been described as (infinity is desired), the difference is determined between the voltage value V _D and the maximum value V _DMAX of Z points during TDC signal generator It is good if it is possible, and even if both resistance values R _M and R _L are the same, R _M <R
_{It can be L.}

Further, in this embodiment, the combined resistance values R _{L1 to} R _L4 have been described as being the same value for all cylinders, but the resistance values R _{L1 to} R _L4 for each cylinder are set to different values (for example, 1, 2, 4, 8 times). by, by utilizing the fact that the voltage value V _D of the Z point is changed, and has a abnormality determination of whether or not the value of the predetermined voltage width of the voltage value V _D is provided for each cylinder The occurrence of abnormality can be determined more accurately by specifying the cylinder.

Further, in this embodiment, an abnormal display or the like is described as the fail-safe processing. However, the present invention is not limited to this. Correlation engine control devices such as an ignition timing control device, a fuel supply amount control device, and a supercharging pressure control The device may be subjected to fail-safe control based on emission characteristics, engine strength, driving performance, and the like.

(Effects of the Invention) As described in detail above, according to the present invention, a low-speed cam and a high-speed cam connected to a camshaft of an internal combustion engine,
A first and a second rocker arm slidingly contacting the low-speed cam and the high-speed cam, respectively; and a connection switching mechanism for switching between a connection state for connecting the first and second rocker arms and a state for releasing the connection state. A valve for an internal combustion engine in which the first rocker arm is swung by the respective profiles of the high-speed cam and the low-speed cam in the connected state and the released state to drive an intake valve or an exhaust valve interlocked with the first rocker arm. In the timing control device, a power supply for applying a voltage to a circuit constituted by the first and second rocker arms and the camshaft, and a resistance value between the first and second rocker arms and the camshaft are provided. Connection state detecting means for detecting a connection state between the first and second rocker arms in accordance with the detected value. Abnormality detecting means for determining whether or not the connection switching mechanism is abnormal based on the output from the state detection means, so that the operation of the connection switching mechanism can be constantly monitored with a simple configuration, When the mechanism is locked due to mechanical factors and valve timing control cannot be performed in accordance with the engine operating state, it can be quickly determined that an abnormality has occurred. As a result, a predetermined fail-safe operation can be performed, and adverse effects on other engine controls can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an essential part for explaining a valve operating mechanism of an internal combustion engine to which a valve timing control device according to the present invention is applied, and FIG. 2 is a connection switching mechanism to which an abnormality detecting device according to the present invention is applied. FIG. 3 is a side view illustrating a connection state between the low-speed cam and the high-speed cam and the drive rocker arm and the free rocker arm. FIG. 3 is a plan view illustrating an arrangement relationship between the drive rocker arm and the free rocker arm of the connection switching mechanism. 4
FIG. 5 is a cross-sectional view of the connection switching mechanism in which the drive rocker arm and the free rocker arm are connected, FIG. 5 is a cross-sectional view of the connection switching mechanism in which the drive rocker arm and the free rocker arm are released, and FIG. 6 is FIG. 5 is an overall configuration diagram of a hydraulic control device for supplying oil to a hydraulic chamber of the connection switching mechanism shown in FIG. 5, and FIG. 7 is a diagram showing a cam profile of a low speed cam and a high speed cam of a first cylinder from an axial direction of a cam shaft. FIG. 8 is a circuit diagram for explaining the configuration of the connection state detecting means (pin lock sensor) according to the present invention, and FIG. 9 is a diagram showing the low-speed cam and the high-speed cam shown in FIG. FIG. 10 is a timing chart showing the lift amounts of the drive rocker arm and the free rocker arm according to the cam profile. FIG. 10 shows the respective cam profiles of the low speed cam and the high speed cam of the first to fourth cylinders. FIG. 11 is a side view similar to FIG. 7, FIG. 11 is a timing chart showing lift amounts of the rocker arms of the cylinders according to the respective cam profiles of the low-speed and high-speed cams of each cylinder shown in FIG. 10, and FIG. a timing chart showing an eighth switch S ₁ to S ₄ of the on / off timing of the diagram according to a tenth cam profile of the FIG. 13 outputs the connection state detecting means changes in accordance with the cam Prof Eel of Figure 10 timing chart showing waveforms of signals V _D, Fig. 14 connecting program flow chart showing the abnormality judgment method by the abnormality detecting device of a switching mechanism, a program flow chart for FIG. 15 to reset the cylinder discrimination value C _YL of the present invention, FIG. 16 is a view for explaining a mounting structure of a cam slipper to a rocker arm according to an embodiment of the present invention, and FIG. 17 shows a modification in which the cam slipper is formed of ceramic. , 18th
The figure shows a modification in which a ceramic layer is formed on the cam profile surface of the high-speed cam, and FIG. 19 shows the modification in which the high-speed cam itself is formed of ceramic. 1 ... cylinder, 3 ... cylinder head, 6 ... intake port, 7 ... exhaust port, 10i ... intake valve, 11i ... exhaust valve, 17
i: Inlet valve side valve gear, 17e ...: Exhaust valve side valve gear, 18
i, 18e …… Camshaft, 19i, 20i …… Low speed cam, 21i
…… High-speed cam, 22i …… Rocker shaft, 23i, 24i ……
Drive rocker arm, 25i …… Free rocker arm, 26i ……
Connection switching mechanism, 40 hydraulic chamber, 47 battery, 54
Switching valve, 56 ... Solenoid valve, 60, 61, 62 ... Cam slipper, 10
0 ... Electronic control unit (ECU), 103 ... Connection state detection means (pin lock sensor), 103a ... Synthesis resistance value detection means, 110 ... Fail safe mechanism.

Claims (1)

(57) [Claims] 1. A low-speed cam and a high-speed cam connected to a camshaft of an internal combustion engine, first and second rocker arms slidably contacting the low-speed cam and the high-speed cam, respectively, and the first and second rocker arms. A connection switching mechanism for switching between a connection state for connecting the two and a state for releasing the connection state, wherein the first rocker arm is slid by the respective profiles of the high-speed cam and the low-speed cam in the connection state and the release state, respectively. In the valve timing control device for an internal combustion engine configured to drive an intake valve or an exhaust valve interlocked with the first rocker arm, a voltage is applied to a circuit including the first and second rocker arms and the camshaft. A power supply and a value corresponding to a resistance value between the first and second rocker arms and the camshaft are detected, and a previous value is determined according to the detected value. A connection state detection unit that detects a connection state between the first and second rocker arms; and an abnormality determination unit that determines whether the connection switching mechanism is abnormal based on an output from the connection state detection unit. An abnormality detection device for a connection switching mechanism of a valve timing control device for an internal combustion engine.