JP3678583B2 - Engine crank angle position detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crank angle position detecting device in an engine having a variable valve operating device.
[0002]
[Prior art]
Conventionally, in an engine equipped with a variable valve system, a crankshaft sensor is provided for the crankshaft for detection of a position for each predetermined crank angle, and the variable valve system is used for detection of a reference crank angle position and cylinder discrimination. A first camshaft sensor is provided for the exhaust valve side camshaft whose phase does not change, and a second camshaft is provided for the intake valve side camshaft whose phase is changed by the variable valve device for controlling the variable valve device. A three-sensor configuration in which sensors are provided is adopted.
[0003]
[Problems to be solved by the invention]
However, the mounting of variable valve gears on engines has become common, and the three-sensor configuration is disadvantageous in terms of cost.
Therefore, in synchronization with the rotation of the crankshaft, a position signal is output at a position for each predetermined crank angle, and a position signal is not output at a predetermined reference crank angle position among the positions for each predetermined crank angle. And a camshaft sensor configured to output a cylinder discrimination signal in synchronization with rotation of a camshaft (intake valve side camshaft) whose phase is changed by a variable valve device. As a two-sensor configuration, it has been considered to detect the reference crank angle position from the change in the cycle of the position signal from the crankshaft sensor.
[0004]
However, since the rotational change is large when the engine is started, it is difficult to accurately detect the reference crank angle position from the change in the cycle of the position signal from the crankshaft sensor.
In view of such a situation, the present invention provides a two-sensor configuration in an engine having a variable valve operating device, so that necessary and sufficient functions can be obtained, and the reference crank angle position can be accurately detected when the engine is started. Objective.
[0005]
[Means for Solving the Problems]
Therefore, according to the first aspect of the present invention, the engine is driven by the engine crankshaft via the variable valve gear, and rotates once for every two rotations of the crankshaft, and the phase relative to the crankshaft is advanced or delayed by the variable valve gear. In an engine having a camshaft that is controlled to a maximum retarded angle state at least when the engine is started, the position is detected by detecting a signal output tooth or slit at a position corresponding to a predetermined crank angle in synchronization with the rotation of the crankshaft. A position signal is not output by outputting a signal and removing a tooth or slit at a predetermined reference crank angle position among the positions for each predetermined crank angle to provide a tooth missing portion. The crankshaft sensor configured as described above and the reference crankshaft in a maximum retarded state of the camshaft by the variable valve gear in synchronization with the rotation of the camshaft. In correspondence with the angular position, it provided a cam shaft sensor configured to output a cylinder discrimination signal.
[0006]
As shown in FIG. 1, the operating state determining means for determining when the engine is started and during normal operation after starting, and the reference crank angle position based on the cylinder determining signal from the camshaft sensor when the engine is started. Measure the reference crank angle position detection means for start time to detect and the period of the position signal sequentially output from the crankshaft sensor during normal operation after the start , and the period between the current value and the previous value is measured. And a normal crank angle position detecting means for detecting a reference crank angle position based on the magnitude of the change .
[0007]
The invention according to claim 2 is characterized in that the cylinder discrimination signal of the camshaft sensor has a different number of pulses for each cylinder, and each leading pulse is made to correspond to a reference crank angle position.
In the invention according to claim 3, the starting reference crank angle position detecting means counts a position signal from the crankshaft sensor generated between pulses from the camshaft sensor, and at the time of inputting a pulse from the camshaft sensor. When the count value of the position signal from the crankshaft sensor so far is equal to or greater than a predetermined value, it is determined that the head pulse is used, and the reference crank angle position is detected.
[0008]
In the invention according to claim 4, the reference crank angle position detecting means for normal operation measures the period of the position signal from the crankshaft sensor and sets a period ratio which is a ratio of the current value and the previous value to a predetermined value. Compared to, the reference crank angle position is detected.
[0009]
【The invention's effect】
According to the first aspect of the present invention, the camshaft is controlled to the maximum retarded angle state by the variable valve operating apparatus when starting the engine. In this state, the camshaft sensor is connected to the cylinder corresponding to the reference crank angle position. By configuring so as to output the discrimination signal, the reference crank angle position can be accurately detected based on the cylinder discrimination signal from the camshaft sensor when the engine is started. On the other hand, during normal operation after start-up, since the rotational change is smaller than at start-up, the reference crank angle position can be accurately detected based on the change in the period of the position signal from the crankshaft sensor.
[0010]
According to the second aspect of the invention, the number of pulses of the cylinder discrimination signal of the camshaft sensor is made different for each cylinder, and each leading pulse is made to correspond to the reference crank angle position, thereby detecting the reference crank angle position by the leading pulse. And cylinder discrimination based on the number of pulses can be easily achieved.
According to the third aspect of the present invention, the leading pulse is accurately determined based on the count value of the position signal from the crankshaft sensor generated between the pulses from the camshaft sensor, and the reference crank angle position is determined when the engine is started. It can be detected accurately.
[0011]
According to the invention which concerns on Claim 4, based on the period ratio of the position signal from a crankshaft sensor, a reference | standard crank angle position is correctly detectable at the time of normal driving | operation.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 is a system diagram showing an embodiment of the present invention.
Here, the engine 1 is a four-cylinder engine, and the ignition order is # 1 → # 3 → # 4 → # 2.
[0013]
The intake valve side camshaft 4 and the exhaust valve side camshaft 5 are driven by the crankshaft 2 of the engine 1 via the timing belt 3 and the like. Rotate once for every two rotations of the crankshaft 2.
The intake valve side camshaft 4 is driven by the crankshaft 2 via a variable valve gear (VTC) 6 so that the phase relative to the crankshaft 2 is advanced or retarded. This variable valve operating device 6 controls the phase of the intake valve side camshaft 4 with respect to the crankshaft 2 to a maximum retarded state at least when the engine is started.
[0014]
Here, a crankshaft sensor 7 is provided for the crankshaft 2, and a camshaft sensor 8 is provided for an intake valve side camshaft (hereinafter simply referred to as a camshaft) 4 whose phase is changed by the variable valve gear 6. The signals from these sensors 7 and 8 are input to the control unit 9.
The crankshaft sensor 7 is attached to the crankshaft 2 and rotates, and the teeth are fixed at a fixed position with respect to a signal disk plate having signal output teeth (or slits) at equal intervals (for example, 10 ° intervals) on the outer peripheral side. Is detected and a position signal (POS10) is output. Of the equally spaced teeth, teeth at a predetermined reference crank angle position (180 ° interval) are removed to provide a tooth missing portion. Thus, the position signal (POS10) is not output at the detection position of the missing tooth portion.
[0015]
Accordingly, the position signal (POS10) from the crankshaft sensor 7 is as shown in FIG. 7 (or FIG. 8), and is synchronized with the rotation of the crankshaft 2 at a position corresponding to a predetermined crank angle (for example, 10 ° CA). Although the position signal (POS10) is output, the position signal (POS10) is not output at a predetermined reference crank angle position (180 ° CA interval) among the positions for each predetermined crank angle.
[0016]
The camshaft sensor 8 is attached to the camshaft 4 and rotates. The camshaft sensor 8 is fixed to a signal disc plate having 1 to 4 signal output teeth (or slits) having different numbers at four positions on the outer peripheral side. Thus, the teeth are detected and a cylinder discrimination signal (CAM) having a different number of pulses for each cylinder is output.
Then, each leading pulse of the cylinder discrimination signal (CAM) having a different number of pulses for each cylinder in the maximum retarded state of the camshaft 4 by the variable valve operating device 6 as shown in FIG. The position signal POS10 from the crankshaft sensor 7 is output in correspondence with the non-output position due to the tooth missing portion).
[0017]
Accordingly, the cylinder discrimination signal (CAM) from the camshaft sensor 8 is as shown in FIG. 7 in the maximum retarded state of the camshaft 4 by the variable valve operating device 6, and the phase of the camshaft 4 by the variable valve operating device 6 is as follows. When the angle is advanced, the phase with the position signal (POS10) from the crankshaft sensor 7 changes as shown in FIG.
Next, a crank angle position detection method (particularly, detection of a reference crank angle position and cylinder discrimination) using the crankshaft sensor 7 and the camshaft sensor 8 will be described with reference to the flowcharts of FIGS. FIG. 7 is a time chart at the time of starting the engine, and FIG. 8 is a time chart at the time of normal operation after starting.
[0018]
FIG. 3 is an operation state determination routine, which is executed every predetermined time. This routine corresponds to the operating state determination means.
In step 1 (denoted as S1 in the figure, the same applies hereinafter), it is determined whether or not the start switch is OFF. In Step 2, it is determined whether or not the engine speed Ne is equal to or greater than a predetermined value (for example, 400 rpm).
[0019]
As a result of these determinations, when the start switch is OFF and the engine speed Ne is greater than or equal to a predetermined value, the routine proceeds to step 3 where it is determined that the engine is operating normally after the engine is started, and the start detection flag # FST = 0. .
On the other hand, when the start switch is ON or the engine speed Ne is less than a predetermined value, it is determined that the engine is starting, and the starting detection flag # FST = 1 is set.
[0020]
FIG. 4 shows a cam shaft sensor signal synchronization routine, in which interrupt processing is performed in synchronization with generation of a cylinder discrimination signal CAM (each pulse) from the cam shaft sensor 8.
In step 11, the cylinder discrimination pulse counter CAMCNT for counting the cylinder discrimination signal CAM (each pulse) is incremented by one.
In step 12, it is determined whether or not # FST = 1 (when the engine is started).
[0021]
When # FST = 1 (when the engine is started), the reference crank angle position is detected in steps 13 and 14.
That is, at step 13, the pulse interval counting POS10 counter (count value of the position signal POS10 of the crankshaft sensor between pulses of the camshaft sensor) CNTFST counted as described later is greater than or equal to a predetermined value (for example, 5). If CNTFST ≧ 5, it is regarded as the leading pulse, and the current crank angle position is set at step 14 assuming that the current time is the standard crank angle position (see FIG. 7). This portion corresponds to the starting reference crank angle position detecting means.
[0022]
When # FST = 0 (during normal operation), the reference crank angle position and the leading pulse do not coincide with each other, and thus the reference crank angle position is not detected.
Finally, in step 15, the pulse interval counting counter CNTFST is cleared (CNTFST = 0), and this routine is terminated.
5 to 6 are crankshaft sensor signal synchronization routines, which are interrupted in synchronization with the generation of the position signal POS10 from the crankshaft sensor 7. FIG.
[0023]
In step 21, the pulse interval counting POS10 counter CNTFST is incremented by 1 to count the crankshaft sensor position signal POS10 generated between the camshaft sensor pulses.
In step 22, the period TPOS10 of the position signal POS10 measured in the previous routine is substituted into TPOS10old (TPOS10old = TPOS10).
[0024]
In step 23, the value of the timer for measuring the period of the position signal POS10 is read and this is set as the period TPOS10.
In step 24, the period measurement timer is zero-started for the next measurement.
In step 25, it is determined whether or not # FST = 0 (during normal operation).
[0025]
If # FST = 0 (during normal operation), the reference crank angle position is detected in steps 26-28.
That is, at step 26, a POS10 cycle ratio (= TPOS10 / TPOS10old), which is a ratio between the current value TPOS10 and the previous value TPOS10old of the cycle of the position signal POS10 from the crankshaft sensor, is calculated. Then, in step 27, the calculated POS10 cycle ratio is compared with a predetermined value (for example, 1.5), and if POS10 cycle ratio ≧ 1.5, it is regarded as a tooth missing portion, and the current point is the reference crank angle position. In step 28, the reference crank angle position detection flag # FREF = 1 is set (see FIG. 8). This portion corresponds to the reference crank angle position detecting means for normal operation.
[0026]
When # FST = 1 (when the engine is started), the reference crank angle position is not detected because the reference crank angle position is detected by the camshaft sensor signal synchronization routine of FIG.
In step 29, it is determined whether or not the reference crank angle position detection flag # FREF = 1.
[0027]
When the reference crank angle position detection flag # FREF = 1, the crank angle position detection POS10 counter CRACCNT is cleared in step 30 in order to know the crank angle position by counting the position signal POS10 of the crankshaft sensor thereafter. (CRACNT = 0), and in the next step 31, # FREF = 0.
If the reference crank angle position detection flag # FREF = 0, the crank angle position detection POS 10 counter CRACT is incremented by 1 in step 32.
[0028]
In step 33 (FIG. 6), it is determined whether or not the crank angle position detection POS10 counter CRACNT = 8, that is, whether it is 80 ° CA from the reference crank angle position. This position is determined as a cylinder discrimination position.
If CRACNT = 8, it is the cylinder discrimination position, so in step 34, cylinder discrimination is performed by table search based on the value of the cylinder discrimination pulse counter CAMCNT. That is, for example, as shown in FIG. 7, when CAMCNT = 4, # 2 cylinder (CYLCS = 2), when CAMCNT = 2, # 1 cylinder (CYLCS = 1), when CAMCNT = 1, # In the case of 3 cylinders (CYLCS = 3) and CAMCNT = 3, it is determined that # 4 cylinders (CYLCS = 4). In step 35, the cylinder discrimination pulse counter CAMCNT is cleared (CAMCNT = 0).
[0029]
In step 36, it is determined whether or not the crank angle position detection POS10 counter CRACNT = 12, ie, 120 ° CA from the reference crank angle position. This position is determined as a cylinder discrimination data update position and a control reference position (# 1REF to # 4REF) for fuel injection control and ignition control.
When CRACNT = 12, it is the cylinder discrimination data update position, so in step 37, the control cylinder discrimination counter CYLCNT = CYLCS.
[0030]
With the above control, when the engine is started, as shown in FIG. 7, the camshaft 4 is controlled to the maximum retarded state by the variable valve device 6, and in this state, the camshaft 4 is made to correspond to the reference crank angle position. Thus, the cylinder discrimination signal CAM (leading pulse) is output from the camshaft sensor 8, so that the reference is based on the cylinder discrimination signal CAM (leading pulse) from the camshaft sensor 8 when the engine is started. The crank angle position (#FREF) can be accurately detected.
[0031]
On the other hand, as shown in FIG. 8, during the normal operation, the phase of the cylinder discrimination signal CAM and the position signal POS10 changes due to the operation of the variable valve device 6, but during normal operation, the rotational change is smaller than that at the start. Therefore, the reference crank angle position (#FREF) can be accurately detected based on the change in the cycle of the position signal POS10 from the crankshaft sensor 7 (POS10 cycle ratio).
[0032]
Then, by measuring the position signal POS10 from the crankshaft sensor 7 using such a reference crank angle position (#REF) as a base point, the crank angle position is known based on the count value CRACT, and various controls are performed. It can be carried out.
Further, by knowing the generation position (phase change amount) of the cylinder discrimination signal CAM due to the operation of the variable valve device 6, it is possible to detect the actual operation amount of the variable valve device 6 and to perform feedback control. Needless to say.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing the configuration of the present invention. FIG. 2 is a system diagram showing an embodiment of the present invention. FIG. 3 is a flowchart of an operation state determination routine. FIG. 5 is a flowchart of a crankshaft sensor signal synchronization routine (part 1). FIG. 6 is a flowchart of a crankshaft sensor signal synchronization routine (part 2). FIG. 7 is a time chart at the time of engine start. Chart [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Crankshaft 3 Timing belt 4 Intake valve side camshaft 5 Exhaust valve side camshaft 6 Variable valve gear 7 Crankshaft sensor 8 Camshaft sensor 9 Control unit

Claims (4)

It is driven by a crankshaft of an engine via a variable valve system, and rotates once for every two rotations of the crankshaft. The phase of the crankshaft is advanced or retarded by the variable valve system and controlled to a maximum retarded state at least when the engine is started. In an engine equipped with a camshaft
In synchronization with the rotation of the crankshaft, a position signal is output by detecting a signal output tooth or slit at a position for each predetermined crank angle, and the position for each predetermined crank angle is determined in advance. A crankshaft sensor configured not to output a position signal by removing a tooth or slit at the reference crank angle position and providing a tooth missing portion ;
A camshaft sensor configured to output a cylinder discrimination signal in correspondence with the reference crank angle position in a maximum retarded state of the camshaft by the variable valve device in synchronization with rotation of the camshaft;
An operating state discriminating means for discriminating between the engine starting and the normal operation after starting;
A reference crank angle position detector for starting at the time of starting the engine, which detects a reference crank angle position based on a cylinder discrimination signal from the camshaft sensor;
During normal operation after start- up, the cycle of the position signal output sequentially from the crankshaft sensor is measured, and the reference crank angle position is detected based on the magnitude of the cycle change between the current value and the previous value. Reference crank angle position detecting means for normal operation,
An engine crank angle position detecting device comprising: 2. The crank angle position of an engine according to claim 1, wherein the cylinder discrimination signal of the camshaft sensor has a different number of pulses for each cylinder, and each leading pulse corresponds to a reference crank angle position. Detection device. The starting reference crank angle position detecting means counts a position signal from the crankshaft sensor generated between pulses from the camshaft sensor, and outputs a pulse signal from the crankshaft sensor up to that time when a pulse is input from the camshaft sensor. 3. The engine crank angle position detection device according to claim 2, wherein the reference crank angle position is detected by determining the head pulse when the count value of the position signal is equal to or greater than a predetermined value. The reference crank angle position detecting means for normal operation measures the period of the position signal from the crankshaft sensor, compares the period ratio, which is the ratio of the current value and the previous value, with a predetermined value, and calculates the reference crank angle. The engine crank angle position detection device according to any one of claims 1 to 3, wherein the position is detected.

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