JP2687721B2 - Engine valve operation control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operation control device for an engine, and more particularly to a device for switching valve lift characteristics according to operating conditions of the engine.

(Prior art) In order to achieve both improved fuel efficiency at low speed and improved output at high speed, the lift characteristics of the intake valve and exhaust valve are changed according to the operating state, and the intake / exhaust timing or intake / exhaust amount is controlled accordingly. It is known to do so (see, for example, JP-A-63-167016 and JP-A-63-57805).

Explaining this, the main rocker arm whose swing tip contacts the valve and the sub rocker arm adjacent to one side of this rocker arm and having no contact portion with the valve can swing on a common rocker shaft. The main rocker arm is slidably contacted with a low speed cam, and the sub rocker arm is slidably contacted with a high speed cam (having a profile in which an opening angle and a valve lift amount are larger than those of the low speed cam).

When the working oil pressure rises, the main and sub rocker arms are constrained by the pins fitting into each fitting hole by the working oil pressure, and when the working oil pressure weakens, the pins are fitted by the biasing force of the return spring. By pulling out from the abutment hole, the restraint of both rocker arms is released. By restraining and releasing the restraint of both rocker arms,
The cam involved in opening and closing the valve is switched.

(Problems to be Solved by the Invention) By the way, various engine output characteristics are given to each cam, and the first cam set to the low output side (for example, as shown in FIG. The characteristic of the throttle opening with respect to the output torque rises rapidly toward the fully open position) and the second cam set to the high output side (as shown in FIG. 9 the characteristic of the throttle opening with respect to the output torque over the fully open position). There is one that has a gradual rise from the first cam).

In this case, for example, when switching from the first cam to the second cam, in order to maximize the output characteristics of the first cam, the throttle valve is operated to a position near the fully open position,
If the cam is switched to the second cam after that, the torque step at the time of switching the cam is large, and the drivability is deteriorated due to the influence.

On the other hand, in an engine equipped with a throttle opening device capable of arbitrarily changing the characteristic between the accelerator pedal operation amount and the actual throttle opening, the throttle valve is opened at the same time as switching from the first cam to the second cam. By closing,
It is possible to absorb the torque step when switching the cam. However, if the throttle opening / closing device is applied to the one having the first cam and the second cam shown in FIG. 9 and the cam switching from the first cam to the second cam is performed near the fully open position of the throttle valve. However, it is difficult to move the throttle valve in a responsive manner with a throttle actuator having a large throttle operation amount and a small driving force.

Therefore, according to the present invention, by switching to the second cam at a position immediately before the throttle opening characteristic with respect to the first cam changes rapidly, the use range of the throttle opening with good controllability can be maximized when the first cam is used. It is an object of the present invention to provide a device capable of minimizing the torque step when switching to the second cam while ensuring the limit.

If the engine output torque is not the same before and after the cam switching, a torque shock will occur.
As described in Japanese Patent Laid-Open No. 262334, it is common to perform switching at a rotational speed at which the output torque of a low speed cam and the output torque of a high speed cam are the same. However, in the case where the first cam and the second cam shown in FIG. 9 are provided, when the cam switching is performed at the throttle opening degree where the output torque of the first cam and the output torque of the second cam are the same, The output torque and the throttle opening are the same only in the small range where the throttle opening is up to about 10 ° (that is, the range where the broken line characteristic and the solid line characteristic are close to each other) (see also FIGS. 11 and 12). It is not realistic to switch from the first cam to the second cam within this small throttle opening range. Since the controllability is good in the region where the throttle opening characteristic with respect to the first cam changes slowly (the region where the throttle opening is up to about 10 °), it is realistic to use the first cam as much as possible in this region. Because. Therefore, according to the present invention, the cam switching is performed with the throttle opening in which the output torque of the first cam and the output torque of the second cam are not the same, and the cam switching is performed at the timing when the output torques of the two cams are the same. The technical idea is different from that described in the above-mentioned Japanese Patent Laid-Open No. 1-262334.

(Means for Solving the Problems) A first invention is, as shown in FIG. 1 (A), a first cam having a characteristic that a characteristic of a throttle opening with respect to an output torque changes rapidly toward a fully open position, and an output. A variable valve operating device 62 comprising at least two cams, a second cam having a characteristic that the throttle opening with respect to torque changes more slowly than the first cam toward the fully open position, and a mechanism capable of switching these cams, A sensor 63 that detects an engine load equivalent amount (for example, accelerator pedal operation amount α and intake air amount).
And a means 64 for selecting the cam position to be used next according to the operating condition determined based on the sensor detection value.
And the sensor 65 that detects the cam position currently in use.
And means 66 for judging whether or not the cam switching is necessary by comparing the presently used cam position with the cam position to be used next, and the throttle opening characteristic with respect to the output torque of the first cam. Means 70 for setting the throttle opening just before the sudden change as the predetermined opening TVO _K , the sensor 67 for detecting the throttle opening TVO, and the throttle opening when it is determined that the cam switching is necessary. and determining means 68 detects value if located near the predetermined opening TVO _K degrees, the result of this determination, a predetermined detection value of the throttle opening when it is determined that it is necessary to a cam switching when in the close opening TVO _K, then provided a means 69 for outputting a switching signal to the variable valve device 62 to be switched to the cam to be used.

A second invention is, as shown in FIG. 1 (B), a throttle opening / closing device 61 that can change the throttle opening regardless of the operation amount of an accelerator pedal, and a characteristic of the throttle opening with respect to output torque that rapidly increases toward the fully open position. Of the characteristics that change to
A variable valve operating valve including at least two cams, a cam and a second cam having a characteristic in which a throttle opening characteristic with respect to output torque changes more slowly than the first cam toward a fully opened position, and a mechanism capable of switching these cams. A device 62, a sensor 70 for detecting the accelerator pedal operation amount α, a means 64 for selecting a cam position to be used next according to an operating condition determined based on the sensor detection value, and a cam currently in use. A sensor 65 for detecting the position, a means 66 for judging whether or not a cam switching is necessary by comparing the presently used cam position and the next cam position to be used, and an output of the first cam. a means 70 for setting the throttle opening degree immediately before the throttle opening degree characteristic abruptly changes with respect to the torque as a predetermined opening TVO _K, sensor for detecting a throttle opening TVO Means for determining a support 67, whether the detected value of the throttle opening degree when the cam switching is determined to be necessary in the vicinity of the predetermined opening TVO _K
68, and as a result of this determination, when the detected value of the throttle opening when it is determined that the cam switching is necessary is close to the predetermined opening, it is possible to switch to the cam to be used next. Means 69 for outputting a switching signal to the variable valve device 62, means 71 for calculating the engine torque T _K output at the predetermined opening TVO _K by the cam currently in use, and switching to the cam to be used next a means 72 for calculating a target throttle opening TVO _M that is required for outputting the same torque as the torque T _K after the difference between the target throttle opening TVO _M to the predetermined opening degree TVO _K .DELTA.TVO ( = TVO _M -TVO _K) and means 73 for calculating a throttle operation amount, the throttle opening and closing device a drive signal so that only the throttle operating amount ΔTVO simultaneously with the output of the cam switching signal throttle valve is opened and closed
And means 74 for outputting to 61.

(Operation) When the first cam is used and the throttle opening is gradually increased to be fully opened, as shown in FIG. 9, the throttle opening characteristic with respect to the output torque of the first cam changes rapidly. The controllability is good because it is flat until just before (the torque can be greatly changed by a slight throttle operation), but the controllability deteriorates from the position where the throttle opening characteristic with respect to the output torque of the first cam changes rapidly. (The torque does not change much even if a large throttle operation is performed), and the torque step when switching to the second cam becomes larger as the position approaches the fully open position.

In this case, since the first invention switches to the second cam in position (i.e. predetermined opening TVO _K) immediately before the throttle opening degree characteristic for the output torque of the first cam is rapidly changed, the first cam It is possible to minimize the torque step when switching to the second cam, while maximizing the use range of the throttle opening with good controllability during use. First
The cam is used in the partial load range, and the driving feeling is improved by reducing the torque step even at the time of the cam switching performed in the range close to the partial load range.

Further, compared to the case where the first cam is used even after the throttle opening characteristic with respect to the output torque of the first cam changes drastically, the throttle opening characteristic changes more slowly than the first cam toward the fully open position. Controllability is better when using the cam.

When trying to obtain the same torque by operating the throttle valve regardless of the operation amount of the accelerator pedal when switching from the first cam to the second cam, the throttle opening characteristic with respect to the first cam output torque changes abruptly. After that, the throttle valve has to be operated to a greater extent as it approaches the fully open position, so it becomes difficult to move the throttle valve in a responsive manner with a throttle actuator with a small driving force. Since the throttle opening is decreased in accordance with the switching to the second cam at the position immediately before the position where the throttle opening characteristic with respect to the output torque of the cam changes abruptly, the throttle operation amount becomes small, which results in a throttle having a small driving force. Even an actuator can move the throttle valve with good response.

(Embodiment) The variable valve apparatus shown in FIGS. 2 and 3 is a so-called end pivot type, and the configuration itself has already been proposed.

21 is the first cam that emphasizes fuel efficiency, 22 and 23 are second and third cams that emphasize power, 24 is an intake valve (or exhaust valve), 25 is a cam follower part as a roller 26, and this roller 26 is the first cam.
A so-called roller rocker arm that contacts with 21 (a main rocker arm for a sub rocker arm described later), and 27 is a rocker shaft.

The main rocker arm 25 is
Sub rocker arms 28 and 29 are swingably supported,
The second cam 22 is in sliding contact with one sub rocker arm 28, and the third cam 23 is in sliding contact with the other sub rocker arm 29. However, sub rocker arm 29 (also for 28)
Does not have a portion in contact with the valve 24 and is not separated from the cam by the elastic force of the lost motion spring 31, as shown in FIG.

A columnar pin 32 is provided on the swinging portion of one sub rocker arm 28, and a pin 34 having the same axis and the same diameter as the pin 32 is also slidable in the rocker shaft direction on the main rocker arm 25. Provided, return spring 36
Is normally urged downward in FIG. 2 and is in the state shown in FIG. In this state, when the integrally formed cams 21 to 23 rotate, the main rocker arm 25 swings according to the first cam 21, and the intake valve 24 is opened and closed.

In this state, when hydraulic oil is guided to the hydraulic chamber 38 in which the pin 34 is accommodated via the oil passage 40, the two pins 34 and 32 are both pushed up in FIG. 2 against the return spring 36 in the base circle area of the cam. Then, the sub rocker arm 28 enters the main rocker arm 25 in a comb-stab state. In this comb stabbed state, both the main and sub rocker arms
Since the valves 28 and 25 operate integrally, the valve lift characteristics follow the second cam 22. That is, the valve lift characteristic is switched to power-oriented, and the generated torque is increased. Fifth
The figure shows the fully open performance of each of the cams 21 to 23.

The configuration of the other sub rocker arm 29 is the same as that of the one sub rocker arm 28.

The cams 21 to 23 have different profiles so as to satisfy the required valve lift characteristics at the time of partial load, low speed and high load, and high speed and high load, respectively (see FIG. 4). It is formed integrally.

The switching of the hydraulic pressure to the hydraulic chambers 38, 39 is performed by two solenoid valves 45, 46 shown in FIG. Each of the solenoid valves 45 and 46 is a normally closed type. When one of the solenoid valves 45 is opened by an ON signal from the control unit 51 as shown in the figure, the solenoid valve 45 and 46 are moved to a hydraulic chamber 38 for operating the second cam 22. Hydraulic oil is guided from the oil pump, and one valve 45 is closed and the other valve 46 is opened, whereby the hydraulic oil is guided to a hydraulic chamber 39 for operating the third cam 23.

In FIG. 6, a control unit 51 including a microcomputer includes a sensor (for example, a crank angle sensor) 52 that detects an engine speed Ne, a sensor 53 that detects an accelerator pedal operation amount α, and a sensor that detects a throttle opening TVO. 54, the signal from the cam position sensor 58 is input.

The control unit 51 obtains a target throttle opening degree according to the accelerator pedal operation amount α and outputs it to the servo drive circuit 55 at a target timing to perform throttle operation. The servo drive circuit 55 is connected to the throttle valve 57 according to the deviation between the two openings so that the actual throttle opening detected by the throttle opening sensor 54 matches the target throttle opening output from the CPU. The servo motor 56 is driven in forward and reverse directions.

Further, in the control unit 51, the ON / OFF signals are output to the two solenoid valves 45 and 46 to output the cam 2
Although the switching of 1 to 23 is performed, the switching of the cam is not performed at the fully open position of the throttle valve but at a predetermined opening smaller than the fully open position.

In order to perform such cam switching, the flowchart of FIG. 7 (executed every predetermined time (for example, 4 msec)) is created.

The operation of this example will be described with reference to this flowchart. According to the operating conditions at that time, which of the three cams is to be used is set in advance as a map, and this map is shown in FIG. .

In order to refer to this map, the accelerator pedal operation amount α
And the engine speed Ne are read (step 1), and the optimum cam position (cam position to be used next) P _CNEXT for the operating conditions determined from these is obtained from the map in FIG. 8 (step 2).

In step 3, by comparing the cam position currently being used (detected by the cam position sensor) P _CNOW with the cam position P _CNEXT to be used next, it is determined whether or not the cam is being switched (to be exact, the cam switching is performed). Is required) and if so, step 4 is further executed.

That is, even if it is determined that the cam is being switched, the process does not immediately proceed to step 5 to output the cam switching signal, but the throttle opening when the cam is determined to be switched in step 4 is see whether a nearby small predetermined opening TVO _K than the fully open position. For example, it compares the absolute value of the difference between the throttle opening TVO and a predetermined opening TVO _K at that time and a predetermined value epsilon.

As a result of this comparison, if | TVO-TVO _K | <ε, it is determined that the throttle opening is near the predetermined opening TVO _K , and the cam is switched (step 5). If | TVO−TVO _K | ≧ ε, the cam is not switched even if it is determined that the cam is being switched.

Now, in FIG. 9 showing the characteristic of the throttle opening with respect to the output torque, consider the case where the first cam is switched to the second cam by acceleration.

If you switch to the second cam without moving the throttle valve at the fully open position (point B) of the throttle valve,
Since the operating point shifts from the point B to the point D, a large torque step between B and D occurs, and this influences the driving performance to deteriorate.

In contrast, the throttle opening is switched to the second cam in (a position immediately before the curve of the throttle opening degree characteristic rises rapidly for example the first cam (A point)) predetermined opening TVO _K in this example. In this case, the operating point shifts from point A to point C, but the torque step between A and C is smaller than between B and D. By reducing the torque difference,
Deterioration of drivability at the time of cam switching is suppressed.

This is because the throttle opening characteristic with respect to output torque is
This is based on the difference between the first cam that emphasizes fuel efficiency and the second cam that emphasizes power. In other words, regarding the output torque in the region where the throttle valve is opened to some extent (region of approximately 15 ° or more), intake air does not come in even if the throttle valve is opened widely because the valve lift amount is small in the case of the first cam. Therefore, while the curve rises sharply, the second cam, which has a larger valve lift than the first cam, has a large intake of intake air when the throttle valve is wide open, so the curve also rises gently. ing. From the characteristics shown in the figure, the closer the throttle opening at the cam switching point is to the fully open position, the greater the torque step when switching the cam.Therefore, switching the cam on the side with the smaller throttle opening minimizes the torque step. can do. Thus, the characteristic of FIG. 9, the position immediately before the curve of the throttle opening degree characteristic with respect to the first cam rises abruptly to (A point), the throttle opening TVO _K (specifically the cam switching point 15 ° to 20 °).

This is because the cam is not switched in a region (between H and A) where the curve of the throttle opening characteristic is substantially flat, but the controllability is good in this region (the torque can be greatly changed by a slight throttle operation).

Even when the second cam is switched to the first cam by deceleration, it is needless to say that the torque step at the time of cam switching can be made small by switching to the first cam at point C in FIG. .

Next, FIG. 10 is a flow chart of another embodiment.
Here again, in the case of switching from the first cam to the second cam, in this example, in FIG. 9, point A is switched to the second cam with the cam switching point, and at the same time, the throttle valve is moved to a predetermined amount (between A and E) ) It is designed to be small.

When trying to obtain the same torque as before cam switching even if the cam is switched, if the throttle valve is closed in accordance with the cam switching at the fully open position (point B) of the throttle valve as in the conventional example, the throttle valve is closed. The valve must be large, that is, it must be operated only between BF. On the other hand, if the cam is switched at the point A, it is sufficient to operate only between A and E. That is, the throttle operation amount becomes small, and the throttle valve can be moved with good response.

The flowchart for performing such control is the 10th
It is a diagram, and only the portion different from FIG. 7 will be described (this time is also assumed to be the time of switching from the first cam to the second cam), the first cam in step 11 (the cam currently in use)
Calculates the engine torque T _K output at a predetermined opening TVO _K , and then, after switching to the second cam, this torque T _K
It calculates a target throttle opening TVO _M that is required for outputting the same torque (step 12).

For example, according to the map for the first cam shown in FIG. 11, the torque T _K from the predetermined opening TVO _K and the rotational speed Ne, and the
According second map for the cam of Figure 12, it is to determine the target throttle opening TVO _M from the rotational speed Ne and the torque T _K.

Accordingly, the target throttle opening TVO _M and predetermined opening TV
The difference between the _{O K ΔTVO (= TVO M -TVO} K) is Motomari as throttle operating amount (step 13), to close only .DELTA.TVO simultaneously throttle valve and the output of the cam switch signal (step
5,14).

In the embodiment, the case of switching the cam between the first cam and the second cam has been described, but the same applies to the case of switching the cam between the second cam and the third cam.

Further, the example of FIG. 7 does not need to move the throttle valve at the time of switching the cam, so that it can be applied to the case where the accelerator pedal and the throttle valve are mechanically linked.

In addition, FIG. 7, FIG. 10 and FIG. 1 (A), FIG. 1 (B)
In relation to, step 2 is the next cam position selection means.
64, step 3 is cam switching determination means 66, step 4 is determination means 68, step 5 is switching signal output means 69, step 11 is output torque calculation means 71, step 12 is target throttle opening calculation means 72, step 13 Is the throttle operation amount calculation means 73, and step 14 is the drive signal output means 74.

In the embodiment, the description has been made for switching between the first cam and the second cam, but it goes without saying that the same applies when switching between the first cam and the third cam.

(Effect of the Invention) In the first invention, the throttle opening characteristic with respect to the first cam is switched to the second cam at a position immediately before the abrupt change, so that when the first cam is used, the throttle opening with good controllability can be obtained. It is possible to minimize the torque step when switching to the second cam while ensuring the maximum use range.

In the second aspect of the invention, the throttle opening is decreased in accordance with the switching to the second cam at the position immediately before the position where the throttle opening characteristic with respect to the output torque of the first cam suddenly changes, so that the throttle operation amount is small. As a result, even a throttle actuator with a small driving force can move the throttle valve with good response.

[Brief description of the drawings]

1 (A) and 1 (B) are diagrams corresponding to claims of each invention, FIG. 2 is a plan view of a variable valve operating device according to an embodiment, and FIG. 3 is a sectional view taken along line XX of FIG. FIG. 4, FIG. 4 and FIG. 5 are characteristic diagrams of valve lift and full-open torque of this device, FIG. 6 is a control system diagram of the above embodiment, and FIG. 7 is a control operation of this embodiment. FIG. 8 is a flow chart, FIG. 8 is a map characteristic diagram of the cam position, and FIG. 9 is a throttle opening characteristic diagram for explaining the operation when switching the cams. FIG. 10 is a flow chart for explaining the control operation of another embodiment, and FIGS. 11 and 12 are map characteristic diagrams of output torques for the first and second cams. 21 ... first cam, 22 ... second cam, 23 ... third cam, 25 ... main rocker arm, 28,29 ... sub rocker arm, 32-3
5… Pin, 38,39… Hydraulic chamber, 45,46… Solenoid valve, 5
1 ... control unit, 52 ... crank angle sensor (engine speed sensor), 53 ... accelerator pedal operation amount sensor, 54 ... throttle opening degree sensor, 55 ... servo drive circuit,
56 ... Servo motor, 57 ... Throttle valve, 58 ... Cam position sensor, 61 ... Throttle opening / closing device, 62 ... Variable valve operating device, 63 ... Engine load equivalent amount sensor, 64 ... Next cam position selecting means, 65 ... Cam position sensor , 66 ... Cam switching determination means, 67 ... Throttle opening sensor, 68 ... Determination means, 69 ... Drive signal output means, 70 ... Accelerator pedal operation amount sensor, 71 ... Output torque calculation means, 72 ... Target throttle opening calculation Means, 73 ... Throttle operation amount calculation means, 74 ... Drive signal output means.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02D 41/10 310 F02D 41/10 310 43/00 301 43/00 301Z 301K 45/00 330 45/00 330

Claims (2)

(57) [Claims] 1. A first cam having a characteristic that a throttle opening characteristic with respect to output torque changes abruptly toward a fully open position,
A variable valve operating device comprising at least two cams, a second cam having a characteristic that the throttle opening degree with respect to the output torque changes more slowly than the first cam toward the fully open position, and a mechanism capable of switching these cams. Depending on the sensor that detects the load equivalent of the engine and the operating condition that is determined based on this sensor detection value,
Means for selecting the next cam position to be used, a sensor for detecting the cam position currently in use, and switching of the cam are required by comparing the cam position currently in use with the cam position to be used next. Means for determining whether or not the throttle opening degree immediately before the throttle opening characteristic with respect to the output torque of the first cam suddenly changes, and a sensor for detecting the throttle opening degree. And means for determining whether or not the detected value of the throttle opening when it is determined that the cam switching is necessary is near the predetermined opening, and as a result of this determination, the cam switching is required. If the detected value of the throttle opening when it is determined that the value is close to a predetermined opening, a switching signal is sent to the variable valve device so that the cam to be used next can be switched. Valve operating control apparatus for an engine, characterized in that a means for force. 2. A throttle opening / closing device capable of changing the throttle opening regardless of the operation amount of the accelerator pedal, a first cam having a characteristic that the characteristic of the throttle opening relative to the output torque changes rapidly toward the fully open position, and the output torque. A variable valve operating device comprising at least two cams, a second cam having a characteristic that the throttle opening degree with respect to the above changes more gradually than the first cam toward the fully open position, and a mechanism capable of switching these cams, and the accelerator. Depending on the sensor that detects the pedal operation amount and the driving condition that is determined based on this sensor detection value,
Means for selecting the next cam position to be used, a sensor for detecting the cam position currently in use, and switching of the cam are required by comparing the cam position currently in use with the cam position to be used next. Means for determining whether or not the throttle opening characteristic immediately before the throttle opening characteristic with respect to the output torque of the first cam changes rapidly, and a sensor for detecting the throttle opening. And means for determining whether or not the detected value of the throttle opening when it is determined that the cam switching is necessary is near the predetermined opening, and as a result of this determination, the cam switching is required. If the detected value of the throttle opening when it is judged to be close to a predetermined opening, a switching signal is sent to the variable valve device so that the cam to be used next can be switched. Means, a means for calculating the engine torque output at the predetermined opening by the cam currently in use, and a means for outputting the same torque as this torque after switching to the cam to be used next. Means for calculating a target throttle opening degree, means for calculating a difference between the target throttle opening degree and the predetermined opening degree as a throttle operation amount, and at the same time as the output of the cam switching signal, the throttle valve is operated by this throttle operation amount. And a means for outputting a drive signal to the throttle opening / closing device so that the valve is opened / closed.