JPH03258954A - Intake air pressure detecting device for engine - Google Patents

Abstract

PURPOSE:To always detect the accurate intake air negative pressure independently from the existence of the secondary air supply by changing the intake air negative pressure detection timing at the time of supply and non-supply of the secondary air by a secondary air supply means near an exhaust port. CONSTITUTION:In an intake air pressure detecting device for a rotary piston engine or the like, a detection timing changing means for changing the detection timing, namely, a sampling period of an intake air negative pressure detecting means is provided to change the sampling timing of the intake air negative pressure detection in response to the existence of the secondary air supply by a secondary air supply means near an exhaust port. The intake air negative pressure can be thereby detected with the appropriate timing corresponding to a change of amplitude of the intake air negative pressure pulse fluctuating with the existence of the secondary air supply. Thus, the accurate detection of the intake air negative pressure can be always performed independently from the existence of the secondary air supply, and an engine air-fuel ratio can be controlled accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake pressure detection device for detecting intake pipe pressure of an engine.

(Prior Art) Conventionally, engines in which the fuel injection amount is adjusted by electronic control are equipped with an air flow meter or a hot wire type air sensor to detect the intake flow rate, and the fuel injection amount is adjusted based on the detection signal. Generally, the injection amount is set.

However, since the air flow meter and hot wire type air flow sensor are relatively large, they are disadvantageous in terms of layout, tend to increase intake resistance, and tend to have a delayed response. Therefore, in recent years, as shown in Japanese Patent Laid-Open No. 59-15656, for example, an intake pressure sensor (MAP sensor) that detects the pressure inside the intake pipe has been installed, and based on the pressure detected by this sensor, a data map etc. is used to fuel the fuel. Increasingly, devices that set the injection amount are being adopted.

On the other hand, in general, even in the above-mentioned engines, in order to purify the exhaust gas, fresh air is introduced into the exhaust port of the engine as necessary, and the exhaust gas, which is still in a high temperature state, is converted into oxygen-rich fresh air. A secondary air supply device is provided that burns off (oxidizes) unburned components (hydrocarbons, carbon oxides) contained in the exhaust gas by contacting and mixing the exhaust gas with air.

When supplying such secondary air, it is not always possible to obtain a sufficient purification effect (for example, NOx cannot be treated) if the exhaust gas is purified by simply supplying the secondary air. Recently, in many cases, the secondary air supply device is combined with other after-treatment devices, such as a three-way catalytic converter, to create an efficient exhaust purification system centered on the secondary air supply device. (oxidation and reduction treatment system) is performed.

Particularly in the case of a rotary piston engine, in addition to the exhaust gas purification function described above, supplying secondary air to the exhaust port near the combustion chamber is useful for preventing diluent gas brought into the combustion chamber. It also has the function of substantially reducing the amount of combustion gas and maintaining combustion stability.

Furthermore, in general, recent engines also employ an exhaust gas recirculation system that returns part of the exhaust gas to the intake system and supplies it into the engine combustion chamber to reduce the amount of nitrogen oxides in particular.

By the way, when an exhaust purification system is configured by combining catalytic converters in this way, the amount of exhaust gas components supplied from the engine to the catalytic converter section inevitably varies depending on the operating state (rotation or load range) of the engine. It will be different.

Therefore, the state and amount of secondary air supplied by the secondary air supply device must be properly controlled depending on the operating state of the engine.

From this point of view, as a second prior art, a secondary air control device is provided that variably controls the supply state of secondary air to the exhaust port section or the catalytic converter according to the operating state (operating region) of the engine. is provided (
For example, see Japanese Patent Publication No. 54-35251).

The supply of secondary air in the second prior art is as follows:
For example, this is done by an air pump that is constantly driven by the engine, and the specific supply or non-supply of secondary air, as well as the adjustment of the supply amount itself, are generally controlled in the operating range specified by the throttle opening and engine speed. The shrine is controlled by an air control valve that is controlled accordingly.

(Problem to be Solved by the Invention) However, as described above, secondary air is supplied to the exhaust port in a specific operating region, and the illusion gas diluted thereby is caused to cause some kind of damage as described above. If it is supplied into the engine combustion chamber in the form of
Depending on whether or not the secondary air is supplied, the temperature of the guillotine gas brought into the next intake stroke changes. Naturally, the filling amount of the dilution gas also changes accordingly. In other words, when secondary air is supplied, the exhaust gas is cooled and the residual gas is reduced to zero. The temperature will also drop and the substantial O1 charge will increase.

As a result, the amplitude of the intake negative pressure pulsation changes. Therefore, if intake negative pressure is detected at a normal (always constant) sampling period, for example, only the peak portion shown in Figure 8 will be detected, making it impossible to accurately detect intake negative pressure. This results in fluctuations in the air-fuel ratio.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and includes an intake negative pressure detection means for detecting intake negative pressure;
In an engine configured with a secondary air supply means for supplying secondary air to the vicinity of the exhaust port in a specific operating range, the intake negative The present invention is characterized in that an intake negative pressure detection timing changing means is provided for changing the intake negative pressure detection timing of the pressure detection means.

(Function) The engine intake pressure detection device of the present invention is provided with detection timing changing means for changing the detection timing of the intake negative pressure detection means, that is, the sampling period.
The sampling time for detecting negative intake pressure is changed depending on whether or not secondary air is being supplied by the secondary air supply means.

Therefore, the intake negative pressure can be detected at an appropriate detection timing corresponding to the amplitude change of the intake negative pressure pulsation, which varies depending on the presence or absence of secondary air supply, and erroneous detection can be prevented.

(Effects of the Invention) Therefore, according to the engine intake pressure detection device of the present invention, it is possible to always accurately detect the intake negative pressure regardless of the presence or absence of secondary air supply, and it is possible to accurately control the engine air-fuel ratio. becomes.

(Embodiment) FIGS. 2 and 3 show an engine intake pressure detection device according to an embodiment of the present invention applied to, for example, a rotary piston engine.

First, in FIG. 2, the symbol l indicates, for example, a two-cylinder rotary piston engine main body, and this rotary piston engine main body (hereinafter referred to as the engine main body) 1 has two inner sides as shown in FIG. Trochoid space 2,
Two rotor housings 4, 5 forming a housing 4, 5, and three side housings (a central The common side housing of the parts is especially called an intermezoate housing) 6.
7.8. The trochoid spaces 2.3 of each of the rotor housings 4, 5 are inscribed in the trochoid inner circumferential surfaces 4a, 5a of the rotor housings 4.5 around the eccentric shaft 9, and are mutually 180 degrees apart. Two substantially triangular rotors 10 and 11 that rotate planetarily with a phase difference of degrees are loosely fitted.

Three outer peripheral surfaces 10a to 10cS of the rotors 10 and 11
Three working chambers 13A to 13C and 14A to 44C are formed between 11a=11c and the trochoid inner peripheral surfaces 4a and 5a of the rotor housings 4 and 5, respectively. In addition, the inner circumferential surfaces 4a and 5 of the trophies correspond to the lower part of one side of each of the rotor housings 4 and 5.
An exhaust port 15.16 is opened in g, and the exhaust port 15.16 is commonly communicated with an external exhaust pipe 19 via an exhaust port 17.18.

On the other hand, the side housing located between each of the rotor housings 4 and 5 of the three side housings 6 to 8, that is, the intermediate housing 7, has two intake ports 21 and 22 that communicate with the intake pipe 42, respectively. is opened toward the working chamber in each trochoid space on the side of each of the rotor housings 4 and 5. Also, this intermediate housing 7c has two rotors lO,
Corresponding to the planetary rotation having a phase difference of 180 degrees, one side (front side) of the compression stroke working chamber (any one of 13A to 13C) of the first rotor housing 4 is connected to the other side (front side).
rear side) the intake stroke working chamber of the second rotor housing 5 (
14A-14C), and the other side (rear side), the compression stroke working chamber (14A-14G) of the second rotor housing 5 is connected to one side (front side). ) An intake recirculation passage 25 is formed that alternately communicates with the intake stroke working chamber (any one of 13A to 13C) of the first rotor housing 4 and a second communication state. The intake air recirculation passage 25 can be easily provided by forming a through hole in a predetermined position of the intermezoate housing 7 to communicate between the two trochoid spaces 2 and 3, as shown in FIG. A disc-shaped butterfly-type opening/closing control valve 26 is installed in the center of this intake recirculation passage 25, and this opening/closing control valve 26 is controlled to be fully closed in high-speed, high-load regions. On the other hand, in a low-speed, low-load region, the valve is opened according to the load amount, and the opening cross-sectional area of the intake air recirculation passage 25 is made variable to control the amount of recirculated intake air.

The opening/closing control valve 26 is operated by an opening/closing valve actuator 40 having a diaphragm configuration, which is driven according to the operating state (valve position) of a duty solenoid 41, which is, for example, a three-way solenoid valve, whose operation is controlled by an engine control unit 50, which will be described later. Its opening/closing state is specifically controlled.

On the other hand, the intake ports 21 and 22 are connected to the intake pipe 4, respectively.
2 to the air cleaner 43, and the intake pipe 42
A surge tank 44 is formed in the middle, and a throttle valve 46 is provided in the intake passage between the air cleaner 43 and the surge tank 44.
An intake pressure sensor 45 is installed inside each of them. The intake pressure detection signal PM of the intake pressure sensor 45 is input to the engine control unit 50 ≧ A throttle opening sensor 47 is attached to the throttle valve 46 , and the throttle opening sensor 47 detects the throttle opening. The degree detection signal TVOθ is also manually input to the engine control unit 50. Further, reference numeral 49 denotes a fuel injector, which is provided in the intake pipe 42.

Note that numerals 30 and 31 are sub-intake ports.

Then, the engine control unit 50 inputs the throttle valve opening TVOθ detected by the throttle opening sensor 47, the engine rotation speed He, and the engine coolant temperature Tw, performs a predetermined calculation, and controls the duty solenoid 41. The operating state of the controller is controlled. The duty solenoid 41, which is a three-way solenoid valve, connects the working chamber of the on-off valve actuator 40 having the above-mentioned diaphragm structure to the atmosphere side P1 or the intake pipe 42 side (negative pressure side) P1.
! The driving state (opening/closing of the valve) of the on-off valve actuator 40 is controlled by selectively communicating with either one side of the on-off valve actuator 40 .

On the other hand, near the upstream end of the exhaust passage of the exhaust pipe 19 that discharges exhaust gas from the engine main body l, there is a first catalytic converter 51 and a second catalytic converter 51 located downstream of the first catalytic converter 51 by a predetermined distance. catalytic converters 52 are respectively arranged.

and the first and second catalytic converters 51.5
A first secondary air supply nozzle 53 for supplying port air is provided at the exhaust port 1-15.
There is a second exhaust passage between the two for supplying split air.
One secondary air supply nozzle 54 is provided in each case.

Further, the reference numeral 55 indicates two ports between the first and second secondary air supply nozzles 53.54, the exhaust port 15.16, and the first and second catalytic converters 51 and 52, respectively.
The air pump 55 is an air pump for supplying air, and the air pump 55 is connected to the drive shaft of the engine main body l by a belt, for example, via a pulley with an electromagnetic clutch,
As described later, the connection state of the electromagnetic clutch is controlled by an engine control unit 50 according to the operating state of the engine (see FIG. 7) (not shown).

The air pump 55 is provided with an air control valve (AC) 56 as shown in FIG. The above-mentioned first and second
The supply of secondary air to the secondary air supply nozzles 53 and 54 is controlled according to the engine operating conditions as shown in FIG.

That is, as is clear from FIG. 4, the air control valve 56 communicates the secondary air main supply passage 60 with the first secondary air supply passage 61 and the second secondary air supply passage 62, respectively. On the other hand, it is configured with a relief passage 63, and each of the passages 60 to 63
First and second secondary air control control valves 65 and 66 are disposed at the connection portion of the air conditioner. The first secondary air control control valve 65 has a slidable rod 67
A closed valve is attached to one end of the valve and connects the secondary air main supply passage 60 to the relief passage 63, and the secondary air main supply passage 60 is connected to the first and second secondary air supply passages 61.62. A valve body 68 that switches between two positions including an open position and a valve open position for communication, a spring 69 that biases the valve body 68 toward a closed position, and the rod 67.
a diaphragm 70 connected to the other end; a negative pressure chamber 71 defined by the diaphragm 70; and a negative pressure chamber 71.
The negative pressure chamber 71 is connected to the second negative pressure chamber 71 via the first negative pressure introducing passage 73. It communicates with the intake pipe 42 downstream of the throttle valve 46 in the figure, and in the middle of the first negative pressure introduction passage 73, there is an atmospheric communication passage 74 of the negative pressure chamber 71 or the intake pipe 42 downstream of the throttle valve 46. A first solenoid valve 75 is interposed to mutually switch each communication state to the inside, and the first solenoid valve 75
) When the solenoid valve 75 is turned ON, the negative pressure chamber 71 is opened to the atmosphere, and the valve body 68 is positioned at the closed position by the urging force of the springs 69, 72, and the air pump 5 is turned on.
5, while when the first electromagnetic valve 75 is turned off, the intake negative pressure is introduced into the negative pressure chamber 71, causing the valve body 68 to close to both the springs 69.7.
The air pump 5 is positioned in the valve open position against the biasing force of 2.
5 can be supplied to the first or second secondary air supply passage 61,62.

Further, the second secondary air control control well 66 is attached to one end of the slidable rod 80, and the valve body 68 of the first secondary air control control valve 65 is attached to one end of the slidable rod 80.
is in the valve open position, the secondary air main supply path 6
0 to the first secondary air supply passage 61 and a second valve position that communicates the secondary air main supply passage 61 to the second secondary air supply passage 62. A valve element 82 that switches between positions, a spring 83 that biases the valve element 82 toward the second valve position, a diaphragm 84 connected to the other end of the rod 80, and a A negative pressure chamber 85 is defined, and a second valve body 82 is compressed in the negative pressure chamber 85 and connects a diaphragm 84.
The negative pressure chamber 85 is located on the side of the intake pipe 42 in FIG. 2 from the second negative pressure introduction passage 87 and the first electromagnetic valve 75. It communicates with the intake pipe 42 downstream of the throttle valve 46 via a first negative pressure introduction passage 73 . Further, a second electromagnetic valve 89 is interposed in the middle of the second negative pressure introduction passage 47 to switch the communication state of the negative pressure chamber 85 to the atmosphere communication passage 88 or the first negative pressure introduction passage 73. The second
When the solenoid valve 89 is turned ON, the negative pressure chamber 85 is opened to the atmosphere, and the valve body 82 is positioned at the second valve position by the biasing force of the springs 83 and 86, and the secondary air from the air pump 55 is transferred to the second valve position. The secondary air is supplied to the second secondary air supply nozzle 54 through the secondary air supply passage 62, and when the second solenoid valve 89 is turned off, the intake negative pressure is introduced into the negative pressure chamber 85, so that the valve body 82 is The secondary air from the air pump 55 is supplied to the first secondary air supply near the exhaust port through the first secondary air supply passage 61 by positioning the valve in the first position against the biasing force of the springs 83 and 86. The water is supplied to the nozzle 53.

Further, the first and second secondary air supply passages 61.6
2, the valve body 82 of the second secondary air control control well 66 is in the second valve position.
A bypass passage 90 is formed by a small hole that bypasses the valve body 82 and communicates the upstream and downstream sides of the valve body 82.

In the above configuration, each electrically operated part is controlled by a control signal from the engine control unit b50.

The engine control unit 50 is configured as shown in FIG. 5 (functional block diagram), which will be described later, and includes an example microprocessor (CPU), memory (ROM and RAM), and an interface circuit.

Sunawachi, this engine control unit 50 is
First, the intake negative pressure detection signal PM from the intake pressure sensor 45
and a basic injection pulse width setting circuit 101 that sets the basic injection pulse width of the supplied fuel based on the engine speed detection signal Ne from the engine speed detection means 100, and the engine speed detection signal Ne and the throttle opening sensor. By comparing the throttle valve opening signal TVOθ from 47 with predetermined region reference data on the engine map, the operating state of the engine body 1 can be determined, for example, in the Ag region (highest rotation maximum load) shown separately in FIG. region),
B, area (low rotation, low load area), Bt area (low rotation, high load area), B, area (high rotation, low load area), B4, B,
A region determination circuit 1 that determines whether the region is in one of the regions (high rotation and high load) and outputs an ON signal at the time of the determination.
02, and an AND circuit 104 that passes the oxygen concentration signal O from the oxygen concentration detector 103 when the region determination circuit 102 outputs the above-mentioned B4, B, and the ON signal for determining the region; Oxygen concentration signal passed through 0. A pulse width correction circuit 1 that corrects the basic injection pulse width signal from the basic injection pulse width setting circuit 101 by
05, a fuel injector drive circuit 106 that drives the fuel injector 49 according to the output signal from the pulse width correction circuit 105, and a gate circuit (AND gate) G that outputs an ON signal corresponding to each region of the region determination circuit. , -G, and a solenoid valve control circuit 1 for controlling the supply of secondary air corresponding to the determination area.
07.

In this embodiment, the engine control unit 50 controls the basic fuel injection amount Tp calculated based on the intake air amount detection signal Q and the engine speed detection signal Ne to the exhaust gas only in the high rotation and high load regions B4 and BII. The fuel is injected from the fuel injector 49 with feedback correction based on the residual oxygen concentration in the air, and each area for secondary air supply (A, B, ~ B, ), and based on the determination results, the secondary air control control valves 65 and 6 are respectively
6 by controlling the secondary air supply nozzles 53 .
54 to control the amount of secondary air supplied from each secondary air supply nozzle 53, 54 in accordance with the engine operating range. Moreover, in that case, the on-off control valve 2 of the intake recirculation passage 25 in the secondary air supply region
In the region where 6 is opened (approximately corresponding to the region 84+B i in FIG. 6), secondary air reduction control is performed based on the region determination signal.

Before that, first let's check this engine control unit)50
To explain the general secondary air supply control function of the When the operating state of the engine is in the maximum rotation or maximum load region (air cut region) A, the region determination circuit 102 operates the first solenoid valve 75.
By energizing the valve body 68 of the first secondary air pump control valve 65 to the closed position, the secondary air from the air pump 55 is
Stops the supply of secondary air to the secondary air supply nozzles 53 and 54 (
air force, control). On the other hand, when the opening degree of the throttle valve 46 is in the operating range B (B, ~BS) below the predetermined opening degree θ, the first secondary air is By positioning the valve element 68 of the control valve 65 at the open position, it is possible to supply secondary air to the first and second secondary air supply nozzles 53 and 54 (air supply control).

Of this secondary air supply region B (B, ~BS), first, when the operating state of the engine is in the low rotation low load region B and the high rotation low load region B, the second solenoid valve 8
By stopping the energization to 9 and positioning the valve body 82 of the second secondary air control control valve 66 at the first valve position, the secondary air from the air pump 55 is switched to the first secondary air supply. It is supplied only to the nozzle 53. In these regions, since there are many unburned components in the exhaust gas, the first catalytic converter 51 and the second catalytic converter 52 are both made to function as oxidation catalysts, and the hydrocarbons in the unburned components are removed.
- It is necessary to effectively oxidize carbon oxide, and for this purpose, secondary air is supplied only by the first secondary air supply nozzle 53 to the upstream side of each of the catalytic converters 51 and 52, that is, to the exhaust port 15.16. supply. Also, check the operating state of the engine from the above B, the low rotation high load region B,
During the period from the time when the transition to the second control well 66 for secondary air control occurs until the predetermined time elapses, the second solenoid valve 89 is de-energized in the same way as described above.
By positioning the valve at the first valve position, secondary air is supplied from the first secondary air supply nozzle 53, while in the area 84 after the predetermined time has elapsed, the secondary air is supplied to the second solenoid valve 89. By energizing the second secondary air control valve 66 to position it at the second valve position, secondary air is mainly supplied from the second secondary air supply nozzle 54 and a part of it is bypassed. The first via passage 90
It is also supplied from the secondary air supply nozzle 53 (port leakage area B).

Therefore, in this embodiment, it can be broadly classified into B.

The entire four areas B+ + Bt + B s + B including the area will be considered as a secondary air supply area (port air area) by the first secondary air supply nozzle 53. When a determination output for determining each of these areas is output from the area determination circuit 102, the output is supplied to the solenoid valve control circuit 107 as described above via the gate circuits G, ~G4, and The supply of secondary air is controlled as follows. As will be described later, in this region, the sampling period T of the detection output input of the intake pressure sensor 45 for controlling the fuel injection amount described above is set longer than in other regions.

Next, when the operating state of the engine is in the high rotation and high load region B, the output of the region determination circuit 102 energizes the second solenoid valve 89 to open the second secondary air control control well 66. By positioning the valve body 82 at the second valve position, secondary air from the air pump 55 is supplied to the second secondary air supply nozzle 54 .

That is, since this region discharges a large amount of nitrogen oxides (NOX), at least one of the first and second catalytic converters 51 and 52 requires a reducing atmosphere. Therefore, supply of secondary air to the upstream side of both catalytic converters 51 and 52 by the first secondary air supply nozzle 53 must be avoided. Furthermore, in this case, the required amount of air is smaller than when both the first and second catalysts to, tt are used as oxidation catalysts.

Therefore, only the second secondary air supply nozzle 54 is selected as the secondary air supply nozzle, while supplying secondary air at a low capacity to reduce engine load and improve fuel efficiency. .

Next, the intake negative pressure detection operation and fuel injection amount control operation by the engine control unit 50 will be described in detail with reference to the flowchart No. 6rjXJ.

That is, first, in step S, the output of the intake pressure sensor 45, the throttle opening TVO, and the engine speed N are
Load various control parameters necessary for the following fuel injection amount control such as e.

Next, the process proceeds to step S, where it is determined whether the current operating area is the port air area shown in FIG. 7 described above, and YES.
If it is determined that
sampling period T + (T r = 8 m5ec)
After detecting the intake negative pressure in step S, the basic fuel injection pulse width Tp is calculated.

On the other hand, if a NO determination is made as it is not in the port air region, the process further advances to step S4 to calculate the rate of change TVO(A) of the throttle opening TVO, read the calculated value, and perform the next step based on it. In step S, it is determined whether the current engine operating state is a steady operating state. If the result is YES, indicating that the operation is in a steady state rather than in an unsteady state such as acceleration or deceleration, the process proceeds to step S as described above, and the first sampling period T , (T , =
Detect negative intake pressure with

On the other hand, N is an unsteady state such as acceleration or deceleration.

In this case, priority is given to responsiveness, and the process proceeds to step S, where the second sampling period T in FIG. 8, which is shorter than the first sampling period T, is determined (T, = 4 m5ec
) After detecting the intake negative pressure, the process proceeds to step S to calculate the basic fuel injection pulse width Tp.

Step 1. In step S, the engine intake negative pressure PM and the engine rotational speed Ne detected in accordance with the secondary air supply state as described above are used in step S and step S to calculate the tertiary air pressure shown in FIG. The basic fuel injection pulse width Tp is calculated using the original map.

Next, proceed to step S, where the basic fuel injection pulse width T
The final fuel injection pulse width T is calculated by applying various corrections based on p using the following calculation formula, and the above-mentioned fuel injector 49 is driven by the calculated value T.

The formula for calculating the final fuel injection amount T is as follows.

T=Tp-CAx*・CeA*・a ・(1+KyW+
Ls+KAt+Kpt,)+Ts...
・(1) However, Tp: Basic fuel injection amount CAt5: Intake temperature correction CmAm + atmospheric pressure correction α: O! Air-fuel ratio feedback correction based on sensor output [tw: Water temperature correction 1 [A! l: Start-up correction KAi: Increased amount correction after idling +m: Air-fuel ratio (mixture ratio) increase correction T8: Voltage correction As described above, in the configuration of this embodiment, in the case of the port air region where secondary air is supplied, is a large (long) sampling period T , (T I = 8 m5 ec) compared to T * (T * = 4 m5 ec) for the non-port air region.
ec) to detect the intake negative pressures P and M. Therefore, according to this configuration, accurate intake negative pressure PM corresponding to the amplitude fluctuation of intake negative pressure pulsation depending on the presence or absence of secondary air supply can be obtained.
detection becomes possible, and the air-fuel ratio becomes stable.

For example, when secondary air is supplied, as mentioned earlier, the intake air filling amount substantially increases, so the amplitude of the intake negative pressure pulsation also decreases compared to the case where it is not supplied (solid line in Figure 8). Expanded (
Figure 8 (dashed line). Therefore, for example, as shown in the figure, the sampling period T is as short as in the state where secondary air is not supplied.
If the detection is performed at s=45 seconds, the influence of the peak period will be too large, making it impossible to accurately detect the intake pressure.

However, as mentioned above, the period T , = 4 m5ec
The period is considerably longer (twice as much) as T += 8 m5e
If the detection is performed at c, the above-mentioned large amplitude fluctuation is smoothed out, and it becomes possible to perform stable and accurate detection of the intake negative pressure.

In the above embodiment, the port air area is defined as B in FIG.
, ~B4, generally understood as including all areas,
Although the sampling period is simply switched between two sampling periods, it is of course possible to subdivide this and set the sampling period for each region depending on the difference in the supply amount and supply state of the secondary air, for example.

In addition, in the above embodiment, the case of intake negative pressure pulsation due to secondary air supply peculiar to a rotary piston engine, which was mentioned in the prior art section, was explained as an example, but a similar problem of dilution gas recirculation can be solved, for example. This problem also occurs when secondary air is supplied in a specific operating range when an exhaust recirculation system is adopted for a reciprocating engine or when variable valve timing means are adopted, and the same solution method as above can be applied in those cases as well. can.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to claims of the present invention, Fig. 2 is a system diagram of an engine intake pressure detection device according to an embodiment of the present invention, and Fig. 3 is an intake system structure of an engine main body in the embodiment. A sectional view showing the structure of the air control valve section in FIG. 4 4L of the same embodiment 11tW,
FIG. 5 is a functional block diagram showing the control circuit configuration of the hunt roll unit in the device of the embodiment, FIG. 6 is a flowchart showing the intake pressure detection operation of the control unit, and FIG. The secondary air supply area map, FIG. 8 is a time chart showing the intake pressure detection timing of the device of the same embodiment, and FIG. 9 is a three-dimensional map for setting the basic fuel injection amount. ■・・・Rotary piston engine body 2.3 ・
...Trophyte space 4.5 ...Rotor housing 6.8 ...Side housing 7 ...Intermediate housing tO, U
...Rotor 19...Exhaust pipes 21, 22...Main intake port 25...Intake recirculation passage 26...Opening/closing control valve 40...Opening/closing valve actuator 41・◆・-Duty Lenoid 45..., Air 70 meter 46... Throat/nottle valve 47-◆... Throttle opening sensor Fig. 6 Fig. 7

Claims (1)

[Claims] 1. In an engine comprising an intake negative pressure detection means for detecting intake negative pressure, and a secondary air supply means for supplying secondary air to the vicinity of the exhaust port in a specific operating region, the above-mentioned 2.
An intake air engine characterized in that an intake negative pressure detection timing changing means is provided for changing the intake negative pressure detection timing of the intake negative pressure detecting means depending on whether secondary air is supplied by the secondary air supply means or not. Pressure detection device.