JPH03121216A - Pressure detecting device - Google Patents

Abstract

PURPOSE:To keep the temperature of an air reservoir equal to the intake air temperature to prevent faulty detection due to dew condensation, by forming the reservoir in an intake pipe of an internal combustion engine through a throttle-hole, and connecting both ends of an intake air conduit pipe respectively to a pressure detecting device body and the air reservoir. CONSTITUTION:Intake air of an engine 10 is introduced into a cylinder through an air cleaner 13, a throttle valve 14, and a surge tank 15 forming a part of an intake pipe 12. Intake air pressure in the surge tank 15 is detected by a pressure detecting device 18. In this case, the pressure detecting device 18 is formed as follows: the upper wall of the surge tank 15 is partitioned by a wall material 19a to form an air reservoir 19. To the air reservoir 19, the surge tank 15 is connected through a throttle-hole 20 formed in the wall material 19a and a pressure detecting device body 32 through an intake air conduit pipe 33. The temperature of the air reservoir 19 is thus kept equal to the intake air temperature of the engine 10 to prevent dew condensation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure detection device, and more particularly to a pressure detection device for detecting intake pressure of an internal combustion engine.

[Prior Art] Conventionally, as shown in FIG. 7, in the intake system of an engine 1 (internal combustion engine), outside air is sucked into a surge tank 4 downstream of a throttle valve 3 via an air cleaner 2, and the surge is absorbed into a surge tank 4 downstream of a throttle valve 3. Air from tank 4 is supplied to each cylinder of engine 1.

A pressure detection device 5 is used to measure the intake pressure to the engine 1. In this pressure detection device 5, a pressure detection device main body 6 having a semiconductor diaphragm etc. is connected to a surge tank 4 through an air conduit 8 having a gas filter 7 in the middle.
It has a connected form. The gas filter 7 houses a filter material (non-woven fabric or the like) 7a inside. and,
The filter material 7a prevents solids in the intake air from entering the pressure detection device main body 6 side. The intake pressure of the engine 1 is directly detected by the pressure detection device main body 6 via the filter material 7a of the gas filter 7 and the air conduit 8.

[Problems to be Solved by the Invention] However, in such a pressure detecting device 5, when the outside air temperature is low, the pressure detecting device 5 becomes low temperature, and as the intake pressure of the engine 1 changes, the pressure detecting device 5 draws air directly to the pressure detecting device 5. The air is cooled inside the air conduit 8 of the pressure detection device 5 and becomes below the dew point temperature, generating dew condensation water. The problem arises that accurate pressure detection cannot be performed due to the generation of condensed water. In particular, as shown in FIG.
When R is used, that is, when part of the exhaust gas from the engine 1 is recirculated to the intake side, hot and humid air enters the intake air, which tends to cause dew condensation.

One method for preventing the deterioration of pressure detection accuracy due to condensed water is disclosed in, for example, Japanese Utility Model Application Laid-open No. 59-35677. In this method, a liquid reservoir is provided in the air conduit, and the main body of the pressure detection device is located above the liquid reservoir.

However, even in this method, there is a problem in that the air pressure in the surge tank directly enters the air conduit, so that the air conduit is cooled at the outside temperature, and dew condensation water is generated within the air conduit.

An object of the present invention is to provide a pressure detection device that can prevent condensation and always accurately detect suction pressure.

[Means for Solving the Problems] The present invention provides an air storage chamber in an intake pipe of an internal combustion engine, which has a predetermined capacity sufficient to temporarily retain air coming from the intake pipe through a throttle hole, The gist of this is a pressure detection device in which one end of an air conduit that guides the pressure in the intake pipe is connected to a pressure detection device main body, and the other end of the air conduit is connected to the air storage chamber.

[Operation] Since the air storage chamber is provided in the intake pipe of the internal combustion engine, the air storage chamber is kept at the same temperature as the intake air of the internal combustion engine,
Condensation is prevented when intake air moves into the air storage chamber due to pressure fluctuations.

[Embodiment] An embodiment embodying the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an intake pipe 11 and an exhaust pipe 12 are connected to an engine (internal combustion engine) 10, and intake air is passed through an air cleaner 13, a throttle valve 14, and a surge tank 15 that forms part of the intake pipe. introduced into the cylinder. In addition, the exhaust pipe 12 and the surge tank 15 are connected to the EGR conduit conduit 16.
The EGR conduit 16 is connected to the EGR conduit 16 and an EGR control valve 17 is provided. By operating the EGR control valve 17, a portion of the exhaust gas from the engine 10 is recirculated to the surge tank 15.

Also, the intake pressure in the surge tank 15 is detected by the pressure detection device 18.
It is now detected by This pressure detection device 18 will be explained in detail below.

An air storage chamber 19 is formed on the inner wall of the upper surface of the surge tank 15 and is partitioned by a wall material 19a.

The space capacity V2 of this air storage chamber 19 is determined by the following equation.

V2≧Vl ((P2-PI)/P2) However, Vl: Piping volume of the pressure detection device P1: Minimum pressure inside the surge tank during EGR operation P2: Maximum pressure inside the surge tank during EGR operation or air storage A throttle hole 20 is formed in the wall material 19a of the chamber 19, and the inside of the air storage chamber 19 and the inside of the surge tank 15 communicate with each other through the throttle hole 20. Furthermore, a screw hole 21 is formed in the wall material 19a of the air storage chamber 19 that is in contact with the outside air, and passes through the wall material 19a.

As shown in FIG. 2, the gas filter 22 has a connecting portion 23.
A case 23 having a shape and a lid member 24 having a connecting portion 24a.
and a locking protrusion 2 provided on the outer periphery of the case 23.
3b and the engagement recess 24b provided in the lid member 24 engage with each other, thereby connecting the two 23 and 24. A conduction hole 25 and a filter material storage chamber 26 are formed in the case 23.
and a conduction hole 27 formed in the lid member 24 are in communication with each other. In the filter medium storage chamber 26, a nonwoven fabric 30 and a wire mesh 31 are placed one on top of the other via stays 28 and 29. Incidentally, the case 23 is made of resin, and the lid member 24 is made of metal.

A screw is formed on the outer periphery of the connecting portion 24a of the gas filter 22, and this connecting portion 24a is connected to the screw hole 21 of the air storage chamber 19.
It is screwed on. Furthermore, an air conduit 33 having one end connected to a pressure detection device main body 32 is connected to the connection portion 23a of the gas filter 22. The pressure detection device main body 32 has a built-in semiconductor diaphragm and the like.

When detecting the intake pressure using the pressure detection device 18 installed in this way, the intake pressure in the surge tank 15 is measured by checking whether the intake pressure in the surge tank 15 is detected by the throttle hole 20, the air storage chamber 19, the wire mesh 31, the nonwoven fabric 30, or the air conduit 33. The pressure is detected by the pressure detection device main body 32 via the pressure detection device main body 32.

At this time, the air storage chamber 1 arranged in the surge tank 15
9 becomes equal to the intake air temperature of the engine, and even if the intake air pressure fluctuates, gas exchange (movement) ends within the air storage chamber 19, and since the air storage chamber 19 itself is equal to the intake air temperature, condensation does not occur. There isn't.

To explain in more detail, FIG. 3 shows the surge tank 15.
The temperature measurement results at each measurement point P1 to P5 from to the pressure detection device main body 32 are shown. In this case, the air temperature in the surge tank 15 was 16°C and the relative humidity was 38%, so the dew point temperature was 3.6°C. Also, measurement point P
4 is the maximum intake air intrusion location due to intake pressure fluctuations when the air storage chamber 19 is not provided.

The following can be seen from this Figure 3. In other words, air storage chamber 1
If 9 is not provided, dew condensation will occur in the area where the temperature is below the dew point temperature (the area surrounded by A1, A2, and A3 in FIG. 3) due to pressure fluctuations. However, by providing the air storage chamber 19, there is no region where the temperature drops below the dew point due to pressure fluctuations.
No condensation occurs. That is, in FIG. 3, A4. A5. A6
．． The area surrounded by A7 can be set at a temperature equal to or higher than the dew point temperature.

In this way, the temperature inside the surge tank 15 is high due to the EGR gas, the heat of the engine, etc., and the temperature inside the surge tank 15 is maintained at the dew point or higher, so that no dew condensation occurs.

As described above, in this embodiment, the air coming from inside the surge tank 15 through the throttle hole 20 is temporarily retained in the surge tank 15, which forms a part of the intake pipe of the engine 10 (internal combustion engine), as much as possible. An air storage chamber 19 having a predetermined capacity was provided, and one end of an air conduit 33 was connected to the pressure detection device main body 32, and the other end of the air conduit 33 was connected to the air storage chamber 19. As a result, dew condensation during gas exchange (movement) in the air storage chamber 19, which has a temperature equal to the intake air temperature of the engine 10, is prevented, and intake pressure can always be accurately detected. In particular, EGR
When using the EGR gas, humid air is sucked into the surge tank 15, but it is similarly cooled in the air storage chamber 19 and becomes over 100% (reaches saturation), causing dew condensation. This prevents the problem of not being able to detect pressure.

Note that this invention is not limited to the above embodiments,
For example, as shown in FIG. 4, fresh air may be introduced into the air storage chamber 19 to lower the humidity of the humid gas entering the air storage chamber 19, thereby lowering the dew point temperature. In this case, it is very effective in engines where the humidity inside the surge tank is low. Furthermore, as shown by the broken line in FIG. 4, fresh air is introduced into the air storage chamber 19 at a position close to the throttle hole 20 to reduce the humidity of the gas in the surge tank that moves into the air storage chamber 19 due to pressure fluctuations. It may be lowered.

Further, in the above embodiment, the air storage chamber 19 was provided on the side (on the top surface of the surge tank), but as shown in FIGS. 5 and 6,
When installing on the side (on the side of the surge tank), provide multiple throttle holes 20 for the air storage chamber 19.
It may also be possible to drain condensed water if it accumulates.

Furthermore, as shown in FIG. 4, the air storage chamber 19 may be fixed within the surge tank 15 (intake pipe) with bolts 34.

[Effects of the Invention] As described in detail above, the present invention exhibits an excellent effect of preventing dew condensation and always accurately detecting suction pressure.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the installation state of the pressure detection device of the embodiment, Fig. 2 is a cross-sectional view showing the vicinity of the gas filter, Fig. 3 is a diagram for explaining temperature distribution, and Fig. 4 is a cross-section of another example. 5 is a sectional view of another example, FIG. 6 is a side view of another example, and FIG. 7 is a diagram for explaining a conventional pressure detection device. 10 is an engine (internal combustion engine), 15 is a surge tank, 1
9 is an air storage chamber, 20 is a throttle hole, 32 is a pressure detection device main body, and 33 is an air conduit.

Claims (1)

[Claims] 1. In the intake pipe of an internal combustion engine, an air storage chamber having a predetermined capacity that can temporarily retain the air coming from the intake pipe through the throttle hole is provided, and one end of the air conduit that guides the pressure in the intake pipe is provided. A pressure detection device, characterized in that it is connected to a main body of the pressure detection device, and the other end of an air conduit is connected to the air storage chamber.