JPS6218735B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust bypass valve control device for a turbocharger using a diaphragm actuator.

For turbocharged internal combustion engines with an intake throttle valve installed upstream of the compressor, the pressure difference between upstream and downstream of the compressor must be maintained below a predetermined value in order to accurately control the intake air amount of the engine. There is.

Therefore, conventionally, for example, as shown in Figure 1,
An intake throttle valve 2 is provided upstream of the compressor 1a of the turbocharger 1, and the pressure in the upstream intake pipe 3a connecting the intake throttle valve 2 and the compressor 1a is transferred to one pressure chamber 4a defined by a diaphragm 4.
and the outlet of the compressor 1a and the engine 5.
A downstream intake pipe 3b connecting the intake manifold 5a of
The pressure inside is guided to the other pressure chamber 4b. Further, the exhaust manifold 5b of the engine 5 and the inlet of the turbine 1b of the turbocharger 1 are connected to an upstream exhaust pipe 6.
The upstream exhaust pipe 6a is connected to the downstream exhaust pipe 6b, which guides the exhaust gas discharged from the turbine 1b to a muffler (not shown), etc., by an exhaust bypass pipe 7 that bypasses the turbine 1b. The exhaust pipe bus valve 8 provided at the upstream end of the exhaust bypass pipe 7 and the diaphragm 4 are connected to a rod passing through the pressure chamber 4a into which the inlet pressure of the compressor 1a, that is, the pressure inside the upstream intake pipe 3a, is introduced. By coupling via 9, compressor 1
When the difference between the inlet pressure and the outlet pressure of a reaches a predetermined value, the diaphragm 4 moves to the right in the figure and the rod 9
The exhaust bypass valve 8 is opened via the exhaust bypass valve 8.

Therefore, an amount of air (air mixture) is fed into the engine 5 in proportion to the opening degree of the intake throttle valve 2, but when the engine 5 is idling or operating at an extremely low load, the compressor 1a is Inlet pressure becomes negative. As a result, the pressure chamber 4a also becomes negative pressure, but in general, taking into consideration the sliding resistance of the rod 9, the opening/closing sensitivity of the exhaust bypass valve 8, etc., the gap is reduced, although it is very small. Since the shaft seal 10 having the shaft seal 10 is attached to the penetration part of the rod 9,
The degree of sealing of the pressure chamber 4a may decrease, and the operability of the engine 5 may deteriorate.

That is, when the engine 5 is operated at low speed and under low load, the inlet pressure of the compressor 1a introduced into the pressure chamber 4a becomes a strong negative pressure, and at the same time, the amount of intake air of the engine 5 is also extremely small. Therefore, in this state, the pressure chamber 4 is leaked from the penetration part of the rod 9 through the shaft seal 10.
When air leaks into the air outlet a, air that does not pass through the intake throttle valve 2 is supplied to the engine 5. In addition, in this type of engine, as shown in FIG. 1, a carburetor or the like is provided as a fuel supply device upstream of the intake throttle valve 2. Therefore, if air that does not pass through the intake throttle valve 2 is supplied to the engine as described above, the air-fuel ratio changes and the stability of the engine deteriorates.

The present invention has been made in view of the above, and when it is detected that the engine is being operated at low speed and low load, the present invention shuts off the air piping etc. that introduces the inlet pressure of the compressor into the pressure chamber. , the air that leaked into the pressure chamber from the shaft seal of the rod,
The purpose is to prevent air from flowing into the intake system without passing through the intake throttle valve, thereby improving operability during low-speed, low-load operation of the engine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments, in which the same parts as those in the prior art are denoted by the same reference numerals.

In the embodiment shown in FIG. 2, a shutoff valve 12 is provided in the middle of the air pipe 1 that introduces the inlet pressure of the compressor 1a into one pressure chamber 4a, and the opening and closing of the shutoff valve 12 is controlled based on the outlet pressure of the compressor 1a. It is something to do. Here, the shut-off valve 12 constitutes an engine operating state detection means and a compressor inlet pressure introduction/blocking means.

In other words, when the engine is operated at low speed and low load,
Since the intake throttle valve 2 is maintained in a nearly fully closed state, the amount of air flowing into the compressor 1a is reduced. Then, even if the compressor 1a is operated at high speed, the outlet pressure, that is, the pressure in the downstream intake pipe 3b, decreases, so when the pressure in the downstream intake pipe 3b falls below a predetermined value, the shut-off valve is activated. 12 is closed, the air pipe 11 is closed, and the upstream intake pipe 3a and the pressure chamber 4a are cut off.

As this shut-off valve 12, those shown in FIGS. 3 and 4 can be used.

That is, the shutoff valve 12 shown in FIG. 3 connects the pressure chamber 12b defined by the diaphragm 12a and the air pipe 13 that leads the pressure in the downstream intake pipe 3b to the pressure chamber 4b of the diaphragm actuator using the signal pipe 14. A valve seat 1 is provided in an intermediate portion of the other pressure chamber 12c which is in communication with each other and defined by the diaphragm 12a.
2d is provided. Then, a valve body 12e facing the valve seat 12d is attached to the diaphragm 12a, and one pressure chamber 12c defined by the valve seat 12d is
is communicated with the upstream intake pipe 3a, and the other pressure chamber 12c is communicated with the pressure chamber 4a of the diaphragm actuator.
While the pressure inside the downstream intake pipe 3b is maintained at a predetermined value or higher, the valve body 12e is opened to communicate the air pipe 11, and when the pressure inside the downstream intake pipe 3b becomes below a predetermined value, the air pipe 11 is closed. There is. 12f is a spring. The signal pipe 14, the diaphragm 12a, the pressure chamber 12b, and the spring 12f function as means for detecting the engine operating state, and the valve seat 12d and the valve body 12e function as means for blocking the introduction of compressor inlet pressure.

The shut-off valve 12 shown in FIG. 4 is composed of a so-called piston valve, and has a valve hole in a valve body 12g that slides depending on the pressure difference between the upstream intake pipe 3a and the downstream intake pipe 3b. 12h. 12i is a spring. The signal pipe 14, the valve body 12g, and the spring 12i function as means for detecting the engine operating state, and the valve body 12g functions as a means for blocking introduction of compressor inlet pressure.

Furthermore, FIG. 5 shows a diagram in which a shut-off valve 12 is incorporated into the dial actuator.
A play is provided between the end of the diaphragm 4 and the rod 9, and a spring 12j for controlling the shut-off valve is stretched between the two. A cylindrical valve seat 12 is attached to the tip of the connecting fitting 15 of the air pipe 11.
A valve body 121 connected to the diaphragm 4 and provided with a
is inserted into the valve seat 12k. Note that the air pipe 13, diaphragm 4, pressure chamber 4b, and spring 12j function as engine operating state detection means,
The valve seat 12k and the valve body 121 function as means for introducing and blocking compressor inlet pressure.

Therefore, when the pressure introduced into the pressure chamber 4b from the downstream intake pipe 3b is above a predetermined value, the play (gap) between the diaphragm 4 and the rod 9 against the spring 12j becomes zero. The valve body 121 moves to the right in the figure and protrudes from the valve seat 12k, thereby communicating the upstream intake pipe 3a and the pressure chamber 4a. Also,
When the pressure inside the downstream intake pipe 3b becomes below a predetermined value,
The diaphragm 4 is separated from the tip of the rod 9 by the tension of the spring 12j. Then, the valve body 121 coupled to the diaphragm 4 is accommodated in the valve seat 12k, so communication between the upstream intake pipe 3a and the pressure chamber 4a is cut off.

In the above embodiment, the engine operating state detecting means detects that the engine is operated at low speed and low load via the pressure in the downstream intake pipe, that is, the outlet pressure of the compressor. As an engine operating state detection means, low speed or low load of the engine is detected through the inlet pressure or outlet pressure of the turbine 1b, or the lubricating oil pressure of the main gear rally in the engine body or in the turbocharger, or the rotational speed of the engine is detected. It may be directly detected, or low-speed, low-load operation may be detected from the opening degree of the intake throttle valve, etc.

As explained above, according to the present invention, during low-speed, low-load operation when the inlet pressure of the compressor becomes a strong negative pressure and the intake air amount of the engine decreases,
Since communication between the compressor inlet and the pressure chamber of the diaphragm actuator is cut off, even if the accuracy of the shaft seal of the rod that passes through the pressure chamber is poor, air that does not pass through the intake throttle valve will still flow into the engine. It is never supplied to Therefore, low speed,
It is possible to stabilize the air-fuel ratio during low-load operation and stabilize the engine.

Further, even if a gap is formed in the shaft seal, there is virtually no air leakage, so the sliding resistance of the rod can be minimized and its movement can be made smoother.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a conventional example, Fig. 2 is a system diagram of main parts showing an embodiment of the present invention, Fig. 3 is a sectional view showing an example of a shut-off valve, and Fig. 4 is a sectional view showing an example of a shut-off valve.
This figure is a cross-sectional view showing another example similar to the above, and FIG. 5 is a cross-sectional view showing an example in which a shut-off valve is incorporated into a diaphragm actuator. 1...Turbocharger, 1a...Compressor, 1b...Turbine, 2...Intake throttle valve, 4...
...Diaphragm, 4a, 4b...Pressure chamber, 7...
Exhaust bypass pipe, 8... Exhaust bypass valve, 9...
Rod, 10... Shaft seal, 11... Air piping,
12...Shutoff valve, 14...Signal piping.

Claims (1)

[Claims] 1 The inlet pressure of a compressor disposed downstream of the intake throttle valve is introduced into one pressure chamber defined by a diaphragm, and the outlet pressure of the compressor is introduced into the other pressure chamber, so that the inlet pressure of the compressor is A turbocharger that connects a diaphragm and an exhaust bypass valve provided in a passage that bypasses the turbine with a rod that penetrates the introduced pressure chamber to prevent the pressure difference between the inlet pressure and the outlet pressure of the compressor from increasing beyond a predetermined value. means for detecting the operating state of the engine; and means for blocking the inlet pressure of the compressor from being introduced into the pressure chamber when it is detected through the means that the engine is being operated at low speed and low load. A turbocharger exhaust bypass valve control device.