JPH0810654Y2 - Auxiliary air supply for engine - Google Patents

Description

The present invention relates to an auxiliary air supply device for an engine, and more particularly to an auxiliary air supply device for an engine that supplies auxiliary air to an exhaust system of the engine by an air pump.

(Prior Art) For example, according to Japanese Patent Laid-Open No. 59-10738, a scavenging port provided between an intake port and an exhaust port of an engine and an air pump are connected by a pressurized air passage, and the pressurized air passage is connected. By providing a timing valve in the middle of the operation, the timing valve is opened and closed at a predetermined timing according to the operating state of the engine, and pressurized air is supplied to the engine side through the pressurized air passage, thereby making the engine idle. It is shown that the rotation speed is maintained at a target rotation speed.

On the other hand, by providing the air pump as described above and connecting the air pump and the exhaust system of the engine by the auxiliary air supply passage, the auxiliary air is supplied to the exhaust system of the engine through the supply passage to generate exhaust gas. Some are designed to be more effective. In this case, the air pump is rotatably driven by being connected to the output shaft of the engine through an electromagnetic clutch or the like, and the auxiliary air supply passage has a predetermined pressure in the supply passage. It is customary to provide a relief valve that protects the air pump and the like by relieving the auxiliary air in the passage when the value exceeds the value.

(Problems to be Solved by the Invention) By the way, as described above, in a configuration in which the auxiliary air is supplied to the exhaust system of the engine by the air pump through the auxiliary air supply passage, the engine is normally operated in a low rotation state. Regardless of the high rotation state, the air pump and the output shaft of the engine are connected by an electromagnetic clutch to operate the air pump with the relief valve provided in the auxiliary air supply passage closed. Therefore, in particular, when the air pump is operated in the high rotation state of the engine, the pressure in the auxiliary air supply passage, that is, the discharge pressure of the air pump, is rapidly increased immediately after the start of the air pump, and the drive resistance is accordingly increased. Was supposed to increase. Therefore, the air pump and the electromagnetic clutch are constantly driven in an overloaded state when the engine is in a high rotation state, which causes problems in reliability and durability of the operation of the air pump and the electromagnetic clutch. .

The present invention addresses the above situation in an auxiliary air supply device in which auxiliary air is supplied to an exhaust system of an engine by an air pump connected to an output shaft of the engine via an electromagnetic clutch. The operation of the air pump or the electromagnetic clutch is prevented by reducing the driving resistance by preventing the discharge pressure of the air pump from rising more than necessary when operating the air pump, especially when the engine is operating at a high rotation speed. The purpose is to improve the reliability and durability of the.

(Means for Solving the Problems) In order to solve the above problems, the present invention is characterized in that it is configured as follows.

That is, an air pump that supplies auxiliary air to the exhaust system of the engine, an electromagnetic clutch that connects the output shaft of the engine and the air pump when a specific operating state is detected, and auxiliary air from the air pump to the exhaust system of the engine. An auxiliary air supply device for an engine, comprising: a relief valve provided in a supply passage for relieving auxiliary air supplied to the supply passage; a predetermined value at least when the output shaft of the engine and an air pump are connected by the electromagnetic clutch. The relief control means for opening the relief valve during the period is provided.

(Operation) According to the above configuration, when the specific operating state is detected, the electromagnetic clutch connects the output shaft of the engine and the air pump to operate the air pump, so that the engine is driven through the auxiliary air supply passage. Auxiliary air will be supplied to the exhaust system, but in this case, the relief control means, at least when the engine output shaft and the air pump are connected by the electromagnetic clutch, for a predetermined period,
By opening the relief valve provided in the auxiliary air supply passage, the auxiliary air in the auxiliary air supply passage is relieved via the relief valve. As a result, in particular, even when the air pump is operated in a high rotation state of the engine, a pressure increase in the auxiliary air supply passage, that is, a rapid increase in the discharge pressure of the air pump is prevented, and the drive is performed. It does not increase resistance unnecessarily. As a result, it is possible to reduce the load on the air pump and the electromagnetic clutch in the high rotation state of the engine, and it is possible to improve the reliability and durability of the operation of the air pump and the electromagnetic clutch.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall system diagram when the auxiliary air supply device according to the present embodiment is applied to a rotary piston engine. As shown, the rotary piston engine 1 has a trochoidal inner peripheral surface. A casing is formed by the rotor housing 2 and the side housings 3 (only one side is shown in the figure) arranged on both sides of the rotor housing 2.
Further, the output shaft (eccentric shaft) 5 is rotationally driven in accordance with the planetary rotational movement of the rotor 4 in the rotor housing 2. An intake port 6 opened at a predetermined position of the side housing 3 and an air cleaner 7 are connected by an intake passage 8. The intake passage 8 is provided with an air flow meter 9, a turbocharger 10, an intercooler from the upstream side. 11, a throttle valve 12 and a surge tank 13 are provided, and a fuel injection valve 14 is attached at a predetermined position of the side housing 3 immediately upstream of the intake port 6. Furthermore, this fuel injection valve 14
And an air bleed 15 passage that connects the intake passage 8 and the upstream side of the throttle valve 12 are provided.
By introducing the air to the fuel injection valve 14 side through the air bleed passage 15, atomization of the fuel injected from the fuel injection valve 14 is further promoted.

Further, one end of an exhaust passage 17 is connected to an exhaust port 16 opened at a predetermined position of the rotary housing 2, and the exhaust passage 17 has a first catalytic converter 18 and a second catalytic converter 19 from the upstream side. Are respectively interposed, and the first and second catalytic converters 18 and 19 purify the exhaust gas by oxidizing HC and CO in the exhaust gas or reducing NOx. . Then, on the downstream side of the second catalytic converter 19,
A silencer (not shown) into which the exhaust gas passing through the catalytic converter 19 is introduced is connected,
An exhaust system 20 is constituted by the silencer, the exhaust passage 17, the first and second catalytic converters 18, 19 and the like.

In the present embodiment, a vane pump type air pump 22 is connected to the air cleaner 7 via a communication passage 21, and both are required between the air pump 22 and the output shaft 5 of the rotary piston engine 1. An electromagnetic clutch 23 is provided for connecting the air pump 22 and the output shaft 5 by the electromagnetic clutch 23 to operate the air pump 22.

Further, the air pump 22 and the exhaust system 20 are connected by an auxiliary air supply passage 24, and the auxiliary air supply passage 24 has a port air supply passage 25 having one end opened to the exhaust port 16 and one end. The second catalytic converter
It is branched into a split air supply passage 26 inserted in 19. An opening / closing valve 28 that is driven to open and close by a negative pressure diaphragm type actuator 27 is provided in the upstream portion of the port air supply passage 25, and an intake negative pressure is introduced into the actuator 27. A control valve 29 for port air is connected, and the control valve 29 and the downstream side of the surge tank 13 in the intake passage 8 are connected by a negative pressure passage 30. Further, an opening / closing valve 32 which is opened / closed by a split air solenoid 31 is provided upstream of the split air supply passage 26.

On the other hand, the auxiliary air supply passage 24 has a relief passage 33
Is formed, the downstream side of the relief passage 33 is connected to the relief silencer 34, and the relief passage 33 is provided with a relief valve 36 that is driven to open and close by a diaphragm type actuator 35. A relief control valve 38 is provided in a communication passage 37 that communicates between the actuator 35 and the auxiliary air supply passage 24, and the auxiliary air supply passage 24 and the diaphragm type are connected with the operation of the control valve 38. By communicating with the actuator 35 of the actuator 35, a part of the auxiliary air, which has a predetermined pressure when the air pump 22 is operated, is actuated via the communication passage 37.
As a result, the relief valve 36 is opened, so that the relief valve 36 is opened.

It should be noted that the port air supply passage 25 and the split air supply passage 26 are provided with check valves 39 and 40, respectively, and the upstream side of the on-off valve 32 provided in the split air supply passage 26 and the relief passage. 33 and 33 are connected by a split relief passage 41.

In addition to the above configuration, in the present embodiment, the intake air amount signal a from the air flow meter 9, the engine speed signal b from the engine speed detection sensor 42, and the air-fuel ratio signal from the O ₂ sensor 43. c and the above throttle valve 12
A control unit 45 to which a load signal d from a throttle sensor 44 arranged near the side of the engine is input is provided. The control unit 45 includes the intake air amount signal a and the engine speed signal b. In addition to calculating the intake air amount per cycle based on the above, the fuel injection amount is set accordingly, and the fuel control signal e is output to the fuel injection valve 14 so as to achieve this fuel injection amount. Based on the air-fuel ratio signal c, the fuel injection amount is feedback-controlled so as to obtain a predetermined air-fuel ratio.

Further, when the control unit 45 detects a specific operating state of the engine 1 based on the engine speed signal b and the load signal d, that is, as shown in FIG. 2, the engine load is P ₁ or less. In addition, when the engine speed is N ₃ or less, it is determined to be the auxiliary air supply region (including the port air supply region and the split air supply region), and the electromagnetic clutch 23 receives the control signal f.
To operate the air pump 22 and output control signals g and h to the port air control valve 29 or the split air solenoid 31 to open the on-off valve 28 or 32 to open the port air. The auxiliary air from the air pump 22 is supplied into the supply passage 25 or the split air supply passage 26.

The port air supply area and the split air supply area in the auxiliary air supply area are determined on the basis of the no-load operation characteristic shown by the broken line in FIG. Also,
As shown in the figure, the engine load is P ₁ or more and P ₂ or less, and the engine speed is N ₃ or less, that is,
In the area shown by the hatched line (a), the air pump 22 is activated and the control signal i is output to the relief control valve 38, so that only the relief valve 36 is opened. Therefore, the auxiliary air is not supplied.
This is an electromagnetic clutch 23 that operates the air pump 22.
This is because the frequency of operation of is suppressed as much as possible.

Next, the operation of this embodiment will be described based on the flowchart of FIG. 3 showing the control operation of the control unit 45. First, the control unit 45 reads the operating state based on the engine rotation signal b and the load signal d in step ₁ , and then determines in step ₂ whether or not it is in the operating region of the air pump 22, and if YES, In step ₃ , it is determined whether or not it is the auxiliary air supply area (see FIG. 2, including the port air supply area and the split air supply area). Then, if YES, it is further determined in step ₄ whether or not it is in the port air supply region, and YES.
If so, the control signal g is output to the port air control valve 29 in step ₅ , and when NO is determined in step ₄ , that is, when the split air supply region is determined, in step ₆ , The control signal h is output to the split air solenoid 31. Then, after that, step ₇ is executed, and it is determined in step ₇ whether or not the area is the relief area. If YES is determined, that is, the second
As indicated by the diagonal lines (b) and (c) in the figure, if the engine is in the split air supply region or the port air supply region and the engine speed is in a relatively high region of N ₂ or more and N ₃ or less, , Relief control valve 3 in step ₈
The control signal i is output to 8 and the control signal f is output to the electromagnetic clutch 23 in step ₉ . As a result, the air pump 22 is activated via the electromagnetic clutch 23 and the port air supply passage 25 or the split air supply passage
Auxiliary air is supplied to 26 and the above relief valve
36 will be opened. Note that when it is determined to be NO in step ₃ above, that is, when it is determined not to be in the auxiliary air supply region, the control unit 45 executes steps ₈ and ₉ .

As described above, in the present embodiment, as indicated by the diagonal lines (b) and (c) in FIG. 2, in the split air supply region or the port air supply region, and in the operating state where the engine speed is high, The relief valve 36 is opened so that an auxiliary air supply passage is provided through the relief valve 36.
The auxiliary air in 24 will be discharged from the relief passage 33. As a result, even when the air pump 22 is operated in the high rotation state of the engine 1, a pressure increase in the auxiliary air supply passage 24, that is, a rapid increase in the discharge pressure of the air pump 22 is prevented. It does not increase the driving resistance. As a result, it becomes possible to reduce the load on the air pump 22 and the electromagnetic clutch 23 when the engine 1 is in a high rotation state.
It is possible to improve the operation reliability and durability of the electromagnetic clutch 23. Further, in this case, the engine speed is high, and therefore the air pump 22 is also in a high speed state. Therefore, even when the relief valve 36 is opened, a sufficient amount of auxiliary air can be secured.

Further, since the load on the air pump 22 and the electromagnetic clutch 23 is reduced, the drive loss of the engine 1 is reduced, which can improve the fuel consumption and the discharge of the air pump 22. The exhaust noise can be reduced by reducing the discharge energy of the auxiliary air discharged from the air pump 22 as the pressure decreases.

The operation of the engine 1 may be controlled such that the relief valve 36 is opened for a certain period of time after the operating state of the engine 1 reaches the port air supply region and the split air supply region shown in FIG. good.

(Advantages of the Invention) As described above, according to the auxiliary air supply device of the present invention, the auxiliary air supply is performed by the relief control means for at least the predetermined period when the engine output shaft and the air pump are connected by the electromagnetic clutch. When the relief valve provided in the passage is opened to relieve the auxiliary air in the auxiliary air supply passage, the air pump is operated, particularly when the air pump is operated in the high rotation state of the engine. A sudden increase in the discharge pressure of the air pump is prevented so that the drive resistance is not increased, whereby the load on the air pump and the electromagnetic clutch in the high rotation state of the engine can be reduced. The reliability and durability of the operation of these air pumps and electromagnetic clutches can be improved. .

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is an overall system diagram of an auxiliary air supply device for an engine according to the present embodiment,
FIG. 2 is a graph showing the auxiliary air supply area, and FIG. 3 is a flow chart showing the control operation of the control unit. 1 …… Engine (rotary piston engine), 5 ……
Output shaft, 20 ... Exhaust system, 22 ... Air pump, 23 ... Electromagnetic clutch, 24 ... Auxiliary air supply passage, 36 ... Relief valve, 38,45 ... Relief control means (relief control valve, control unit ).

Claims (1)

[Scope of utility model registration request] 1. An air pump for supplying auxiliary air to an exhaust system of an engine, an electromagnetic clutch for connecting an output shaft of the engine and the air pump when a specific operating state is detected, and an air pump from the air pump to an exhaust system of the engine. An auxiliary air supply device for an engine, comprising: a relief valve provided in the auxiliary air supply passage for relieving auxiliary air supplied into the supply passage; An auxiliary air supply device for an engine, characterized in that a relief control means for opening the relief valve for a predetermined period at the time of connection with is provided.