JP2867834B2 - Torque cut mechanism of turbocharged engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque cut mechanism for a supercharged engine having a boost compensator.

[0002]

2. Description of the Related Art A boost compensator is a device for automatically adjusting a fuel injection amount mounted on a supercharged engine. When the amount of intake air sent to a cylinder of an engine increases due to the action of a turbocharger, the amount of fuel is adjusted accordingly. Increase the amount. As a prior art of such a supercharged engine with a boost compensator, there is one disclosed in Japanese Utility Model Laid-Open No. 3-1227. This technology uses a water temperature sensor,
A switching valve connected to a communication path between the boost compensator and the air supply manifold, for selectively connecting the boost compensator to either the air supply manifold or the atmosphere, and a signal from a water temperature sensor are inputted, and the engine cooling water temperature is set to a predetermined value. A control means for opening the boost compensator to the atmosphere by operating the switching valve when the temperature is exceeded, and aims to prevent seizure when the engine is overheated.

[0003]

Well [0007], the boost compensator, as shown in FIG. 4, the pressure determined by the setting of the governor side from the time when the boost pressure is higher than the spring set pressure P ₁ of the operation of the turbocharger in until P ₂ (boost compensator operating region), is a device for increasing correction of the fuel injection amount in accordance with an increase in the intake air quantity. By providing such a boost compensator, a large torque can be obtained by effectively utilizing the function of the supercharger as shown by the solid line in FIG.

However, when a supercharged engine equipped with a boost compensator is installed in a vehicle such as a truck,
When a gear having a deep gear ratio such as an emergency low gear or a reverse gear is selected, the gear or the like may be damaged due to generation of excessive torque. In order to prevent such damage due to excessive torque, an additional device is provided to reduce the torque. However, there is a problem in that the weight is increased and the cost is increased by mounting a new actuator or the like.

An object of the present invention is to provide a torque cut mechanism for a supercharged engine that does not require the installation of a new actuator or the like so that excessive torque can be easily cut.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has a supercharger provided with a boost compensator for increasing the amount of fuel injection in accordance with the amount of intake air. In a torque cut mechanism for an engine, a bypass flow path that branches off from a main flow path that guides air pressure from an engine air supply pipe to the boost compensator at one end and merges again, and a boost air pressure arranged in the bypass flow path and the boost air pressure compensator operating area Pressure control means for adjusting the internal pressure to a predetermined pressure, flow path switching means for selecting either the main flow path or the bypass flow path, and control means for switching the flow path switching means in response to an external signal And a torque cut mechanism for a supercharged engine.

[0007]

According to the above-mentioned means, either the main flow path or the bypass flow path can be selected by switching the flow path switching means in response to an external signal. When the main flow path is selected, the supply pressure is directly guided to the boost compensator. When the bypass flow path is selected, the supply pressure is guided to the boost compensator through the pressure control means. That is, when the bypass flow path is selected, the supply pressure acting on the boost compensator is adjusted to a predetermined pressure in the boost compensator operating area, so that the upper limit pressure is lower than when the main flow path is selected. For this reason, even if the supply pressure increases due to the operation of the supercharger, the pressure that is actually guided to the boost compensator becomes equal to or less than a predetermined value, and the torque correction can be performed by limiting the increase correction of the fuel injection amount. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a torque cut mechanism for a supercharged engine according to the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram showing an example of the structure of a torque cut mechanism. A main passage 3 communicates between an engine intake pipe 1 and a boost compensator 2 so that a supply pressure is guided to the boost compensator 2. I have. The main solenoid valve 4 is provided in the main passage 3 as one of the passage switching means. The bypass flow path 5 branches once from the main flow path 3 so as to sandwich the main solenoid valve 4 and then joins again. The bypass flow path 5 is provided with a bypass solenoid valve 6 as flow path switching means and a regulator valve 7 as pressure control means.

The main solenoid valve 4 and the bypass solenoid valve 6 are switched by a control unit 8 provided as control means such that when one of them is fully opened, the other is fully closed. That is, a signal of the selected gear is input to the control unit 8 as an external signal from the gear position detecting means 9 of the transmission. For example, when a gear with a deep gear ratio such as an emergency low gear or a reverse gear is selected, The solenoid valve 4 is fully closed and the bypass solenoid valve 6 is fully opened to supply the supply air pressure to the bypass flow path 5. On the other hand, when a shallow gear ratio is selected, the main solenoid valve 4 is fully opened and the bypass solenoid valve 6 is fully closed, and the supply air pressure is guided to the main flow path 3.

A regulator valve 7 arranged in the bypass passage 5 adjusts the supply air pressure to a predetermined value in the operating region of the boost compensator 2. That is, as shown in FIG. 2, the boost compensator 2 changes the upper limit pressure P ₂ determined from the set pressure P _{1 of the} spring by the setting condition on the governor side.
It operates in the supply air pressure range up to, but by setting an arbitrary pressure P in this pressure range to the adjustment pressure of the regulator valve 7, the supply air pressure guided to the boost compensator 2 through the regulator valve 7 becomes It is limited from P ₁ in the range of P. For this reason, even when the supply pressure increases due to the operation of the supercharger, the secondary pressure of the regulator valve 7 does not become higher than P, and therefore, the fuel injection amount by the boost compensator 2 is increased. The upper limit of the correction is an increase corresponding to the supply pressure P.

According to the torque cut mechanism of the supercharged engine having the above-described configuration, either the main flow path 3 or the bypass flow path 5 can be selectively switched in response to the transmission gear selection signal.

[0013] Since when the shallow gear ratio is selected to select the main channel 3, the boost compensator 2 is supply pressure increase correction in the range of P ₁ of P _2. This allows
Until it receives a limit set to the governor, the increasing correction of the fuel commensurate with the intake air amount by the supercharging is performed, it is possible to increase the torque until T ₂ in accordance with the increase of the supply pressure (see the broken line in FIG. 2 ).

[0014] On the other hand, since selecting the bypass flow path 5 when the deep gear ratio is selected, the boost compensator 2 boost pressure is increasing correction in the range of P ₁ of P. That is, even when the supply pressure becomes larger than P due to the operation of the supercharger, the amount of fuel increase correction by the boost compensator 2 is limited to the amount corresponding to the supply pressure P. Therefore, the solid line in FIG. As indicated by, the torque does not become larger than T.

Therefore, the torque characteristic of the supercharged engine provided with the torque cut mechanism of the present invention is as shown in FIG.
An arbitrary intermediate point between full boost when the turbocharger is used most effectively and high torque is obtained (indicated by a solid line) and low torque zero boost when the turbocharger is not activated (indicated by a dashed line) The value at the time of operating the torque cut mechanism is set as the value. The torque characteristic at the time of operating the torque cut mechanism can select a desired torque peak by setting the adjustment pressure of the regulator valve 7, and can also appropriately select the torque characteristic by switching the supply pressure flow path. That is, the torque cut mechanism is such that the torque peak under predetermined conditions is lower than at the time of full boost.

In the above-described embodiment, the flow path is switched by using two solenoid valves.
A configuration using a one-way solenoid valve may be used. Further, in consideration of the type and maintenance of the regulator valve, a gate valve, a check valve, and the like may be appropriately installed as necessary.

In the above-described embodiment, the torque is cut in response to the selection gear signal of the transmission in order to prevent the gear from being damaged. It is also possible to control so as to perform an intended torque cut.

[0018]

According to the torque cut mechanism of the turbocharged engine of the present invention described above, the torque can be cut easily with a simple structure that does not require a new actuator or the like, and the excessive torque can be arbitrarily reduced. The torque cut has the effect of greatly improving the durability and reliability of the vehicle. In addition, since the structure is simple, there is no increase in weight and cost.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of the present invention.

FIG. 2 is a relationship diagram between an air supply pressure and a torque showing an operation of the torque cut mechanism of FIG. 1;

FIG. 3 is a torque characteristic diagram of a supercharged engine including the torque cut mechanism of FIG. 1;

FIG. 4 is a diagram showing a relationship between an air supply pressure and a torque showing an operation of a boost compensator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 engine intake pipe 2 boost compensator 3 main flow path 4 main solenoid valve 5 bypass flow path 6 bypass solenoid valve 7 regulator valve 8 control unit 9 gear position detection means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02D 41/02 330 F02D 11/10 F02D 41/04 330

Claims (1)

(57) [Claims] In a torque cut mechanism of a supercharged engine provided with a boost compensator for increasing and correcting a fuel injection amount in accordance with an increase in an intake air amount, a main flow path for guiding a supply pressure from an engine air supply pipe to the boost compensator. A bypass flow path that branches off from the first flow path and merges again, pressure control means disposed in the bypass flow path to adjust the supply pressure to a predetermined pressure in the boost compensator operating area, and the main flow path or the bypass flow path A torque switching mechanism for an engine with a supercharger, comprising: flow path switching means for selecting any one of the following; and control means for switching the flow path switching means in response to an external signal.