Electronic control throttle device for internal combustion engine
Technical Field
The present invention relates to a throttle device for an internal combustion engine (engine), and more particularly to an electronically controlled throttle device in which a throttle valve is driven by an electric actuator such as a motor.
Background
Conventionally, there has been known an electronically controlled throttle device for controlling a throttle valve of an internal combustion engine by an electric actuator such as a motor.
However, such an electronically controlled throttle device basically controls the intake air of the engine by driving an electric actuator to open a throttle valve having a return spring based on an opening degree signal from a throttle sensor and a control signal from an ECU.
Therefore, if the power supply to the electric actuator is unexpectedly cut off during traveling, the throttle valve returns to the fully closed position by the biasing force of the return spring, and the vehicle may fall into a state where it cannot travel after a rapid deceleration. When the throttle valve is left for a long time in a fully closed state during the stop of the engine, a combustion product (tar or soot) in the intake pipe adheres between the throttle valve and the inner wall of the intake pipe to stick the throttle valve and the intake pipe together, and the throttle valve cannot be opened by the starting torque of the electric actuator. In an electronically controlled throttle device that controls a throttle valve by an electric actuator, safety assurance (limp-home mode) when the actuator fails is a significant issue.
In order to solve this problem, for example, japanese patent application laid-open No. 2003-370002 (patent document 1) and the like disclose a device in which a guarantee stopper is provided to prevent the throttle valve from being fully closed when the electric actuator fails to rotate the throttle valve in the fully closing direction by the urging force of the return spring. However, these safeguard stoppers utilize motor drive control to suppress the force of the return spring to slowly return to the fully open position, require various sensors or electronic devices and require complicated control, and have a problem of additional consumption of motor drive power.
In this regard, for example, japanese patent application laid-open No. 2002-256894 (patent document 2) and the like disclose an electronically controlled throttle device for an internal combustion engine, which has two kinds of springs, a return spring for returning a throttle valve to a throttle portion and a preset spring (Default spring) for returning the throttle valve from a fully closed state to an opening degree to which the throttle valve can move by itself (preset opening degree), for controlling an intake air amount.
However, in the electronic control throttle device using the above-described conventional preset spring, there is a problem in that when the throttle valve is closed, the resonance caused by the return spring causes mutual friction between the adjacent wires or friction of the guide, and is damaged.
Therefore, a method of suppressing the amplitude by making the interval of the guide in the return spring as narrow as possible, a method of eliminating the overlapping of the resonance points by a compression spring having a high thrust load and a high spring constant by increasing the interval between the wires, or the like is generally adopted, but the method for preventing the resonance caused by the above-described conventional return spring has problems that the design and assembly are difficult, or an expensive spring is required.
On the other hand, in, for example, a highly supercharged engine or the like, in order to ensure the sealing property of the throttle shaft at the portion supported by the throttle body, it is necessary to use a pressure-resistant (high-strength) sealing member, however, in this case, as shown in fig. 6, compared with the case where the sealing member is not used or the case where the sealing member of usual strength at present is used, there is a large friction force in opening and closing, and as the hysteresis of opening and closing of the valve increases, the life of the motor in the opening direction decreases, the problem of delaying the return speed in the closing direction, on the other hand, when the friction force of the sealing member is reduced, in the highly supercharged engine, durability is deteriorated due to deterioration of sealing performance, and in particular, when a spring having a high spring constant is used as the return spring, durability is further deteriorated because a larger torque is required for the throttle shaft.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2003-370002
Patent document 2: japanese laid-open patent publication No. 2002-256894
Disclosure of Invention
Problems to be solved by the invention
The present invention relates to an electronic control throttle device for an internal combustion engine, in which a throttle gear for transmitting a driving force from an electric actuator disposed in a throttle body in a direction to open a throttle valve is fixed to a base end portion of a throttle shaft pivotally supported by the conventional throttle body and having a throttle valve, a connecting rod is disposed between the throttle gear of the throttle shaft and the throttle body so as to be rotatable within a predetermined range with respect to an axial direction and movable in the axial direction, the connecting rod is locked to the throttle body so as to restrict rotation in a preset state, a return spring for returning the throttle valve to a preset position when the driving force from the electric actuator is shut off is coupled between the throttle gear and the throttle body, in addition, a link spring is connected between the link and the throttle gear, and the electronically controlled throttle device is capable of using a return spring having a spring constant matching the sealing performance of a sealing member used for the return spring, preventing the reduction of the life of the motor even when a high-pressure-resistant seal is used, and preventing damage by reducing friction due to resonance of the return spring.
Means for solving the problems
In order to solve the problem, the electronically controlled throttle device for an internal combustion engine of the present invention is characterized in that the return spring is disposed on an outer periphery of the connecting rod spring, and a load of the connecting rod spring in a thrust direction is set to be larger than a load of the return spring in the thrust direction.
According to the present invention, since the return spring having a low spring constant can be set, it is possible to prevent an increase in torque applied to the throttle shaft.
Further, by setting the load of the connecting rod spring in the thrust direction to be larger than the load of the return spring in the thrust direction, the connecting rod is pressed against a seat of a throttle shaft formed on the throttle body by the reaction force of the connecting rod spring, whereby the resonance generated when the return spring is operated (returned) is suppressed by restricting the thrust position.
In particular, in the present invention, the return spring is set to be in a tightly wound state at the time of assembly or in a tightly wound state in accordance with the rotational operation of the throttle valve, and the link rod is movable while operating, whereby the resonance generated by the return spring at the time of return operation can be absorbed and suppressed reliably.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, the spring constant of the return spring can be optimally designed according to the friction of the seal member, the resistance when the throttle valve is operated in the opening direction can be reduced to increase the life of the motor, the throttle valve can be reliably returned in the closing direction to prevent a return failure, and the resonance of the return spring generated at the time of closing can be suppressed.
Drawings
Fig. 1 is a perspective view showing an exploded state of a preferred embodiment of the present invention.
Fig. 2 is a longitudinal sectional view of the embodiment shown in fig. 1.
Fig. 3 is a cross-sectional view of the embodiment shown in fig. 1.
Fig. 4 is a front view of the preset position and the fully open position of the valve in the embodiment shown in fig. 1 and an explanatory diagram showing states of the return spring, the connecting rod, and the connecting rod spring at the respective positions.
Fig. 5 is a graph showing a relationship between the valve opening degree and the torque of the throttle shaft in the embodiment shown in fig. 1.
Fig. 6 is a graph of the relationship between the valve opening degree and the torque of the throttle shaft in the related art example.
Description of the reference numerals
1 throttle valve body, 2 throttle valve, 3 throttle valve shaft, 4 sealing member, 5 support, 6 electric actuator, 7 throttle gear, 8 connecting rod, 9 reset spring, 10 connecting rod spring, 11 air inlet channel, 12 shaft hole, 13 support, 14 shell, 15 receiving recess, 16 stop protrusion, 31 stop screw, 32 front end part, 33 base end part, 61 rotating shaft, 62 speed reducing gear, 63 rotating gear, 71 gear part, 72 recess, 81 stop protruding piece, C air inlet channel central axis
Detailed Description
Fig. 1 to 3 show a preferred embodiment of the present invention, in a throttle body 1 cast of a light alloy such as aluminum, an intake passage 11 is formed so as to penetrate therethrough, the intake passage 11 is cylindrical and connected to an intake pipe (not shown) of an internal combustion engine (engine), a throttle shaft 3 is pivotally supported on the throttle body 1 so as to be orthogonal to a central axis C of the intake passage 11, a circular throttle valve 2 is fixed to the throttle shaft 3 by stopper screws 31, and the throttle valve 2 is inscribed in the intake passage 11 and opens and closes intake air.
More specifically, the front end portion 32 of the throttle shaft 3 is supported by a bearing 13 in a shaft hole 12 formed in a wall surface of the intake passage 11, the base end portion 33 of the throttle shaft 3 is pivotally supported by a cylindrical seal member 4 and a bearing 5 serving as a bearing, and the seal member 4 is disposed on a side (for example, a front surface side) opposite to the bearing 13 of the intake passage 11, so that the throttle shaft 3 is supported by the intake passage 11 in a sealed state and can smoothly rotate.
In the housing 14 formed below the intake passage 11 of the throttle body 1, the electric actuator 6 as a motor is housed in the housing recess 15 in a state where the rotating shaft 61 is exposed from the housing recess 15 formed in the front surface of the housing 14.
Further, a throttle gear 7 is fixed to a base end portion 33 of the throttle shaft 3 exposed from the recess 15 in the front surface of the throttle body 1, the throttle gear 7 having a circular arc plate-shaped gear portion 71, the gear portion 71 meshing with a rotary gear 63 fixed to a rotary shaft 61 of the electric actuator 6 via a reduction gear 62, and a connecting rod 8 having a thin cylindrical outer shape is inserted and fitted between the carrier 5 and the throttle gear 7 so as to be movable in the axial direction at the base end portion 33.
Further, a locking protrusion 81 is formed on the connecting rod 8, and when the opening degree of the throttle valve 2 is at a predetermined position, the locking protrusion 81 is locked to a locking protrusion 16 formed in the housing recess 15 of the throttle body 1, thereby restricting the throttle valve 2 from further rotating in the closing direction.
Further, a return spring 9 is coupled between the front surface recess 15 of the throttle body 1 and the connecting rod 8, and a connecting rod spring 10 is coupled between the connecting rod 8 and the throttle gear 7, on the outer periphery of the throttle gear 7 at the base end portion 33 of the throttle shaft 3.
In particular, in the present embodiment, the connecting rod spring 10 is embedded and disposed in a recess 72 formed on the throttle body 1 side of the throttle gear 7.
In the present embodiment, the load of the link spring 10 in the thrust direction is set to be larger than the load of the return spring 9 in the thrust direction due to the difference in spring constant, and the return spring 9 is set to be in a state of being closely wound (or a minute gap) at the time of assembly or in a state of being closely wound (or a minute gap) in accordance with the rotational operation of the throttle shaft 3, and the link 8 is set to be movable in accordance with the rotational operation.
As shown in fig. 3 and 4, in the present embodiment having the above configuration, the lock projection 81 of the connecting rod 8 is locked to the lock projection 16 of the throttle body 1, so that the opening degree of the throttle valve 2 is at a predetermined position such as during idling operation, and at this time, the return spring 9 is in a state of close contact or having a minute gap. Further, since the link spring 10 is in a long state in which the elastic force at the time of initial setting is exerted and the load of the link spring 10 in the thrust direction is set to be larger than the return spring 9, the link 8 is in a state of being pressed to the side of the holder 5 by the load of the link spring 10 in the thrust direction.
When a throttle signal for operating the throttle valve 2 in the opening direction from the preset position is issued based on an operation by the driver, the electric actuator 6 is driven to transmit a driving force from the rotary shaft 61 to the throttle gear 7 via the reduction gear 62, and the throttle shaft 3 is rotated in a direction to fully open the throttle valve 2.
At this time, the return spring 9 provided between the throttle body 1 and the connecting rod 8 increases the number of turns and increases the contact height with the rotation of the connecting rod 8, thereby exerting the elastic force in the reverse direction.
Therefore, as the load of the return spring 9 in the thrust direction increases, the return spring 9 exerts an elastic force so as to pivot the throttle shaft 3 in the direction of closing the throttle valve 2, and the link 8 is contracted by the return spring 9 against the load of the link spring 10 in the thrust direction, and moves away from the holder 5 in the direction of the base end of the throttle shaft 3.
Further, when a signal for returning the throttle valve 2 to the preset position is transmitted to the electric actuator 6 again based on a driving stop operation by the driver or the like, the driving force from the electric actuator 6 is cut off, and the throttle shaft 3 is rotated in the direction for closing the throttle valve 2 to the preset position by the returning force when the return spring 9 is returned from the extended state to the original state of being tightly wound, but in the present embodiment, the return spring 9 is allowed to be in close contact with the link 8 and the return spring 9 by the load force of the link spring 10 in the thrust direction in an appropriate low load state, and thus the return spring 9 can be prevented from being damaged by resonance.
In the present embodiment, the link spring 10 is housed in the recess 72 formed in the throttle gear 7, and the length of the return spring 9 in the axial direction is shortened on the outer periphery of the throttle gear 7, so that it is possible to achieve downsizing and use a spring having a lower spring constant as the return spring 9.
Further, in the present embodiment, since the return spring 9 is formed of a spring having a low spring constant, as shown in fig. 5, even when a member having high pressure resistance is used as the seal member 4, as compared with the above-described conventional example in fig. 6, the torque of the seal member 4 does not increase in the opening direction and the torque does not decrease in the closing direction, that is, the seal member 4 can be optimally set to achieve the following conditions: the electric current of the electric actuator 6 does not increase with the torque of the throttle shaft 3 when the throttle valve 2 is operated in the opening direction, and the life of the electric actuator 6 does not decrease; and no speed delay or return failure occurs when the throttle valve 2 is operated in the closing direction (return direction).