US3905345A

US3905345A - Choke assembly for internal combustion engines

Info

Publication number: US3905345A
Application number: US426125A
Authority: US
Inventors: Masahiko Nakada; Hirofumi Matsumoto
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 1973-02-12
Filing date: 1973-12-19
Publication date: 1975-09-16
Anticipated expiration: 1992-09-16
Also published as: AU6386573A; JPS49104032A; AU473696B2; JPS5227769B2

Abstract

A choke valve regulator means for internal combustion engines is provided with a diaphragm box containing a diaphragm arranged capable of opening or closing the choke valve. The diaphragm box is connected to a source of vacuum by a suction conduit having a check valve and a orifice. A by-pass passage to allow air to enter the diaphram box is connected to the suction conduit and the by-pass passage is controlled by a solenoid switch valve so that the diaphragm will be operated to open the choke valve when the engine is warmed up and the vehicle reaches a certain speed.

Description

[451 Sept. 16, 1975 1 CHOKE ASSEMBLY FOR INTERNAL COMBUSTION ENGINES [75] Inventors: Masahiko Nakada; Hirofumi Matsumoto, both of Toyota, Japan [73] Assignee: Toyota Jidosha Kogyo Kabushiki Kaisha, Toyota, Japan [22] Filed: Dec. 19, 1973 [21] Appl. No.: 426,125

2/1974 Masaki et a1. 123/119 F 3/1974 Griese 123/119 F Primary ExaminerCharles J. Myhre Assistant ExaminerSheldon Richter Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [5 7] ABSTRACT A choke valve regulator means for internal combustion engines is provided with a diaphragm box containing a diaphragm arranged capable of opening or closing the choke valve. The diaphragm box is connected to a source of vacuum by a suction conduit having a check valve and a orifice. A by-pass passage to allow air to enter the diaphram box is connected to the suction conduit and the by-pass passage is controlled by a solenoid switch valve so that the diaphragm will be operated to open the choke valve when the engine is warmed up and the vehicle reaches a certain speed.

4 Claims, 1 Drawing Figure PATENTED SEP 1 61975 CHOKE ASSEMBLY FOR INTERNAL COMBUSTION ENGINES BACKGROUND oF THE INVENTION 1. Field of the Invention This invention relates to a choke valve regulator device for internal combustion engines and more particularly to a choke assembly which permits effective control of the exhaust gases without sacrificing engine idling stability or drive ability at low speed ranges.

2. Description of the Prior Art Generally, for operation of a cold engine which is not yet warmed up, a richer mixture of fuel is required than in the operation of a warmed-up engine because there is an insufficient vaporization of the fuel. The degree of mixing of the fuel and air also varies according to the various operating conditions of the engine, such as during starting, idling, constant-speed running, acceleration, etc., and also according to the degree of warm-up of the engine. In the past, various types of automatic chokes employing bimetals heated by the exhaust gas or by electric heaters have been used. However, recently great improvements have been made in warming up the engine which have alleviated the necessity of the choke valve. On the other hand, the noxious exhaust gases such as carbon monoxide, CO, or hydrocarbons, HC, discharged from the engine are produced in greater amounts when the engine has not been warmed up. It is desired, therefore, to open the choke valve promptly after the engine has been warmed up to a certain degree.

SUMMARY OF THE INVENTION This invention relates to a choke assembly capable of closing the choke valve at starting, idling, or low-speed running and to open the choke valve promptly when the engine has been warmed up more than a certain extent and once normal running has been commenced, thereby minimizing the discharge of the noxious exhaust gases.

BRIEF DESCRIPTION OF THE DRAWINGS;

The drawing is a schematic arrangement of a choke assembly according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention is now described in detail by way of an embodiment thereof with reference to the accompanying drawing.

Reference numeral 1 designates acarburetor having a venturi tube 2, a throttle valve 3 and a choke valve 4. The choke valve 4 is provided with a known regulator mechanism (not shown) and a revolving shaft 7. An intake manifold 5 has a water jacket 6. Secured to the revolving shaft 7 of the choke is a switch lever 8 formed with an elongated slot 9 in which fits one end of a link 10 with the other end of the link 10 being secured to a diaphragm 11 which divides diaphragm box 12 into two chambers. Spring 13 is positioned against diaphragm 11 in one of the chambers 14 in the diaphragm box 12. A negative pressure conduit 15 is provided connecting the diaphragm chamber 14 and the intake manifold 5 while a orifice 16 with a check valve 17 are provided within this conduit 15. By-pass pipe 18 connects the vacuum conduit 15 to the atmosphere as, for example, at the atmospheric side of the choke valve 4.

A solenoid valve 19 is placed within-theby-pass pipe 18 Additional elements include a battery ,20 and a temperature responsive switch 21 which is actuated when the water temperature in the water jacket 6 rises up over a certain level, such as 20 to;30C. A vehicle speed responsive switch 22 is actuated when the vehicle speed exceeds a certain valve such as 10 to.20 km/h. The-exciting coil of the solenoid valve 19, the battery 20, the water jacket temperature. responsive switch 21, and the vehicle speed responsive switch ,22 are all connected in series.-The water jacket temperature responsive switch 21 may be substituted by another type of thermal switch such as the type which is actuated in response to the lubricating oil temperature or the intake manifold wall temperature; Similarly, the vehicle speed responsive switch 22v may be replaced with a switch operable to detect the engine speed, the throttle opening, or other similar engine operating conditions. a f

The above-described apparatus of the present invention operates as follows. In the situation where the engine is not yet warmed up such that the cooling water temperature is low, or when the vehicle speed is low, both temperature responsive switch 21 and vehicle speed responsive switch 22 remain off. The solenoid valve 19 is not excited so the bypass pipe 18 is open to allow the atmospheric air to flow into the diaphragm chamber 14 through the combination of the by-pass pipe 18, the solenoid valve 19 and the vacuum conduit 15. This keeps both sides of the diaphragm 11 at a substantially equal pressure, and thus the link 10 remains inoperative. The opening of the choke valve 4 is then adjusted by a known choke valve regulator mechanism (not shown). Since the link 10 fits loosely within slot 9 in the lever 8, the link will not obstruct the movement of the choke valve 4. Although some of the air introduced through the by-pass pipe 18 flows into the intake manifold 5 by passing through the orifice 16, the check valve 17 and the vacuum conduit 15, this air is such a small amount that it will not produce any adverse effect on the engine performance.

When the engine is warmed up to the required certain extent, the cooling water temperature will have increased, and when the vehicle is running at a high speed, both the temperature responsive switch 21 and the vehicle speed responsive switch 22 will be turned on so that the exciting coil of the solenoid valve 19 becomes energized to close the by-pass pipe 18. As a result, the vacuum of the intake manifold 5 is transmitted to the diaphragm chamber 14 through the vacuum conduit 15 to let the diaphragm 11 move to the left as shown in the drawing against the pressure of spring 13, whereby the choke valve 4 is opened full by means of the link 10 and the lever 8. In this case, once a high negative pressure is applied into the diaphragm chamber 14, as long as the solenoid valve 19 is not opened, the high negative pressure continues to be applied into the diaphragm chamber 14 by the action of the check valve 17 to keep the choke valve 4 in the full opened position even if the vacuum in the intake manifold should be lowered thereafter by, for example, a fullthrottle acceleration. Thus, when the cooling water temperature is above a certain level, i.e., when the engine is warmed up to the certain extent, and when the vehicle speed is above a certain value, the choke valve 4 is opened fully to keep the discharge of the noxious exhaust gases to a minimum.

Also, according to the present invention, even when high speed running is performed in the cold and the conventional bimetal for the choke valve is being cooled by the cold air, the choke valve will not be closed if the engine is in a warmed up condition and the vehicle speed is over a certain level.

What is claimed is:

l. A choke assembly for internal combustion engines having an intake manifold comprising a choke valve, a diaphragm box with a switch lever, a diaphragm within said diaphragm box dividing said diaphragm box into two chambers and connected to said switch lever of said choke valve,-a vacuum conduit connecting one of the chambers in said diaphragm box with the intake manifold, a check valve and throttle mechanism provided in said vacuum conduit, a by-pass pipe connected to said vacuum conduit between said one of the chambers and said check valve and throttle mechanism and establishing a conduit to atmosphere, a solenoid valve with an exciting coil provided in said by-pass pipe, a temperature responsive switch for detecting the degree of warm-up-of the engine and a vehicle speed responsive switch, both 'of'the responsiveswitches being connected in series to said exciting 'coil of said solenoid valve, wherein when the vehicle speed and warming up of the engine have each exceeded a certain level, the by-pass pipe is closed byisaid solenoid valve to open the choke valve.

2. choke assembly according to claim 1, wherein a spring is positioned in said one of the chambers between said diaphragm'box and said diaphragm to urge said diaphragm toward the switch lever of said choke valve.

3. A choke assembly according to claim 1, wherein said temperature responsive switch for detecting the degree of warm-up measures the water temperature in a water jacekt for the intake manifold.

4. A choke assembly according to claim 1, wherein said check valve comprises a movable sealing means in the vacuum conduit which maintains in one of the chambers in said diaphragm box the highest vacuum produced in the intake manifold when the by-pass pipe is closed by said solenoid valve.

Claims

1. A choke assembly for internal combustion engines having an intake manifold comprising a choke valve, a diaphragm box with a switch lever, a diaphragm within said diaphragm box dividing said diaphragm box into two chambers and connected to said switch lever of said choke valve, a vacuum conduit connecting one of the chambers in said diaphragm box with the intake manifold, a check valve and throttle mechanism provided in said vacuum conduit, a by-pass pipe connected to said vacuum conduit between said one of the chambers and said check valve and throttle mechanism and establishing a conduit to atmosphere, a solenoid valve with an exciting coil provided in said by-pass pipe, a temperature responsive switch for detecting the degree of warm-up of the engine and a vehicle speed responsive switch, both of the responsive switches being connected in series to said exciting coil of said solenoid valve, wherein when the vehicle speed and warming up of the engine have each exceeded a certain level, the by-pass pipe is closed by said solenoid valve to open the choke valve.

2. A choke assembly according to claim 1, wherein a spring is positioned in said one of the chambers between said diaphragm box and said diaphragm to urge said diaphragm toward the switch lever of said choke valve.