Information
-
Patent Grant
-
6557523
-
Patent Number
6,557,523
-
Date Filed
Wednesday, July 5, 200024 years ago
-
Date Issued
Tuesday, May 6, 200321 years ago
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Inventors
-
Original Assignees
-
Examiners
- Wolfe; Willis R.
- Gimie; Mahmoud
-
CPC
-
US Classifications
Field of Search
US
- 123 337
- 123 361
- 123 399
- 029 89012
- 029 890126
- 251 305
-
International Classifications
-
Abstract
An electronic throttle control system with a plastic composite housing member and injection molded motor assembly. The motor assembly is preassembled with a gear shaft member to a metal mounting plate which in turn is injection molded into the composite housing member. A portion of the motor is secured to the electronic throttle control housing during the injection molding process. The distance between the gear shaft member and motor remains constant.
Description
TECHNICAL FIELD
This invention relates to electronic throttle control mechanisms for internal combustion engines.
BACKGROUND
Valve assemblies for engines and related systems typically utilize rotatable valve members in fluid flow passageways to assist in regulating fluid flow through them. For example, throttle valve members are positioned in air induction passageways for internal combustion engines. The valve assemblies are controlled either mechanically or electronically and utilize a mechanism which directly operates the valve member.
For consideration such as weight, cost, and ease of manufacturing, it is preferred to have the body, cover, and some of the component members or mechanisms made from plastic materials, such as plastic composite materials. However, these materials often can expand or contract in the temperature range extremes typically experienced in vehicle engine environments. Moreover, certain operational components, such as gear members and rotatable shaft members, should be accurately positioned at all times for optimum operations. Also, it is preferable for the motors for electronic throttle control systems to not be enclosed in composite housings due to the need to dissipate heat generated in the use of the systems.
It would be desirable to have an electronic valve control system with a plastic composite housing and cover member and which accurately maintains the operating components in position at all times. It also would be desirable to have an electronic valve control system with an injection molded housing which incorporates the motor in the molding process and still allows sufficient dissipation of generated heat.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved electronic valve control system which utilizes molded plastic composite materials and accurately maintains the position of operating components. It is a further object of the present invention to provide an improved electronic throttle control assembly in which the motor is injection molded as part of the housing.
In accordance with the present invention, a metal motor mounting plate is provided which is insert injection molded into the plastic composite material forming the housing. A gear shaft is mounted in the metal mounting plate so that it will be accurately positioned for use with the operational mechanism of the electronic throttle control system. The motor is attached to the mounting plate prior to the injection molding procedure, and the mold and injection molded materials only covers a portion of the motor. Shutoff areas in the mold prevent the injected plastic material from covering certain areas of the motor and gear shaft.
Other features and advantages of the present invention will become apparent from the following description of the invention, particularly when viewed in accordance with the accompanying drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
illustrates an electronic throttle control assembly in accordance with the present invention;
FIG. 2
illustrates the cover member of the mounting plate with a gear shaft and motor attached thereto in accordance with the present invention; and
FIG. 3
is an elevational view of the metal mounting plate and attached components as shown in FIG.
2
.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
FIGS. 1-3
illustrate a preferred embodiment of an electronic throttle control assembly in accordance with the present invention. The electronic throttle control assembly is generally indicated by the reference numeral
10
in FIG.
1
.
The electronic throttle control assembly
10
includes a housing or body member
12
and a cover member
14
. A cavity
13
is formed between the cover member and housing. The housing
12
includes a motor section
16
, throttle valve section
18
, and a gear train mechanism
20
. The cover member includes a throttle position sensor (TPS)
22
, together with related electronics, which reads or senses the position of the throttle valve and transmits it to the electronic control unit (ECU) of the vehicle. The cover member
14
also contains an electronic connector member (not shown) which connects the TPS to the electronic control unit and also supplies power to the electronic throttle control assembly.
A throttle valve
30
is positioned in an air flow passageway
32
in the body or housing member
12
. The throttle valve member
30
is connected to a throttle shaft member
34
by a plurality of fasteners
36
. One end
38
of the throttle shaft member protrudes through the body member and into the cavity formed between the cover member and the housing.
The gear train mechanism
20
is positioned in the cavity
13
between the housing or body member and inside the cover member. Gear member
40
, which is part of the gear train mechanism
20
, is attached to the throttle shaft member
34
. The gear train mechanism
20
also includes an idler gear member
42
and a spur gear member
44
. The intermediate or idler gear member
42
is attached to an idler shaft member
46
. The spur gear member is attached to the shaft
52
of the motor.
A motor
50
which has an outer housing or casing
51
and is secured to the housing member
12
and used to operate the gear train mechanism which in turn rotates the throttle valve shaft member
38
and positions the throttle valve member
30
at a desired position in the air flow passageway
32
. The motor
50
is connected to the shaft
52
on which the spur gear
44
is secured. In this manner, when the motor
50
is activated by the electronic control unit due to signals received from the operator of the vehicle, the position of the throttle valve member
30
in the air passageway is adjusted in order to allow the appropriate amount of air to enter into the engine and meet the requested demand. The position of the throttle valve member in the air flow passageway is sensed by the TPS and relayed or fed back to the ECU to confirm or adjust the desired throttle valve setting. The throttle valve thus regulates the air flow to the internal combustion engine and in turn the speed of the engine and velocity of the vehicle.
Spur gear
44
has a plurality of teeth
45
which mesh with the teeth
43
in adjacent idler gear
42
in the gear train mechanism
20
as mentioned above. The gear members
40
,
42
and
44
are preferably made from a plastic material, such as nylon, although they can be made of any other comparable material, or metal, which has equivalent durability and function. Also, the gear member
40
is preferably molded onto the end
38
of the throttle shaft member
34
in order to be firmly and permanently affixed to the shaft member.
The motor
50
is typically a DC motor and typically has a casing or outer shell member
51
made from an aluminum or metal material. Since typical automotive composite materials have difficulty dissipating the amount of heat generated by such motors, the motor preferably should not be enclosed in a composite housing. A metal motor mounting plate
60
is insert molded into the housing or body member
12
. The motor
50
via the motor casing
51
is attached to the mounting plate
60
. Also, the idler gear shaft member
46
is press fit into opening
62
in the mounting plate
60
.
With the present invention, the motor
50
, mounting plate
60
, and idler shaft member
46
are preassembled. The motor casing member
51
is fastened, welded or otherwise securely attached to the mounting plate
60
. The idler shaft member
46
is press fit into opening
62
in the mounting plate. The assembly is then insert molded into the plastic composite material forming the electronic throttle control housing
12
.
During the insert molding process, the motor
50
(with cover or casing
51
) is placed in an injection molding tool or die, such that when the mold halves are closed, certain areas around the motor and gear shaft are filled with composite material. Shutoff areas are utilized in the molding process to prevent the composite material from entering the motor gear
44
and motor electrical terminal area (not shown). These are shutoff zones or areas
64
,
66
, and
68
as shown in the drawings. As to shutoff area
64
, the motor housing is positioned in a tight tolerance fit into a cavity in the mold which prevents plastic from covering the rest of the motor. On shutoff area
66
, the shaft
46
is similarly positioned in a tight tolerance fit into another cavity in the mold which prevents plastic from covering the entire shaft. Finally, as to shutoff area
68
, the mold makes direct contact with the surface
69
of the motor and prevents plastic from filling the area around the gear
44
. In this manner, the mold around the casing
51
is limited to the portion
70
shown in
FIG. 1
, and the mold around gear shaft
46
is limited to the portion
71
also shown in FIG.
1
. This provides sufficient plastic material in order to firmly hold the motor
50
, gear shaft
46
, and mounting plate
60
in the housing
12
, but does not completely enclose the motor which would create heat dissipation difficulties. The plastic also does not completely cover all of the length of the gear shaft which allows the idler gear
42
to be mounted thereon and freely rotate.
A plurality of support rib members
72
, only one of which is shown, are utilized to add additional strength and reinforcement to the housing member and connection to the motor and motor casing.
The mounting plate
60
is preferably made from a metal material, such as steel, which has sufficient strength and durability for its intended use. Also, as shown in
FIG. 3
, the mounting plate
60
is formed with a plurality of holes or openings
80
at various portions thereof. The openings
80
are filled with plastic material during the molding process and help retain and secure the motor to the body member
12
.
With the idler shaft member
46
assembled as part of the motor assembly, the center-to-center distance
90
between the idle shaft member
46
and motor shaft member
52
remains fixed and constant throughout the life of the electronic throttle control mechanism. This is an advantage over other composite electronic throttle control housing designs which may have the idler shaft member molded into or press fit directly into the composite housing. In such designs, the center-to-center distance can change due to environmental conditions, such as humidity and temperature, that the electronic throttle control assemblies are exposed to during normal operation of vehicles.
While the invention has been described in connection with one or more embodiments, it is to be understood that the specific mechanisms and techniques which have been described are merely illustrative of the principles of the invention. Numerous modifications may be made to the methods and apparatus described without departing from the spirit and scope of the invention as defined by the appended claims.
Claims
- 1. An electronic throttle control assembly comprising:a housing made from a plastic composite material; a cover member positioned on said housing and forming a cavity therebetween; an air passageway in said housing; a throttle shaft rotatably positioned in said housing with one end extending through said air passageway and the other end extending into said cavity between said cover member and said housing; a mounting plate molded into said housing; a motor attached to said mounting plate before said mounting plate is molded into said housing, said motor being partially covered by said plastic composite material; and a gear shaft attached to said mounting plate and extending into said cavity.
- 2. The electronic throttle control assembly as recited in claim 1 further comprising a gear train mechanism comprising a first gear member attached to said motor, a second gear member positioned on said gear shaft, and a third gear member attached to said other and of said throttle shaft.
- 3. The electronic throttle control assembly as recited in claim 1 wherein said gear shaft is press fit into an opening in said mounting plate.
- 4. A method of manufacturing an electronic throttle control mechanism, said mechanism having a housing, a cover, a motor, gear train mechanism, and throttle valve member, said method comprising the steps of:forming an assembly of a motor, metal mounting plate, and gear shaft for the gear train mechanism, positioning said assembly into a mold; injecting plastic material into said mold to form said housing, said housing encapsulating said metal mounting plate, a portion of said gear shaft and a portion of said motor; positioning said gear train mechanism on said housing; and positioning said cover on said housing enclosing said gear train mechanism.
- 5. The method as recited in claim 4 further comprising the steps of positioning a throttle shaft member in said housing and attaching said gear train mechanism to said throttle shaft member.
US Referenced Citations (16)