Electricity: motive power systems – Switched reluctance motor commutation control
Reexamination Certificate
2001-02-08
2003-11-11
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Switched reluctance motor commutation control
C251S129110, C251S305000, C123S336000, C123S337000, C123S399000
Reexamination Certificate
active
06646395
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a throttle body, which has at least one housing, a stub pipe arranged in the housing and accommodating a throttle butterfly, and an actuator, which drives the throttle butterfly.
A throttle body of this kind is known from EP 0 337 099 A2, which describes a device for controlling the power of an internal combustion engine provided for the purpose of driving vehicles. Here, the throttle body has a housing in which a positioning motor designed as an electric motor is arranged. Via transmission elements, such as a reduction gear, the actuator drives a moving element, which is a throttle butterfly for controlling the power of the internal combustion engine. However, the production of the device known from EP 0 337 099 A2 requires a particularly high outlay on production and assembly owing to the large number of parts to be produced and assembled.
In the case of a throttle body with an actuator, heat generated in the actuator during the operation of the actuator can lead to particularly severe heating of the components of the actuator. However, an actuator operated subject to continuous particularly severe heating is generally prone to faults and has a particularly short life. A particularly short life of the actuator, in turn, is associated with a particularly high outlay on the maintenance and repair of the throttle body, leading to extremely high costs for the operation of the throttle body.
SUMMARY OF THE INVENTION
The object on which the invention is based is therefore to indicate a throttle body of the above-mentioned type with which the outlay on production and assembly is particularly low while, at the same time, particularly severe heating of the actuator is reliably avoided.
According to the invention, this object is achieved by virtue of the fact that the housing is composed of plastic, and functional elements of the actuator are arranged in the housing and are at least partially surrounded by plastic, the throttle butterfly being surrounded by a heat-conducting stub pipe, a functional element of the actuator and the heat-conducting stub pipe being connected to one another in a heat-conducting manner or being of one-piece design.
The invention starts from the consideration that a throttle body that involves a particularly low outlay on production and assembly should have a particularly small number of parts. The number of parts to be assembled is particularly small if there is no need for a separate housing for the actuator and if it is possible to integrate functional elements of the actuator into the housing of the actuator. At the same time, it should be possible to adapt the housing to the spatial dimensions of the functional elements of the actuator in a particularly simple manner. For this purpose, the housing of the throttle body is manufactured from plastic, the housing of the throttle body being designed both as the housing of the throttle body and as the housing of the actuator.
In this arrangement, particularly severe heating of the actuator is reliably avoided if the heat generated in the actuator can be dissipated from the actuator during the operation of the actuator. However, the plastic housing of the throttle body and of the actuator proves unsuitable as a heat dissipation element since the housing of the throttle body and of the actuator should not heat up to a particularly great extent if the actuator is to function in a particularly reliable manner. The actuator should therefore have connected to it a heat conductor, via which the heat generated in the actuator can be dissipated from the actuator and the housing of the throttle body and of the actuator during the operation of the actuator. An additional component of the throttle body can be dispensed with here if a part that is provided in the throttle body in any case can be used as a heat conductor. For this purpose, a functional element of the actuator is connected in a heat-conducting manner to a stub pipe surrounding the throttle butterfly.
It is advantageous if the functional element of the actuator and the stub pipe are in direct contact with one another at at least one point. This ensures direct heat transfer from the functional element of the actuator to the stub pipe, as a result of which the throttle body has a particularly simple construction that has a particularly low susceptibility to faults. To compensate for inaccuracies of fit and for a particularly pronounced thermal conductivity, the connection between the two elements can be assisted by means of thermally conductive paste, for example.
It is advantageous if the stub pipe is composed essentially of metal. Metal is a particularly good heat conductor, ensuring particularly reliable dissipation of the heat generated in the actuator during the operation of the actuator. It is advantageous here if the stub pipe is composed essentially of aluminum. Components made of aluminum can be manufactured with a high accuracy of fit in a particularly simple manner, and the outlay required for the production of the throttle body is therefore particularly low. Moreover, aluminum is intrinsically particularly light, allowing the weight of the throttle body to be reduced to a particularly low level.
The heat absorbed by the stub pipe during the operation of the actuator is removed from the throttle body by the air flowing through the stub pipe. This is a particularly reliable way of avoiding heating of the actuator during the operation of the actuator.
It is advantageous if the stub pipe and the functional element of the actuator have means by which the stub pipe and the functional element of the actuator can be positioned relative to one another. It is advantageous if the means are domes. The word “domes” is used to denote form-locking joints by means of which a first component can be positioned relative to a second component. By virtue of these means, the outlay required for assembly in the production of the throttle body can be reduced to a particularly low level since the stub pipe and the functional element of the actuator can be connected to one another in a particularly simple manner, this being associated with particularly short assembly times for the throttle body. Moreover, this is a reliable way of avoiding inaccuracies of fit, caused by manufacturing tolerances, when joining the stub pipe and the functional element of the actuator together, and as a result the throttle body takes up a particularly small amount of space.
It is advantageous if the means by which the stub pipe and the functional element of the actuator can be positioned relative to one another can be produced both in one piece with the stub pipe and in one piece with the functional element of the actuator of the throttle body. This simplifies the production of the throttle body since there is no need for the additional process of fitting the respective domes. As an alternative or in addition, the means can be connecting elements, e.g. rivets, nails or screws, which can be secured both on the stub pipe and on the functional element of the actuator. As an alternative or in addition, it is furthermore also possible to make provision for the housing of the actuator and the stub pipe to be pressed against one another.
The housing can advantageously be manufactured from plastic by injection molding. An injection-molded housing allows the shape of the housing to be adapted in a particularly simple manner to different designs of the housing of the throttle body through the design of the injection mold. Moreover, the requisite functional elements of the actuator can be integrated into the housing in a particularly simple manner during the production of the latter. For this purpose, the functional elements are first of all placed in the injection mold. The functional elements are then sealed off from the injection mold at the points at which they are not to be surrounded by plastic, and the injection mold is then filled with plastic. In addition, further elements of the throttle body, such as bearings, electrical connection
Farber Martin A.
Mannesmann VDO AG
Miller Patrick
Nappi Robert E.
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