Fluid handling – With indicator – register – recorder – alarm or inspection means – Position or extent of motion indicator
Reexamination Certificate
2001-09-06
2003-01-14
Chambers, A. Michael (Department: 3753)
Fluid handling
With indicator, register, recorder, alarm or inspection means
Position or extent of motion indicator
C251S148000, C251S305000, C305S123000, C123S337000, C123S399000
Reexamination Certificate
active
06505643
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a throttle valve body, especially for an internal combustion engine of a motor vehicle, having a tubular body, which comprises at least an outer casing, an inner casing, a first end face and a second end face, the inner casing forming a flow duct through which a gaseous medium can flow in a main flow direction, a throttle plate fixed to a throttle shaft being swivel-mounted in the flow duct.
Throttle valve bodies are generally used to control the fresh charge quantity of a motor vehicle. Throttle valve bodies comprise a housing with a flow duct and a throttle member arranged in the flow duct. The throttle member assumes a certain position in the flow duct for the admission of a specific fresh charge quantity. For this purpose the throttle member may be mechanically or electronically actuated.
Housings of throttle valve bodies are usually manufactured from plastic or metal. Throttle valve body housings that are made of metal, such as aluminum, can be produced with especial accuracy and may therefore have especially fine tolerances. Fine tolerances are required for a throttle valve body in the area of the throttle plate especially where it is intended that just a very slight movement of the throttle plate should be capable of influencing the quantity of medium flowing through the flow duct of the throttle valve body. In the closing area of the throttle plate these requirements are also termed leakage air requirements.
Metal housings of throttle valve bodies have the disadvantage, however, that after manufacturing of the housing by the die-casting process, for example, expensive finishing of the housing is generally required. Finishing of aluminum housings is necessary, for example, in order to meet the proposed functional requirements in and on the housing. Functional requirements relate, in particular, to the flow duct, the accommodation for the actuator and gear mechanism center distances. Accurate machining of the bearing seats is generally also necessary, since the correct operating clearance (bearing internal clearance) is achieved only by the press fit on the needle-roller bearing.
Throttle valve body housings made of plastic have a lower weight than throttle valve body housings essentially made of metal, such as aluminum. Furthermore, as a material plastic is particularly easy to adapt to widely varying geometric configurations of the housing. In the case of plastic housings manufactured by the injection molding process, inserts such as bearings for supporting the throttle shaft can also be molded into the housing.
Throttle valve body housings made of plastic by the injection molding process have the disadvantage, however, that they shrink during and after the injection molding process. In addition, housings of this type may distort after removal from the mold, that is to say they become deformed when they are taken out of the injection mold. Nor are the dimensions of throttle valve body housings made of plastic particularly stable over an especially wide temperature range. On the one hand throttle valve body housings in a motor vehicle are exposed to outdoor temperatures as low as −40° C. On the other hand, in the operation of the throttle valve body the temperature of the throttle valve body may rise to more than 100° C. These large temperature fluctuations may lead to detrimental deformations of the plastic in the throttle plate swivel area. These deformations can in turn lead over time to a reduction of the especially high fitting accuracy of the throttle plate in the housing. In this case especially high fitting accuracy means, for example, fitting accuracies of the housing of the throttle valve body in the range from 0 to 30 &mgr;m, where the housing is subject to the ISO tolerance in respect of the dimension of the flow duct, for example. As a result of changes in the shape of the flow duct, the especially high leakage air requirements can no longer be met, particularly when the throttle is in the idle position. Associated with this are an increased fuel consumption and a reduced exhaust emission quality. Dimensional stability of the throttle valve body housing, especially the flow duct, over a number of years is therefore necessary for a constant fuel consumption and constant exhaust emission quality.
SUMMARY OF THE INVENTION
The object of the invention is therefore to specify a throttle valve body of the aforementioned type, which has an especially low weight and is especially inexpensive to manufacture and the flow duct of which has an especially high dimensional stability under especially high thermal loads. In addition the throttle valve body should be particularly easy to adapt to different installation conditions.
According to the invention this object is achieved in that the outer casing of the tubular body is at least partially enclosed by a plastic housing, at least one actuator for the throttle shaft being arranged in the housing and the tubular body being largely composed of metal.
The invention proceeds on the premise that a throttle valve body, which has an especially low weight and is especially inexpensive to manufacture, the flow duct of the throttle valve body at the same time having an especially high degree of dimensional stability, even under especially high thermal loads, should have a flow duct, which is formed, at least in the area of the throttle plate, by a metal component. This is because metal proves to be particularly dimensionally stable even under especially high thermal loads. Furthermore, metal can generally be machined with more dimensional accuracy than plastic. In addition a metal component can guarantee an especially good thermal connection to electromechanical components such as the actuator of the throttle valve body. Nevertheless, in order to ensure particular ease of manufacture of the throttle valve body, the metal enclosing the flow duct should not require the usual expensive finishing work associated with a throttle valve body housing made of metal. For this reason only the flow duct should be formed from a component made of metal. For an especially low throttle valve body manufacturing cost, the flow duct of the throttle valve body might take the form of a standard metal component. A tubular body, which is available as a standard component, is suitable for this purpose.
In order at the same time to ensure an especially low manufacturing cost for the throttle valve body together with an especially low throttle valve body weight and particular ease of adaptation to different installation conditions, the other elements of the throttle valve body and the tubular body are encapsulated in injection-molded plastic in the manner of a housing. In the process, the plastic housing at least partially encloses the tubular body. The flow duct in this case is formed by the inner casing of the tubular body and is composed of metal. However, recesses or bores may be arranged in the inner casing of the tubular body, through which measuring instruments, for example, come into contact with the flow duct. Said recesses or bores may be sealed with plastic, in order to form a smooth inner casing with the inner casing of the tubular body so as to avoid swirling in the flow duct. The flow duct is then formed not completely but almost completely of metal.
The housing to be molded on can be adapted to specific installation conditions for different throttle valve bodies. The throttle valve body is therefore formed from a uniform standard component, the tubular body, and a differing, specifically adaptable element, the housing to be molded on to the tubular body.
At least the first end face of the tubular body is advantageously enclosed by plastic. The inner casing of the tubular body is thereby protected especially reliably, at least by the first end face, against contamination, which can get into the flow duct from outside.
The outer casing of the tubular body is advantageously enclosed radially all round by the housing. This arrangement of the housing on the tubular body is par
Oppermann Rolf
Scholten Lutz
Seeger Armin
Welteroth Peter
Chambers A. Michael
Farber Martin A.
Siemens AG
LandOfFree
Throttle valve body does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Throttle valve body, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Throttle valve body will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3041385