Rotary actuator

A device, in particular for controlling a throttle cross-section in an operating fluid carrying line of an internal combustion engine, has a housing provided with a bore and a throttle aperture, an inlet connecting piece associated with the housing, a rotary valve acting as a throttling organ and being centrally arranged so as to be rotatable in the housing and closing the throttle aperture to a greater or a lesser extent, so that a fluid to be controlled passes through the inlet connection piece directly via the throttle opening. The rotary valve has a shaft with an axis, and also has a control edge and a rear edge which is opposite to the control edge. The control edge and the rear edge both extend obliquely relative to the axis of the shaft of the rotary valve.

BACKGROUND OF THE INVENTION 
The present invention relates to a rotary actuator. More particularly, it 
relates to a rotary actuator for controlling a throttle cross-section in 
an operating fluid carrying line of an internal combustion engine, with a 
housing and an actuating motor which drives a rotary valve acting on a 
throttling organ. 
Rotary actuators of the above mentioned general type are known in the art. 
From the DE-GM 88 90 3181, such a rotary actuator is already known, which 
due to the forming of vortexes can however cause whistling noises, and its 
control behavior can be influenced by pulses of air turbulence occurring 
on its rotary valve. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a rotary 
actuator of the above mentioned type, which avoids the disadvantages of 
the prior art. 
In keeping with these objects and with others which will become apparent 
hereinafter, one feature of the present invention resides, briefly stated, 
in a rotary actuator in which the rotary valve has a control edge and 
opposite this, a rear edge both of which extend obliquely relative to an 
axis of a shaft of the rotary valve. 
When the rotary actuator is designed in accordance with the present 
invention, it has the advantage that on flowing through the disc valve, 
disturbing noises are avoided and air turbulences do not occur. Moreover, 
the air turbulences reduce to a small amount of the size of bearing 
friction. 
It is of particular advantage that the throttle opening, which is 
configured as an oblique window, has limits which extend obliquely in 
relation to the shaft axis. Due to both the output and the input 
connection piece being arranged at the side of the rotary actuator shaft, 
in particular such that the flow is guided approximately tangentially past 
the rotary disc valve shaft, the formation of vortexes in the valve 
housing is reduced, which has the additional effect of reducing noise. 
In accordance with another embodiment of the present invention, the rotary 
actuator has limiting edges of the throttle aperture which are allocated 
at the edges of the rotary valve and extend obliquely relative to the axis 
of the shaft of the rotary valve. 
Still another feature of the rotary actuator is that the axis of an input 
connection piece which is arranged on the rotary valve housing also moves 
laterally past the shaft of the rotary valve. 
In accordance with another feature of the present invention the throttle 
aperture can have the shape of a parallelogram or a rectangle. 
Finally, the rotary valve can be adjusted from its rear position in either 
direction of rotation. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A rotary actuator 1 for regulating the idle combustion air of an internal 
combustion engine has a rotary valve housing 2 with housing cap 3, within 
which an actuating motor 4 is accommodated. The actuating motor 4 has a 
rotor 5 acting on a rotary valve which serves as a throttle. The rotary 
valve 6 is connected to the rotor 5 via a shaft 7 which is supported in 
two anti-friction bearings 8, 9. The rotary valve 6 rests in a bore 11 
which is arranged parallel with the shaft 7 in the housing 2. In the 
region of the rotary valve 6, the housing 2 has at its side a throttle 
aperture 12 which terminates in the bore 11 and which is connected to an 
input connection piece 13 for the purpose of connecting a bypass line 14. 
The bypass line 14 leads to an induction pipe 15 with a throttle valve, 
for the control of the volume of combustion air to the internal combustion 
engine. The input connection piece 14 is located at right angles to the 
shaft 7, but its axis 16 is offset such that it extends past the side of 
shaft 7 of the rotary valve 6 and does not cut it. In the wall area 
opposite the throttle aperture 12, the bore 11 has an outlet opening 17, 
which in relation to the throttle aperture 12 has a larger cross-section 
and which is connected to an outlet connection piece 18. The axis 19 of 
the output connection piece 18 is located like that of the input 
connection piece 16, vertically in relation to the shaft 7, but laterally 
offset. The axes 16 and 19 are on the same center line. 
As shown in FIG. 2, the throttle aperture 12 has a rectangular shape. The 
longer limiting edges 21 of the throttle opening 12 are at an acute angle 
obliquely in relation to the axis of the shaft 7. Alternatively, the 
throttle aperture may be in the shape of a parallelogram, so that the 
longer limiting edges are again arranged obliquely in relation to the axis 
of the shaft 7 and the shorter edges approximately at right angles to it. 
The rotary valve 6 consists of a sleeve 23 which is connected to the shaft 
7 and on which a closing element 25 is fixed via two arms 24. The closing 
element is designed as a parallelogram shaped cutout of a cylindrical 
surface. The closing element has a front control edge 26, which sweeps the 
throttle aperture 12 to a greater or lesser extent and thereby determines 
the size of the opening gap 27 of the throttle aperture 12. The sharp 
edged control edge 26 extends like the limiting edges 21 of the throttle 
aperture 12, at an acute angle in relation to the axis of shaft 7. The 
rear edge 28 of the rotary valve 6 which lies opposite the control edge 
26, similarly extends obliquely relative to the axis of shaft 7. The 
limiting edges 21 of the throttle aperture 12, and the control edge 26 and 
the rear edge 28 of the rotary valve 6 are inclined to the same side, 
opposite the axis of the shaft 7. 
FIG. 2 shows the rotary valve 6 in its stationary position which it assumes 
when the actuating motor 4 is not energized. To regulate the idle air 
volume, the throttle aperture 12 can be completely closed by rotating the 
rotary valve 6 clockwise (position 30 of the closing element shown by a 
dot-dash line). Rotation in anti-clockwise direction will open the 
throttle aperture further (position 31 of the closing element shown in a 
dash-cross line). The opening gap 27 is obliquely arranged relative to the 
bore 11 and to the axis of the shaft 7 at any rotational position of the 
rotary valve 6. The oblique position of the throttle opening limiting 
edges 21 and of the edges 26, 28 of the closing element 25 is matched to 
the thickness of the shaft 7 or of the sleeve 23 in order to minimize 
whistling noise and air turbulence pulses. The rear oblique edge 28 in 
particular counteracts the forming of a vortex in that part of the bore 11 
through which there is no direct flow. The two constructions of the 
throttle aperture 12 have the following additional effects: the obliquely 
lying rectangular aperture has a slightly enlarged setting angle and with 
leakage air which is unchanged relative to the state of technology; the 
parallelogram shaped throttle aperture has an unchanged setting angle, but 
slightly increased leakage air. 
During operation of the rotary actuator 1, the actuating motor 4 receives a 
signal for the rotary setting of the rotor 5 from a control unit of the 
internal combustion engine. Corresponding to this rotary setting, the 
closing element 25 is then in relation to the throttle opening 12. 
Depending on the size of the developing opening gap 27, a greater or 
lesser air volume now flows through the input connection piece 13 into the 
rotary valve housing 2. The dot-dash flow lines 32 in FIG. 3 show that the 
lateral offset of the axes 16 and 19 of input and output connection pieces 
13 and 18 opposite shaft 7 result in a vortex-free throughflow of the 
rotary actuator housing 2, which depending on the throttle setting is 
restricted to a greater or lesser extent, but is otherwise largely in a 
straight line. The flow moves laterally past the shaft 7 to the output 
connection piece 18. The vortex-free throughflow is promoted by the 
arrangement of the throttle aperture 12 on the input connection piece 13 
and an outlet opening 17 which has a larger cross-section relative to the 
latter; this effect would not be achieved if the throttle opening were 
arranged on the outlet connection piece. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
constructions differing from the types described above. 
While the invention has been illustrated and described as embodied in a 
rotary actuator, it is not intended to be limited to the details shown, 
since various modifications and structural changes may be made without 
departing in any way from the spirit of the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.