Load adjustment device

In a throttle-valve connection (1), two intake channels (2, 3) are provided alongside of each other, each having a throttle valve (4, 5). The two throttle valve (4, 5) are driven by separate setting motors (17, 18). The setting shaft (6, 7) of the throttle valve (4, 5) are connected to each other by an entrainment connection (8) which has play. Sliding clutches (9, 10) permit rotation of the throttle valve (6, 7) in the direction towards idling even if the gearing (11, 12) or setting motor (17, 18) is blocked.

FIELD AND BACKGROUND OF THE INVENTION 
The present invention relates to a load adjustment device having a throttle 
valve which is arranged in an air and fuel intake channel of an internal 
combustion engine, and wherein a setting shaft of the device is actuated 
by a setting motor. 
Load adjustment devices of this type have been frequently used recently 
instead of mechanical load adjustment devices in which the accelerator 
pedal of a motor vehicle is connected via a rod or cable with the throttle 
valve of the engine. Electrical transfer of the movement of the 
accelerator pedal to the throttle valve has a number of advantages over 
mechanical transfer; in particular, the laying of electric transmission 
lines is substantially less expensive than the providing of a mechanical 
transmission device. For reasons of safety, however, one does not dispense 
completely with the mechanical transmission device but provides, in 
addition, a so-called emergency actuation device having play so that, in 
the event of the failure of the electric device, mechanical actuation of 
the throttle valve is possible after overcoming the play. This additional 
mechanical emergency actuation device which is provided for reasons of 
redundancy naturally considerably increases the cost of such a load 
adjustment device. 
SUMMARY OF THE INVENTION 
It is an object of the invention so to develop a load adjustment device of 
the aforementioned type at the lowest possible expense and in such a 
manner that actuation is still possible even in the event of the failure 
of critical components. 
According to the invention there is provided, parallel to the air and fuel 
intake channel (2) of the engine, a second intake channel (3) having a 
further throttle valve (5), the setting device of the second throttle 
valve (5) being also driven by a setting motor (18). Both throttle valves 
(4, 5) are arranged completely swingably in the intake channel (2, 3), 
there being two setting shafts (6, 7) which are connected to each other by 
an entrainment connection (8) which is provided wit play. 
By this division of the stream of air over two intake channels, each having 
a throttle valve, and by the provision of a total of two setting motors, a 
high degree of redundancy is obtained at very low cost. Since a total of 
two setting motors are provided, should one setting motor fail, the other 
can still move the throttle valve associated with the setting motor which 
has failed into closed position; this occurs in the manner that the 
throttle valve which is still functional is swung out beyond the play of 
the entrainment device and thereby carries the other throttle valve along. 
Since the entrainment connection has play, after a setting back of the 
throttle valve having the defective drive, normal operation of the other 
throttle valve is possible with normal setting forces. With only one 
throttle valve functioning, a motor vehicle can be operated in normal 
manner in the partial-load range with all the control functions with which 
the system is provided. Only the upper full-load region is no longer 
obtainable. 
Due to the invention, no return springs or uncoupling springs are necessary 
for the load adjustment device, so that the opposing forces on the 
accelerator pedal are less and can be determined better. Another advantage 
of the entrainment connection with play is that each throttle valve can be 
adjusted over its setting range independently of the other and that, only 
after this play has been overcome, does coupling wIth the other throttle 
valve take place. 
One particularly advantageous embodiment of the invention provides that the 
setting motors (17, 18) are developed as stepping motors. The provision of 
stepping motors has the advantage that expensive feedback potentiometers 
for the throttle valves and thus also the expensive laying of feedback 
lines can be dispensed with. It is sufficient if a simple switch produces 
a signal when throttle valve is closed so that, upon actuation of the 
accelerator pedal, the zero position can be noted. Another advantage of 
stepping motors is that they have small commutators so that a problem 
resulting from oscillations of carbon brushes which lift-off a commutator 
does not occur. 
The load adjustment device is particularly compact if, in accordance with 
another embodiment of the inventIon, the setting motors (17, 18) are 
arranged as mirror images to each other above or below the two intake 
channels (2, 3) and are connected to the corresponding setting shaft (6, 
7) via, in each case, a gearing (11, 12) arranged laterally of the 
corresponding intake channel (2, 3). 
It is advantageous if, in each case, a sliding clutch which permits limited 
rotary movement is provided between the gearing (11, 12) and the 
associated setting shaft (6). In this way, emergency actuation is possible 
even if the gearing is blocked as the result of a defect. The limiting of 
the maximum possible relative movements of the two sliding clutches is 
necessary so that, via the sliding clutch of the side which is driving at 
the time, the setting shaft of the other side can be turned, by rotation 
of the other sliding clutch, to such an extent that the corresponding 
throttle valve comes into closed position. In the case of the load 
adjustment device of the invention, the defective throttle valve is set 
back against the force of the sliding clutch associated with it but then, 
due to the play of the entrainment device, regulates the functioning 
throttle valve without opposing frictional force. 
Another very advantageous development of the invention is that the play of 
the entrainment connection (8), in the case of throttle valves (4, 5) 
directed in the same direction, towards both sides amounts in each case to 
about 90 degrees and the two sliding clutches (10, 11) are so designed 
that they engage in form-locking manner after a relative rotation of 90 
degrees. By this fixing of the play at 90 degrees, a complete actuation of 
the throttle valve which is still intact is possible without the 
frictional force of a sliding clutch opposing this. 
The idling performance of the load adjustment device can be adjusted with 
particular sensitivity if the load adjustment device has a control device 
for actuating only one setting motor (17 or 18) for idling adjustment and 
for synchronous actuation of both throttle valves (17, 18) in operation 
under load. 
A failure of a throttle-valve drive can be noted in simple manner if both 
setting shafts (6, 7) have associated with them a safety switch contact 
(19, 20) for monItoring rotary movement of the corresponding setting shaft 
(6, 7). 
The load adjustment device is particularly simple from a structural 
standpoint if, in accordance with another embodiment of the invention, the 
entrainment connection (8) is formed by a sector-shaped projection (24) in 
the end surface of one adjustment shaft (7) and a sector-shaped projection 
(23) arranged above same in a facing end surface of the other adjustment 
shaft (7). 
The sliding clutches are developed particularly simply if each sliding 
clutch is provided, for limiting the maximum possible relative movement, 
with a pin (25) which is passed radially through the corresponding 
adjustment shaft and two stop segments (26, 27) on the corresponding gear 
wheel (13B). 
The interposing in each case of a gear between the corresponding setting 
motor and the corresponding setting shaft can be dispensed with if the 
setting motors (17, 18) are arranged, without the interpositioning of a 
gear, directly on the setting shafts (6, 7) of the throttle valves (4, 5). 
The setting shafts can, in this case, extend in alignment with each other 
so that the entrainment connection explained above can be used. 
It is also possible for the setting shafts (6, 7) to extend parallel to 
each other and that, in order to form the entrainment connection (8) on 
each setting shaft (6, 7) in radial alignment, a setting segment (29, 30) 
having a slot (31, 32) in the form of a circular arc is provided, into 
which a coupling rod (33) which connects the setting segments (29, 30) to 
each other engages. With such an embodiment, the sliding clutches can be 
dispensed with. The entrainment connection, on its part, is of very simple 
construction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a throttle-valve connection 1 which has two parallel-extending 
intake channels 2, 3 for directing air and fuel into an engine (indicated 
diagrammatically), each channel having a throttle valve 4, 5. The two 
throttle valves 4, 5 are arranged individually on horizontally arranged 
setting shafts 6, 7, the two shafts being aligned with each other and 
coupled to each other by an entrainment connection 8 which has play. Both 
setting shafts 6, 7 are extended laterally out of the throttle-valve 
connection 1 and connected there with a gearing 11, 12 by means of a 
sliding clutch 9, 10. Each gearing 11, 12 consists of three gear wheels 
13, 14, 15 which mesh with each other, the gear wheel 15 being arranged 
fixed for rotation on a driven shaft 16 of a setting motor 17 developed as 
stepping motor. A second setting motor 18, which is also developed as 
stepping motor, is arranged as a mirror image to the first setting motor 
17 on the top of the throttle-valve connection 1 and drives the setting 
shaft 7 in the same manner, via the gearing 12. A motor controller 
(indicated diagrammatically) is responsive to the position of an 
accelerator pedal (not shown) of the motor vehicle for electrically 
activating the motors 17 and 18 during conditions of power demand and idle 
of the engine. 
As also shown in FIG. 1, each setting shaft 6, 7 has a safety switch 
contact 19, 20 associated with it, said contact 19, 20 being connected 
electrically to and setting off a warning device 21, 22 when the setting 
motor 17, 18 is under current but the setting shaft 6, 7 is not rotating. 
FIGS. 2 and 3 show the development of the entrainment connection 8 in 
greater detail. Each of the end surfaces facing each other of the two 
setting shafts 6, 7 has a sector-shaped projection 23, 24. These 
projections comprise, in each case, an angle of 90 degrees, so that there 
remains between them also an angle of 90 degrees, as indicated in FIG. 3. 
If the throttle valves 4, 5 move in synchronism, then the projections 23, 
24 lie opposite each other. If, for instance, the throttle valve 4 stops 
as the result of a defect, then the right throttle valve 5 can be swung 
unimpeded up to 90 degrees. The normal actuation of the right-hand 
throttle valve 5 would in such a case in no way be interfered with by the 
left throttle valve 4 which has failed. If the left throttle valve 4 has 
failed in open position, then the right throttle valve 5 can be swung by 
motor through an angle of 90 degrees, in which case, after an angle of 
swing of 90 degrees, the entrainment connection 8 carries the left 
throttle valve 4 along with it so that the latter can be closed. In this 
case, there is relative movement in the sliding clutch 9. After repair of 
the load adjustment device, this turning of the sliding clutch must be 
reset. 
FIGS. 4 and 5 show the development of the sliding clutch 12. It can be seen 
that the gear wheel 13b is connected by friction lock to the setting shaft 
7 via a cup spring 28. A pin 25 extends radially through the setting shaft 
7. The gear wheel 13b is capable of coming against the pin 25 by means of 
the stop segments 26, 27 shown in FIG. 5 upon rotation in clockwise 
direction so that the setting shaft 7 is entrained in form-locked manner. 
If the gear wheel 13b turns in counterclockwise direction and if the 
setting shaft 7 is sufficiently sluggish, then there is relative movement 
between the gear wheel 13b and the setting shaft 7 until, in each case, 
the other side of the stop segment 26, 27 comes against the pin 25 and 
then carries the setting shaft 7 along with it. Since both gears 11, 12 
have such a sliding clutch 9, 10, the throttle valve which is no longer 
functional can be moved into closed position upon the blocking of a 
gearing 11, 12 via the other gearing, based on a sliding slide clutch. 
In the embodiment shown in FIGS. 6 and 7, parts functionally identical to 
the preceding figures have been provided with the same reference numbers. 
In this embodiment, the setting shafts 6, 7 are not aligned axially but 
extend parallel to each other. Each setting shaft 6, 7 is driven in each 
case directly by a setting motor 17, 18. The entrainment connection 8 is 
again so developed that both throttle valves 4, 5 can swing independently 
of each other up to a maximum of about 90 degrees. Upon further swinging, 
the other throttle valve 4 or 5, as the case may be, is carried along by 
the entrainment connection 8. 
The construction of the entrainment connection 8 can be noted from FIG. 7. 
On each setting shaft 6, 7 it has a setting plate or segment 29, 30 with, 
in each case, a slot 31, 32 of arcuate shape. The ends of a coupling rod 
33 engage in corresponding ends of the slots 31, 32. In the closed 
position of the throttle valves 4 and 5 shown, the coupling rod 33 lies, 
in each case, against a left-hand limitation of the corresponding slot 31, 
32. If, for example, the right-hand throttle valve 5 can no longer be 
actuated by the associated setting motor 18, then the right-hand throttle 
valve 5, after a swinging of the left-hand throttle valve 4 by 90 degrees, 
is carried along by the coupling rod 33 so that it can be moved into 
closed position.