GB1584997A

GB1584997A - Control devices for use in manually operated systems for remote position control using hydraulic transmission

Info

Publication number: GB1584997A
Application number: GB4016577A
Authority: GB
Original assignee: Cibie Projecteurs SA
Current assignee: Cibie Projecteurs SA
Priority date: 1976-10-05
Filing date: 1977-09-27
Publication date: 1981-02-18
Also published as: ES462772A2; YU39403B; DE2744232A1; SE7711112L; FR2366956B2; NL7710779A; DE2744232C2; BE858650R; AR213131A1; BR7706478A; YU237777A; FR2366956A2; RO75649A; SE425774B

Description

(54) CONTROL DEVICES FOR USE IN MANUALLY OPERATED SYSTEMS FOR REMOTE POSITION CONTROL USING HYDRAULIC TRANSMISSION (71) We, CIBIE PROJECTEURS, a Societe Anonyme organised under the laws of France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to control devices for use in manually-operated systems for remote position control using hydraulic transmission. One application for such systems is the adjustment of the attitude of vehicle head-lamps by the driver of the vehicle, without leaving his seat. In particular, the inclination of the axis of the headlamps to the horizontal may be adjusted in this way. Our Patent No. 1,469,421 illustrates a system which performs such a function.

The control device for such a system must include a manually-operable control element, and at least one mechanical-to-hydraulic transducer which is connected by some form of transmission mechanism to the control element. One type of transmission mechanism which has been proposed is a screw device; a screw with the usual, small, helix angle will be irreversible, that is, it will not be moved by forces exerted thereon by the transducers, but it will also have the disadvantage that a number of turns of the screw are needed to move the headlamps over their full range of movement. As far as accuracy of adjustment of the headlamps is concerned, it is not necessary to have such a large velocity ratio; also, it is not convenient for the driver of a vehicle to make a number of turns of the knob while the vehicle is in motion.

According to one aspect of the present invention, a control device comprises an angularly-movable, manually operable control element, and at least one mechanical-tohydraulic transducer having a mechanical input element which is connected to the control element by a transmission arrangement arranged to convert rotation of the control element reversibly into movement of the input element of the transducer or transducers, and the control device also including means arranged to prevent rotation of the control element in response to reaction forces exerted thereon by the mechanical-to-hydraulic transducer or tranducers.

Preferably, the transmission arrangement comprises a screw device, the lead of the screw being of the same order as the diameter of the screw. This provides a velocity ratio such that it is not necessary for the control element to be turned through a large number of turns to move the headlamps over their full range of movement. Preferably, the velocity ratio of the transmission arrangement is such that the input element of the mechanical-to-hydraulic transducer or transducers can be moved through its full travel by a rotation of the control element through less than 360".

The control knob may be attached to a spindle which is supported in a bore in a body part of the control device, the means for preventing rotation of the knob in response to the reaction forces comprising cooperating projections and recesses formed on the cooperating surfaces of the spindle and the bore. The spindle may be axially movable in the bore to disengage the cooperating projections and recesses. the spindle being connected to the transmission arrangement by a connection which can transmit rotation of the spindle but will not transmit the axial movement thereof. The control device may also include a spring acting between the spindle and the part of the transmission arrangement to which the spindle is connected, to bias the cooperating projections and recesses into engagement.

This spring may also provide resilient biasing of the input elements of the transducers, to oppose resilient biasing at the remote end of the hydraulic transmission; this feature forms the subject of our co-pending application No. 19104/77 (Serial No. 1576863).

In an alternative embodiment, the knob is attached to a spindle which has a threaded portion supported in a threaded bore in a body part of the control device, the lead of the threaded portion and bore being small in comparison with their diameter, to provide an irreversible connection which constitutes the means for preventing rotation of the control knob in response to the reaction forces.

In a third embodiment, the means arranged to prevent rotation of the knob in response to the reaction forces comprise a toothed wheel and a resilient detent, which rotate relative to one another when the knob is rotated, with the detent being biased into engagement with the teeth of the wheel. In this embodiment, as with the others, the input elements of the transducers may be resiliently biased; in one arrangement, the input element of the or each mechanical-to-hydraulic transducer comprises a hollow piston, which houses a helical compression spring which acts to bias the piston in the liquid-displacing direction.

The invention also provides, according to a second aspect, a headlamp system including a control device according to the first aspect, the or each hydraulic output from the control device being connected to a hydraulic-to-mechanical transducer which is arranged to vary the attitude of one of the headlamps of the system.

The invention may be carried into practice in various ways, but three specific headlamp control devices embodying the invention will now be described by way of example, with reference to the accompanying drawings, of which: Figure 1 is a half-section in side elevation through the first headlamp control device; Figure 2 is a cross-section of part of the device of Figure 1; Figure 3 is a longitudinal section of the second headlamp control device; Figure 4 is a side view in partial section of the third headlamp control device; Figure 5 is a view in section along line V-V in Figure 4, and Figure 6 is a plan view of the device of Figure 4.

The illustrated devices are all intended to be used in headlamp system such as that shown in Figure 1 of our patent specification No. 1, 469, 421. Thus, each headlamp control device has a manual adjusting knob, and a pair of mechanical-to-hydraulic transducers which are controlled by the adjusting knob. When the control device is installed in the complete headlamp control system, the outputs of these transducers are connected by respective conduits to hydraulic-to-mechanical transducers which are fitted to the headlamps whose position is to be adjusted.

Referring now to Figures 1 and 2 of the drawings, the first headlamp control device is shown at 8, and comprises a body 10, a control knob 12, and two pistons 18 which can be shifted axially by rotation of the control knob 12. The pistons 18 are sealed by rolling diaphragms 20, and constitute the mechanical-to-hydraulic transducers of the device.

Rotational movements of the knob 12 are converted into axial movements of the pistons 18 by a screw device which is generally indicated at 14. This screw device comprises a male threaded member 22, cooperating with a nut 24 which is formed integrally with the two pistons 18. The threaded member 22 is trapped between two parts of the body 10, so that it cannot move axially. In order that the member 22 can be rotated by rotation of the knob 12, a hexagonal bore 26 is provided in the member 22, and receives a corresponding hexagonal portion 32 of a spindle 28 which carries the knob 12.

The headlamp control device 8 also includes means, indicated generally at 16, for preventing unintentional rotation of the knob 12. Thus, the bore (indicated at 30) through which the spindle 28 emerges from the housing is provided with a number of keyways 36, shown best in Figure 2, while the spindle 28 is provided with a key 38. In the position illustrated in Figure 1, the key 38 is engaged with one of the keyways 36, preventing rotation of the knob 12 and the threaded member 22, but the knob 12 and the spindle 28 may be pushed manually to the left (as seen in Figure 1), so that the key 38 is disengaged from the keyway 36, allowing the knob 12 to be rotated, shifting the pistons 18 axially.The bore 26 contains a helical compression spring 40 which opposes this pressing-in of the knob 12; however, this spring cannot move the knob to the right from the position shown in Figure 1, because the hexagonal portion 32 is too large to pass through the bore 30.

The screw device 14 has a lead which is of the same order as the mean diameter of the screw, or even more. This can be expected to result in the screw device being reversible (i.e.

capable of converting axial movements to rotary movements), but the means 16 effectively prevent this from occurring except when adjustment is required. In contrast, it would probably be necessary to make the mean diameter at least 4 times the lead if no rotation-preventing means were used; this would avoid reversibility of the screw device. but would at the same time involve a reduced mechanical efficiency.

Whether the screw device 14 is reversible depends on the efficiency of the device, which depends in turn on the helix angle a, and the coefficient of friction K between the threads; in general, it is possible to neglect other sources of friction. if K = tan , it can be shown that the efficiency of the device 14 is given by tan a tan(a + ) With the materials normally used in constructing these devices, K will not be greater than 0.2; if the lead of the screw is equal to its mean diameter, giving a value for tan a of 0.318, the efficiency is above 50%. It may even be possible for the efficiency to exceed 65%.

The condition for reversibility can be approximately expressed as a > and it is possible for this condition to be satisfied even with values of lead which are not equal to the mean thread diameter.

When adjusting the height of the headlamps, the entire travel of the pistons 18 can be produced, in the example of Figure 1, by rotating the control knob 12 through an angle of about 200 . The force required for operation is not much greater than in a control element comprising a standard screw and nut system, since the efficiency of the device 14 is higher than that of a standard screw. It is thus possible, without reducing the accuracy of adjustment, to limit the motion required by the driver, whose attention may be fully occupied with driving.

The device shown in Figure 3 comprises a body 10, a knob 12, a nut 24, pistons 18 and diaphragms 20 which are all very similar to the corresponding parts in Figure 1. However, in this device, the nut 24 cooperates with a male thread 22' which is formed on the end of a spindle 28' which carries the knob 12. The spindle 28' is also formed with a male thread 42 which is threaded into a tapped bore 30' in the body 10; the lead of the thread 42 is small compared with its diameter, so that this threaded connection is irreversible, and thereforeprevents axial forces on the pistons 18 from resulting in rotation of the knob 12. The axial movement of the spindle 28' which occurs when the knob 12 is rotated is only small, and does not change the operation of the device much from that of Figure 1.

The headlamp control device 108 shown in Figures 4, 5 and 6 is generally similar to the devices of Figures 1, 2 and 3, having a body 110, a control knob 112, a screw device 114 for converting rotation of the knob 112 into linear movements, a pair of pistons 118 which form the moving elements of two mechanical-to-hydraulic transducers 105 and 106 and a device 116 for preventing rotation of the knob 112 under the effect of the reaction forces exerted by the transducers 105 and 106. The screw device 114 includes a male threaded member 122 and a nut 124, which is formed integrally with the pistons 118. The threaded member 122 is integral with a spindle 128 which is rotatably borne in the body 110 by two bearings 127 and 129, and which carries the knob 112. The spindle 128 also carries a toothed wheel 152 which forms part of the device 116 for preventing rotation of the knob 112.This device also includes a detent 150 which is secured to the body 110 by a screw 151, and has two arms which engage the toothed wheel 152 to hold the wheel against rotation. The detent is made of material which has sufficient resilience to allow the arms to be spread apart to allow rotation of the wheel 152 when a sufficient torque is applied to the knob 112; at other times, the arms are pressed resiliently into the position shown in Figure 5.

As well as the pistons 118, a sleeve 125 is also formed integrally with the nut 124, and is guided by a rod 123 which is fixed in openings 155 in the body 110. As an alternative, the rod 123 could move with the nut 124, sliding through the openings 155.

The pistons 118 are hollow, and are biased to the left (as seen in Figures 4 and 6) by two compression springs 140, which are partly housed inside the pistons 118. The springs 140 encircle two guide rods 154, which are fixed to the body 110 and prevent the springs from buckling. The purpose of the springs 140 is to oppose the tendency of the pistons 118 to move to the right, which is due to the biasing means which are normally associated with each of the headlamps controlled by the device, these biasing means are necessary because the hydraulic-to-mechanical transducers associated with the headlamps are single-acting.

In operation, the various forces acting on the pistons 118 will result in only a small torque on the spindle 128, and the detent 150 is easily able to hold the wheel 152 against rotation, while it is nonetheless easy for the driver of the vehicle to overcome the detent 150 and turn the knob 112 to adjust the headlamps.

WHAT WE CLAIM IS: 1. A control device comprising an angularly movable, manually operable control

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. in general, it is possible to neglect other sources of friction. if K = tan , it can be shown that the efficiency of the device 14 is given by tan a tan(a + ) With the materials normally used in constructing these devices, K will not be greater than 0.2; if the lead of the screw is equal to its mean diameter, giving a value for tan a of 0.318, the efficiency is above 50%. It may even be possible for the efficiency to exceed 65%. The condition for reversibility can be approximately expressed as a > and it is possible for this condition to be satisfied even with values of lead which are not equal to the mean thread diameter. When adjusting the height of the headlamps, the entire travel of the pistons 18 can be produced, in the example of Figure 1, by rotating the control knob 12 through an angle of about 200 . The force required for operation is not much greater than in a control element comprising a standard screw and nut system, since the efficiency of the device 14 is higher than that of a standard screw. It is thus possible, without reducing the accuracy of adjustment, to limit the motion required by the driver, whose attention may be fully occupied with driving. The device shown in Figure 3 comprises a body 10, a knob 12, a nut 24, pistons 18 and diaphragms 20 which are all very similar to the corresponding parts in Figure 1. However, in this device, the nut 24 cooperates with a male thread 22' which is formed on the end of a spindle 28' which carries the knob 12. The spindle 28' is also formed with a male thread 42 which is threaded into a tapped bore 30' in the body 10; the lead of the thread 42 is small compared with its diameter, so that this threaded connection is irreversible, and thereforeprevents axial forces on the pistons 18 from resulting in rotation of the knob 12. The axial movement of the spindle 28' which occurs when the knob 12 is rotated is only small, and does not change the operation of the device much from that of Figure 1. The headlamp control device 108 shown in Figures 4, 5 and 6 is generally similar to the devices of Figures 1, 2 and 3, having a body 110, a control knob 112, a screw device 114 for converting rotation of the knob 112 into linear movements, a pair of pistons 118 which form the moving elements of two mechanical-to-hydraulic transducers 105 and 106 and a device 116 for preventing rotation of the knob 112 under the effect of the reaction forces exerted by the transducers 105 and 106. The screw device 114 includes a male threaded member 122 and a nut 124, which is formed integrally with the pistons 118. The threaded member 122 is integral with a spindle 128 which is rotatably borne in the body 110 by two bearings 127 and 129, and which carries the knob 112. The spindle 128 also carries a toothed wheel 152 which forms part of the device 116 for preventing rotation of the knob 112.This device also includes a detent 150 which is secured to the body 110 by a screw 151, and has two arms which engage the toothed wheel 152 to hold the wheel against rotation. The detent is made of material which has sufficient resilience to allow the arms to be spread apart to allow rotation of the wheel 152 when a sufficient torque is applied to the knob 112; at other times, the arms are pressed resiliently into the position shown in Figure 5. As well as the pistons 118, a sleeve 125 is also formed integrally with the nut 124, and is guided by a rod 123 which is fixed in openings 155 in the body 110. As an alternative, the rod 123 could move with the nut 124, sliding through the openings 155. The pistons 118 are hollow, and are biased to the left (as seen in Figures 4 and 6) by two compression springs 140, which are partly housed inside the pistons 118. The springs 140 encircle two guide rods 154, which are fixed to the body 110 and prevent the springs from buckling. The purpose of the springs 140 is to oppose the tendency of the pistons 118 to move to the right, which is due to the biasing means which are normally associated with each of the headlamps controlled by the device, these biasing means are necessary because the hydraulic-to-mechanical transducers associated with the headlamps are single-acting. In operation, the various forces acting on the pistons 118 will result in only a small torque on the spindle 128, and the detent 150 is easily able to hold the wheel 152 against rotation, while it is nonetheless easy for the driver of the vehicle to overcome the detent 150 and turn the knob 112 to adjust the headlamps. WHAT WE CLAIM IS:

1. A control device comprising an angularly movable, manually operable control

element, and at least one mechanical-to-hydraulic transducer having a mechanical input element which is connected to the control elernent by a transmission arrangement arranged to convert rotation of the control element reversibly into movement of the input element of the transducer or transducers, and the control device also including means arranged to prevent rotation of the control element in response to reaction forces exerted thereon by the mechanical-to-hydraulic transducer or transducers.

2. A control device as claimed in Claim tin which the velocity ratio of the transmission arrangement is such that the input element of the mechanical-to-hydraulic transducer or transducers can be moved through its full travel by a rotation of the control element through less than 3600.

3. A control device as claimed in Claim 1 or Claim 2, in which the transmission arrangement has an efficiency of more than 50%.

4. A control device as claimed in Claim 1 or Claim 2 or Claim 3 which includes two mechanical-to-hydraulic transducers whose input elements are arranged to be moved in the same sense as one another by movements of the control element.

5. A control device as claimed in any of the preceding claims in which the transmission arrangement comprises a screw device, the lead of the screw being of the same order as the diameter of the screw.

6. A control device as claimed in any of the preceding claims, in which the control element is a rotatable knob.

7. A control device as claimed in Claim 6 in which the knob is attached to a spindle which is supported in a bore in a body part of the control device, the means for preventing rotation of the knob in response to the reaction forces comprising cooperating projections and recesses formed on the cooperating surfaces of the spindle and the bore.

8. A control device as claimed in Claim 7 in which the spindle is axially movable in the bore to disengage the cooperating projections and recesses, the spindle being connected to the transmission arrangement by a connection which can transmit rotation of the spindle but will not transmit the axial movement thereof.

9. A control device as claimed in Claim 8 which includes a spring acting between the spindle and the part of the transmission arrangement to which the spindle is connected, to bias the cooperating projections and recesses into engagement.

10. A control device as claimed in Claim 6 in which the knob is attached to a spindle which has a threaded portion supported in a threaded bore in a body part of the control device, the lead of the threaded portion and bore being small in comparison with their diameter, to provide an irreversible connection which constitutes the means for preventing rotation of the control knob in response to the reaction forces.

11. A control device as claimed in Claim 6 in which the means arranged to prevent rotation of the knob in response to the reaction forces comprise a toothed wheel and a resilient detent, which rotate relative to one another when the knob is rotated, with the detent being biased into engagement with the teeth of the wheel.

12. A control device as claimed in Claim 11 in which the toothed wheel is arranged to rotate with the knob, and the detent is fixed to a body part of the control device.

13. A control device as claimed in Claim 11 or Claim 12 in which the detent is double-armed, with both arms being in engagement with the wheel.

14. A control device as claimed in claim 5, or any of Claims 6 to 13 when appendant to Claim 5, the screw-threaded element of the transmission arrangement which is connected to the mechanical-to-hydraulic transducer or transducers being guided for linear movement by a guide rod which is housed at its ends in openings formed in a body part of the control device.

15. A control device as claimed in Claim 14 in which the guide rod is slidable in a guide sleeve which is integral with the guide screw-threaded element.

16. A control device as claimed in Claim 14 in which the guide rod is slidable in the openings in the body part, and is fixed to the guide screw-threaded element.

17. A control device as claimed in any of the preceding claims in which the input element of the or each mechanical-to-hydraulic transducer comprises a hollow piston, which houses a helical compression spring which acts to bias the piston in the liquid-displacing direction.

18. A control device as claimed in Claim 17 in which the or each spring is guided along a fixed guide rod.

19. A control device substantially as herein described, with reference to Figures 1 and 2, or Figure 3, or Figures 4, 5 and 6 of the accompanying drawings.

20. A headlamp system including a control device as claimed in any of the preceding claims, the or each hydraulic output from the control device being connected to a hydraulic-to-mechanical transducer which is arranged to vary the attitude of one of the headlamps of the system.

21. A system as claimed in Claim 20 in which the hydraulic-to-mechanical transducers are arranged to vary the angle of the headlamp axis to the horizontal.

22. A system as claimed in either of Claims 20 and 21 and as claimed in Claim 1 of Patent No. 1,469,421.