GB2568048A

GB2568048A - Dual arm variable tensioner

Info

Publication number: GB2568048A
Application number: GB1718083.7A
Authority: GB
Inventors: Duncombe Andrew
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2017-11-01
Filing date: 2017-11-01
Publication date: 2019-05-08
Also published as: GB201718083D0

Abstract

Apparatus 101 for variably tensioning a belt 102 on a pulley 103P of an internal combustion engine accessory 103 comprises first and second pulley supports 106, 107 configured to pivot in a common pivot plane about a common pivot axis (e.g. 103). First pulley 109 is mounted to the first pulley support at a location distal to the common pivot axis and a second pulley 113 is mounted to the second pulley support at a location distal to the common pivot axis. Biasing means 115 is configured to provide a torque about the common pivot axis to resiliently bias pivoting of the first and second pulley supports relative to each other about the common pivot axis. Varying means 116-120 is also provided for varying the torque provided by the biasing means wherein the biasing means comprises a first spring member. The apparatus may further comprise a second spring member 122 and may control the varying means according to a parameter that measures the torque applied between the first and second pulley supports.

Description

104P

DUAL ARM VARIABLE TENSIONER

TECHNICAL FIELD

The present disclosure relates to a dual arm variable tensioner. In particular, but not exclusively, it relates to a dual arm variable tensioner for a belt on a pulley of an internal combustion engine accessory.

Aspects of the invention relate to an apparatus for a dual arm variable tensioner, a controller for that apparatus, a drive system and vehicle including the apparatus or a controller for that apparatus.

BACKGROUND

Vehicles are known which include an internal combustion engine having a crankshaft and one or more engine accessories each of which comprises a pulley. The accessories are driven by or drive the crankshaft of the internal combustion engine via one or more belts which apply torque to or draw power from the pulleys. Such engine accessories may be an alternator, a belt integrated starter generator or an air conditioning compressor. Such belts are generally endless belts of known design.

It is known that to prevent the belt from slipping on or from the pulleys it is necessary that the belt is under sufficient tension to prevent that slippage. It is known to maintain or cause tension in the belt by the use of devices known as tensioners.

It is also known that the minimum amount of tension that the belt needs to be under to prevent slippage is related to the amount of torque being delivered to or drawn from the belt. The greater the amount of torque, the greater the minimum tension required to prevent slippage. It is also known that the greater the amount of tension a belt is under the greater the energy or work required to keep the belt turning around the pulleys. The greater the work required to cause the belt to pass around the pulleys the greater the fuel consumption by the internal combustion engine.

Existing tensioners are configured to put the belt under sufficient tension that the belt is prevented from slipping on or from the pulleys when the accessories or the crankshaft are drawing or delivering torque from or to the belt at their maximum capacity.

Dual arm tension tensioners are known and are located proximal to a pulley of an engine accessory. When in use such tensioners comprise tensioning rollers either side of the pulley. Such an arrangement is disclosed in DE10212209028 - Schaeffler Technologies AG. The dual arm tensioner of that disclosure is suitable for mounting around a pulley of an engine accessory that can either draw torque or deliver torque into the belt. The two tensioning rollers of the tensioner of DE102012209028 apply a pre-stressing force to the belt in front of and behind the pulley with which the tensioner is associated. In this context in front and behind are to be understood to relate to the direction of movement of the belt.

It is also known to provide a tensioner which may be adjusted by a controller to apply variable tension to a belt passing around the pulleys associated with one or more engine accessories and the crankshaft of an internal combustion engine. Such tensioners are provided in a fixed location relative to the pulleys of the engine accessories and the crankshaft and mounted so that operation of the tensioner causes a pulley to be moved into the belt, which increases its tension, or away from the belt, which decreases its tension.

It is an aim of the present invention to address disadvantages of the known tensioners.

SUMMARY OF THE INVENTION

Aspects of the embodiments of the invention provide an apparatus for a dual arm etensioner, a controller for that apparatus, a drive system and vehicle including the apparatus or a controller for the apparatus as claimed in the appended claims.

According to an aspect of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory, the apparatus comprising: first and second pulley supports configured to pivot in a common pivot plane about a common pivot axis; a first pulley rotatably mounted to the first pulley support at a location distal to the common pivot axis; a second pulley rotatably mounted to the second pulley support at a location distal to the common pivot axis; biasing means configured to provide a torque about the common pivot axis to resiliently bias pivoting of the first and second pulley supports relative to each other about the common pivot axis; and varying means for varying the torque provided by the biasing means; wherein the biasing means comprises a first spring member.

This provides the advantage that when the apparatus is mounted so that the first and second pulleys are either side of an engine accessory that may either draw power from or deliver torque to the belt, so ensuring optimal tensioning of the belt irrespective of whether the engine accessory is drawing power from the belt or delivering torque to the belt. Further, this arrangement allows the tension in the belt to be adjusted during the operation of the engine accessory if the tension in the belt is not at the value required. This is because the variation of the torque about the common pivot axis to resiliently bias pivoting of the first and second pulley supports relative to each other about the common pivot axis causes a variation in the tension in the belt. The advantage gained by being able to vary the tension in the belt is that when it is not required that the belt is under high tension so as to prevent slippage on the crank shaft pulley and or engine accessory pulleys, the tension can be decreased. This will result in less energy being needed to keep the belt passing around the pulleys. The decrease in the amount of energy required means the internal combustion engine needs to produce less energy and as such there is a reduction in the amount of fuel used by the internal combustion engine.

According to an embodiment the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the torque provided by the biasing means is varied during actuation of the varying means.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the first spring member provides torque in the common pivot plane about the common pivot access to bias the first and second pulley supports toward each other. This provides the advantage that the first and second pulleys continuously cause tension in the belt.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the biasing means further comprises a second spring member. This provides the advantage that the first and second spring members can work together to affect the amount of tension applied to the belt by the apparatus of the invention. The use of first and second spring members also has the advantage that springs are suitable for situations where there can be very rapid shock loads to a mechanical system because the springs can absorb such shock loads and then return to the desired configuration of the apparatus. Such shock loads are, for example experienced when a belt integrated starter generator is used to start rotation of the crankshaft of an internal combustion engine when that engine is started.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the second spring member has first and second ends, and the varying means comprises an element which is connected to and extends between one of the first and second pulley supports and one of the ends of the second spring member, and the other end of the second spring member is connected to the other of the first and second pulley supports.

This provides the advantage that the torque provided by the first and second spring members about the common pivot access to resiliently bias pivoting of the first and second pulleys support relative to each other about the common pivot axis can be altered by operation of the varying means because operation of the varying means alters the torque applied between the first and second pulley supports by the second spring member.

According to an embodiment of the invention there is provided apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the varying means comprises a varying arm rotatably connected via a pivot to the pulley support to which the varying means is connected, and a means for causing rotation of the varying arm about the pivot; and the second spring member is connected to the pulley support to which the varying means is connected via the varying arm and pivot. This provides the advantage that the amount of torque applied by the second spring member between the first and second pulley supports can be adjusted by rotation of the varying arm about the pivot by which it is connected to the pulley support. The range of values of torque applied between the first and second pulley supports by the second spring member caused by rotation of the pivot arm is a factor of the distance between the pivot about which the varying arm pivots and the position that the end of the second spring is connected to the varying arm. The greater the distance between the pivot and the end of the spring the greater the range of the torque applied by the second spring member.

According to an embodiment of the invention there is provided apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the means for causing rotation of the varying arm about the pivot comprises a pinion gear, and a number of teeth in a fixed spatial relationship with the varying arm, the teeth are suitable for meshing with the pinion gear, the pinion gear and the teeth are meshed, and rotation of the pinion gear causes rotation of the varying arm about the pivot.

This provides the advantage that rotation of the varying arm about the pivot may be accurately controlled by rotation of the pinion gear. The rotation of the pinion gear may be in either direction so allowing the torque applied between the first and second pulley supports by the biasing means to be increased or decreased.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the varying means comprises an electric motor. This provides the advantage that the varying means can be actuated and controlled by electronic means and without active intervention from a user or operator of the internal combustion engine. Further, the varying means can be actuated whilst the internal combustion engine is running without endangering the user or operator of the internal combustion engine.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein one or both of the first and second pulley supports comprises a lock means for reversibly locking the first and second pulley supports in a fixed position relative to each other. This has the advantage that the position of the first and second arms can, reversibly, be fixed relative to each other if that is required. This may be required when the apparatus of the invention is to be installed, serviced, or in the period between manufacture of the apparatus and its installation.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory which comprises a controller adapted to receive a signal and to operate the varying means in dependence on that signal. This provides the advantage that the apparatus of the invention can be caused to be responsive to one or more parameters associated with the internal combustion engine, an engine accessory, tension in the belt, torque applied between the first second and second pulley supports or any other parameter directly or indirectly derived from one of the aforesaid sources.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the apparatus comprises a means for measuring a parameter resultant from the torque applied between the first and second pulley supports and a means to generate a signal in dependence on that parameter.

This provides the advantage that the signal generated can be used in connection with the actuation of the varying means of the apparatus of the invention. This way, the varying means can be actuated when the tension in the belt, and as a result the torque applied between the first and second pulley supports changes and not in dependence on one or more operational parameters of the internal combustion engine or an engine accessory.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the means for measuring the parameter and generating the signal comprises one or more of a potentiometer, torque sensor, or a transducer.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the parameter is the degree of rotation between the first and second pulley supports about the common pivot axis. This provides the advantage that the parameter measured is directly dependent on any change in torque applied between the first and second pulley supports.

According to an embodiment of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the varying means comprises a linear actuator; a motor, a lead screw, and a nut; a motor, a ball screw, and a nut; a motor, a rack, and a pinion; a motor, a curved rack, and a pinion; a motor, a pinion, and a gear; or a motor and a linkage mechanism. This provides the advantage that operation of the varying means may directly or indirectly change the torque applied between the first and second pulley supports. The change may be to increase or decrease that torque.

According to a further aspect of the present invention there is provided a drive system for a vehicle comprising an internal combustion engine, an internal combustion engine accessory, a belt configured to transmit torque between the internal combustion engine and the accessory, and an apparatus as herein before described wherein the apparatus is arranged to provide variable tension in the belt.

According to a further aspect of the present invention there is provided a vehicle comprising an internal combustion engine, an internal combustion engine accessory, a belt configured to transmit torque between the internal combustion engine and the accessory, and an apparatus as herein before described wherein the apparatus is arranged to provide variable tension in the belt.

According to a further aspect of the present invention there is provided a controller for controlling the varying means of the apparatus wherein the controller comprises: means for receiving one or more signals each indicative of a parameter resultant from the torque applied between the first and second pulley supports comprising an electronic processor having an electrical input for receiving one or more signals each indicative of a parameter resultant from the torque applied between the first and second pulley supports; an electronic memory device electrically coupled to the electronic processor and having instructions stored therein; and the electronic processor being configured to access the memory device and execute the instructions stored therein based on the values of the parameter resultant from the torque applied between the first and second pulley supports (106, 107); and means to actuate the varying means.

This provides the advantage that the apparatus of the invention can vary the torque applied between the first and second pulley supports and hence the tension in the belt according to a predetermined set of instructions stored in the controller.

According to a further aspect of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory, the apparatus comprising: first and second pulley supports configured to pivot in a common pivot plane about a common pivot axis; a first pulley rotatably mounted to the first pulley support at a location distal to the common pivot axis; a second pulley rotatably mounted to the second pulley support at a location distal to the common pivot axis; a support structure comprising a pivot about which the first and second pulley supports may pivot and in which the support structure is adapted to be mounted adjacent to an engine accessory; a biasing means configured to provide a torque about the common pivot axis to resiliently bias pivoting of the first and second pulley supports relative to each other about the common pivot axis; and varying means for varying the torque provided by the biasing means; wherein the biasing means comprises a first spring member.

According to a further aspect of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory, the apparatus comprising: first and second pulley supports configured to pivot in a common pivot plane about a common pivot axis; a first pulley rotatably mounted to the first pulley support at a location distal to the common pivot axis; a second pulley rotatably mounted to the second pulley support at a location distal to the common pivot axis; a support structure comprising a pivot about which the first and second pulley supports may pivot and in which the support structure is adapted to be mounted adjacent to an engine accessory; a biasing means configured to provide a torque about the common pivot axis to resiliently bias pivoting of the first and second pulley supports relative to each other about the common pivot axis; and varying means for varying the spring constant of the biasing means; wherein the biasing means comprises a first spring member.

According to a further aspect of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the first spring member provides a rotational force in the common pivot plane about the common pivot axis to bias the first and second pulley supports toward a predetermined position relative to each other.

According to a further aspect of the invention there is provided an apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory wherein the first spring member provides a rotational force in the common pivot plane about the common pivot axis to bias the first and second pulley supports away from each other.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a front view of an embodiment of the invention having example apparatus 101 for tensioning a belt 102 which is mounted on an engine accessory pulley 103 when the belt 102 is in a first tension configuration;

Figure 2 shows a front view of the example apparatus 101 when the belt 102 is in a second tension configuration;

Figure 3 shows a front view of the example apparatus 101 when the belt 102 is in a third tension configuration;

Figure 4 shows a front view of the example apparatus 101 when the belt 102 is in a fourth tension configuration;

Figure 5 shows schematically the example apparatus 101 adjacent an engine accessory 103 located within a vehicle 201;

Figure 6 shows a front view of an embodiment of the invention having an example apparatus 301 for tensioning a belt 102 which is mounted on an engine accessory pulley 103;

Figure 7 shows a front view of an embodiment of the invention having an example apparatus 401 for tensioning a belt 102 which is mounted on an engine accessory pulley 103;

Figure 8 shows a front view of an embodiment of the invention having an example apparatus 501 for tensioning a belt 102 which is mounted on an engine accessory pulley 103;

Figure 9 shows a front view of an embodiment of the invention having an example apparatus 601 for tensioning a belt 102 which is mounted on an engine accessory pulley 103;

Figure 10 shows a front view of an embodiment of the invention having an example apparatus 701 for tensioning a belt 102 which is mounted on an engine accessory pulley 103;and

Figure 11 shows a front view of an embodiment of the invention having an example apparatus 801 for tensioning a belt 102 which is mounted on an engine accessory pulley 103;

DETAILED DESCRIPTION

With reference to Figures 1, 2, 3, 4, and 5, a vehicle 201 comprises an internal combustion engine 202, a crankshaft 104, an engine accessory 103, and a second engine accessory

105. Each of the engine accessory 103, crankshaft 104, and second engine accessory 105 comprise a pulley 103P, 104P and 105P respectively. Passing around pulleys 103P, 104P and 105P is an endless belt 102. The endless belt 102 may be a V belt, V-ribbed belt, or other belt appropriate for use in association with torque transfer between an internal combustion engine crankshaft and one or more engine accessories.

To introduce tension into the belt 102 so as to prevent the belt 102 from coming off pulleys 103P, 104P and 105P or slipping on those pulleys there is provided a belt tensioner in the form of the example apparatus 101.

The example apparatus 101 comprises a first pulley support 106 and a second pulley support 107. Both of the first pulley support 106 and second pulley support 107 are configured to pivot in a common pivot plane about a common pivot axis which is substantially coincident with the axis about which pulley 103P may rotate.

The first pulley support 106 is comprised of a first pivot arm 108 which extends away from the common pivot axis and to which a first pulley 109 is rotatably mounted via a pivot 110. The first pulley support 106 is also comprised of a first support arm 111. The second pulley support 107 is comprised of a second pivot arm 112 which extends away from the common pivot axis and to which a second pulley 113 is rotatably mounted via a pivot 114.

Attached to the ends of the first and second pivot arms 108, 112 are the ends of a biasing means in the form of a spring member 115. Spring member 115 is a horseshoe spring or a yoke spring. When no other forces are acting on the first and second pulley supports 106, 107 the spring member 115 biases the first and second pivot arms 108, 112 and hence first and second pulleys 109, 113 towards each other by applying a torque about the common pivot axis.

The example apparatus 101 further comprises a varying means for varying the torque applied about the common pivot axis by the spring member 115. That varying means comprises a pinion 116 attached to the drive shaft 117 of an electric motor 118. The electric motor 118 is fixed to the first support arm 111 of the first pulley support 106.

The varying means further comprises gear wheel 119 to which is rigidly fixed a varying arm 120. The gear wheel 119 has teeth 121 around at least a portion of its circumference, those teeth being suitably dimensioned to mesh with the teeth of the pinion 116. The gear wheel 119 is pivotally mounted on the pivot 110. The end 123 of the varying arm 120 distal from the pivot 110 is provided with a means for attachment of a first end of a second spring member 122. The second end of the second spring member 122 is attached to the second pivot arm 112 at a position proximal to the pivot 114. The second spring member 122 is a tension spring.

The second spring member 122 is in tension and that tension increases the torque applied about the common pivot axis between the first and second pulley supports 106, 107 by the spring member 115 to bias the first and second pulley supports 106, 107 towards each other. Actuation of the varying means, that is actuation of the electric motor 118 to rotate pinion 116, causes the gear wheel 119 to be rotated about pivot 110. Rotation of the gear wheel 119 about pivot 110 causes the varying arm 120 to pivot and the distance between the end 123 of the varying arm 120 and the pivot 114 and hence the tension in the second spring member 122 to be increased (if in Figure 1, 2, 3, or 4 the gear wheel 119 is rotated clockwise) or decreased (if in Figure 1, 2, 3, or 4 the gear wheel 119 is rotated anticlockwise).

The example apparatus 101 further comprises a support structure 124. The support structure 124 comprises a pivot, not shown, about which the first and second pulley supports

106, 107 may pivot. The support structure 124 is adapted to be mounted adjacent to an engine accessory 103 using bolts 125. Other suitable fixing means may be used.

The first and second pulleys 109, 113 are so located that when the support structure 124 is mounted adjacent to an engine accessory 103 the belt 102 passes between the pivots 110 and 114 and around the first and second pulleys 109, 113. Tension in the belt 102 causes the belt 102 to push the first and second pulleys 109, 113 away from each other. The biasing means, the spring member 115 and second spring member 122 in the example apparatus 101, is configured so that the torque applied about the common pivot axis between the first and second pulley supports 106, 107 by the spring member 115 and second spring member 122 is sufficient to cause the belt 102 to be under a predetermined amount of tension. Actuation of the varying means causing a change in the tension in the second spring member 122 results in a change in the tension in the belt 102. In a similar fashion, a change in the degree of tension in the belt 102 will result in extension or compression or deflection of the spring member 115 and second spring member 122 which in turn will result in a change in the torque applied about the common pivot axis between the first and second pulley supports 106, 107 by the spring member 115 and second spring member 122.

The example apparatus 101 thus has the advantage that the tension in the belt can be decreased for the tension required for maximum torque transmission when maximum torque transmission is not required. This leads to a saving in energy in turning the belt 102 around the pulleys 133P, 104P, 105P and hence to a reduction in the fuel used by the internal combustion engine.

The example apparatus 101 further comprises a means for determining the torque applied about the common pivot axis by the spring member 115 and second spring member 122 in the form of a torque sensor 126. That torque sensor 126 is adapted to produce a signal in dependence on the torque determined. That signal is transmitted by means, not shown, to a controller, not shown, which is adapted to receive that signal and operate the varying means in dependence on that signal.

The example apparatus 101 shown in Figure 1 is in the orientation adopted by the example apparatus 101 when the tension in in the portion 127 of the belt 102 between the pulley

104P and the first pulley 109 is substantially equal to the tension in the portion 128 of belt 102 between the second pulley 113 and the pulley 105P.

When, as shown in Figure 2, the tension in portion 127 of belt 102 is greater than the tension in portion 128 of belt 102 the belt will push the first pulley 109 away from the second pulley 113. The increase in the torque applied about the common pivot axis between the first and second pulley supports 106, 107 that the relative movement of the first pulley 109 will cause has been decreased in Figure 2 by rotation of the gear wheel 119 in an anti-clockwise direction to decrease the tension in the second spring member 122. If the tension in the belt as a whole needed to be increased, because, for example, the increase in the relative tension in portion 127 of belt 102 indicated that an increased amount of torque is being transmitted through the belt 102 and as such the risk of the belt 102 slipping on one or more of the pulleys 103P,104P or 105P is increased, then gear wheel 119 would be rotated clockwise to increase the tension in the second spring member and thus the torque applied about the common pivot axis between the first and second pulley supports 106, 107.

When, as shown in Figures 3 and 4, the tension in portion 128 of belt 102 is greater than the tension in portion 127 of belt 102 the belt will push the first pulley 113 away from the second pulley 109. In the same way as described in connection with Figure 2, the increase in the torque applied about the common pivot axis between the first and second pulley supports 106, 107 can be adjusted using the varying means.

The example apparatus 101 is shown schematically in Figure 5 adjacent to an engine accessory 103 located within a vehicle 201. In this embodiment the engine accessory is a belt integrated starter generator. The vehicle has a drive system 203 comprising an internal combustion engine 202, the starter generator 103, the belt 102, and the example apparatus 101 which is arranged to provide variable tension in the belt 102.

During operation of the vehicle the internal combustion engine 202 is used to provide torque required to power movement of the vehicle 201 but, as is known in hybrid vehicles, some of the power produced by the engine 202 may be used to provide power to the starter generator 103, which in its generation mode generates electricity. The generated electricity is stored within one or more batteries 204.

A portion of the power generated by the engine 202 may also be used to provide power to another engine accessory 105. Engine accessory 105 may be an air-conditioner compressor.

With reference to Figure 6, the elements of the embodiment shown in Figure 6 which are in common with Figures 1,2,3 and 4 have the same numbering and are as described with reference to Figures 1,2, 3 and 4.

In the example apparatus 301 the apparatus 301 is arranged as in the example apparatus 101 with the exception that the varying arm 320 is longer than the varying arm 120, and the second spring member 322 is longer than second spring member 122. The operation of the example apparatus 301 is as described with reference to the example apparatus 101. The increase in the length of the varying arm 320 increases the range of tensions that may be caused in the second spring member 322 relative to spring member 122 if the springs are manufactured from the same materials.

The example apparatus 301 can be incorporated into a vehicle 201 in the same fashion as the example apparatus 101 as described in connection with Figure 5.

With reference to Figure 7, the elements of the embodiment shown in Figure 7 which are in common with Figures 1,2,3 and 4 have the same numbering and are as described with reference to Figures 1,2, 3 and 4 unless otherwise described.

In the example apparatus 401 the varying means comprises a lead screw 402, an electric motor 403 for driving the lead screw 402, and a motor plate 404. The motor plate 404 is pivotally attached to pivot 114 on second pulley support 107. The electric motor 403 is rigidly connected to the motor plate 404, and actuation of the motor 403 causes rotation of the lead screw 402 about its longitudinal axis.

The varying means further comprises a pair of thread engaging means 405 attached to the first support arm 111 of the first pulley support 107. The thread engaging means 405 are attached to the first support arm 111 of the first pulley support 107 in such a fashion and in positions relative to each other such that the positions of pivots 110 and 114 can alter a little relative to each other in a direction not parallel with the longitudinal axis of the lead screw 402 without damage to the lead screw 402 or thread engaging means 405.

When the electric motor 403 is actuated the rotation of the lead screw 402 about its longitudinal axis will, depending upon the direction of rotation decrease the distance between pivot 114 and thread engaging means 405 and hence between first and second pulleys 109, 113, or increase the distance between pivot 114 and thread engaging means 405 and hence between first and second pulleys 109, 113. The tension in belt 102 caused by the example apparatus 401 is dependent on the distance between first and second pulleys 109, 113 and can thus be altered by actuation of the lead screw 402.

The example apparatus 401 can be incorporated into a vehicle 201 in the same fashion as the example apparatus 101 as described in connection with Figure 5.

With reference to Figure 8, the elements of the embodiment shown in Figure 8 which are in common with Figures 1,2,3 and 4 have the same numbering and are as described with reference to Figures 1,2, 3 and 4 unless otherwise described.

In the example apparatus 501 the varying means comprises a rack 502 which is provided with teeth 507 and which is pivotally attached to pivot 114. The varying means further comprises a pinion 503 attached to the drive shaft 504 of a motor 505, and a guide roller 506. The teeth of the pinion 503 and teeth 507 of the rack 502 are configured to mesh and the guide roller 506 is located so as to prevent the rack 502 moving away from the pinion 503 and the teeth of the pinion 503 and teeth 507 of the rack 502 disengaging from each other. The motor 505 is rigidly fixed to the first support arm 111 of the first pulley support 106.

The pinion 503 and guide roller 506 are attached to the first support arm 111 of the first pulley support 107 in such a fashion and in positions relative to each other such that the positions of pivots 110 and 114 can alter a little relative to each other in a direction not parallel with the longitudinal axis of the rack 502 without damage to the rack 502, motor 505, drive shaft 504, pinion 503, or guide roller 506.

When the electric motor 505 is actuated the rotation of the pinion 503 will, depending upon the direction of rotation, decrease the distance between pivot 114 and pinion 503 and hence between first and second pulleys 109, 113, or increase the distance between pivot 114 and pinion 503 and hence between first and second pulleys 109, 113. The tension in belt 102 caused by the example apparatus 501 is dependent on the distance between first and second pulleys 109, 113 and can thus be altered by actuation of the motor 505.

The example apparatus 501 can be incorporated into a vehicle 201 in the same fashion as the example apparatus 101 as described in connection with Figure 5.

With reference to Figure 9, the elements of the embodiment shown in Figure 9 which are in common with Figures 1,2,3 and 4 have the same numbering and are as described with reference to Figures 1,2, 3 and 4 unless otherwise described.

In the example apparatus 601 the varying means comprises a means for varying the torque applied about the common pivot axis by the spring member 115. That varying means comprises a pinion 602 attached to the drive shaft 603 of an electric motor 604. The electric motor 604 is fixed to the first support arm 111 of the first pulley support 106.

The varying means further comprises a gear wheel 606 to which is rigidly fixed a varying arm 605. The gear wheel 606 has teeth 607 around at least a portion of its circumference, those teeth being suitably dimensioned to mesh with the teeth of the pinion 602. The gear wheel 606 is pivotally mounted on the pivot 110. The end 608 of the varying arm 605 distal from the pivot 110 is provided with a pivot 609. The pivot 609 and the end 605 of spring member 115 not attached to the second pulley support 107 are adapted to allow the end 605 of spring member 115 to pivotally attach to the pivot 609.

When the electric motor 604 is actuated then the rotation of the pinion 602 will cause the gear wheel 606 to rotate and the varying arm 605 will rotate about pivot 110. The rotation of the varying arm 605 will cause the spring member 115 to be deflected and as a result change the torque applied about the common pivot axis between the first and second pulley supports 106, 107 by the spring member 115.

The example apparatus 601 can be incorporated into a vehicle 201 in the same fashion as the example apparatus 101 as described in connection with Figure 5.

With reference to Figure 10, the elements of the embodiment shown in Figure 10 which are in common with Figures 1, 2, 3 and 4 have the same numbering and are as described with reference to Figures 1,2, 3 and 4 unless otherwise described.

In the example apparatus 701 the varying means comprises a pinion 702 attached to the drive shaft 703 of an electric motor 704. The electric motor 704 is fixed to the first support arm 111 of the first pulley support 106.

The varying means further comprises a gear wheel 706 to which is rigidly fixed a first varying arm 705. The gear wheel 706 has teeth 707 around at least a portion of its circumference, those teeth being suitably dimensioned to mesh with the teeth of the pinion 702. The gear wheel 706 is pivotally mounted on the pivot 110. The end 708 of the first varying arm 705 distal from the pivot 110 is provided with a pivot 709. Pivotally attached to the pivot 709 is a first end of a second varying arm 710. The second end of the second varying arm 710 is pivotally attached to the pivot 114 attached to the second pulley support 107. Together the first and second varying arms 705, 710 form a linkage mechanism 711.

When the electric motor 704 is actuated then the rotation of the pinion 702 will cause the gear wheel 706 to rotate and the varying arm 705 will rotate about pivot 110. The rotation of the gear wheel 706 and the varying arm 705 in a clockwise direction, as shown in Figure 10, will cause the linkage mechanism 711 to pull the pivots 110 and 114 towards each other. Rotation of the gear wheel 706 and the varying arm 705 in an anti-clockwise direction, as shown in Figure 10, will cause the linkage mechanism 711 to push the pivots 110 and 114 away from each other. Change in the distance between the pivots 110 and 114 will result in a change in the tension in the belt 102.

The example apparatus 701 can be incorporated into a vehicle 201 in the same fashion as the example apparatus 101 as described in connection with Figure 5.

With reference to Figure 11, the elements of the embodiment shown in Figure 11 which are in common with Figures 1, 2, 3 and 4 have the same numbering and are as described with reference to Figures 1,2, 3 and 4 unless otherwise described.

In the example apparatus 801 the varying means comprises a pinion 802 attached to the drive shaft 803 of an electric motor 804. The electric motor 804 is fixed to the first support arm 111 of the first pulley support 106.

The varying means further comprises a gear plate 806 which is fixed to the second pulley support 107 via a number of fixings 809. The fixings 809 may be any appropriate type of fixing, a non-limiting example of such a fixing is a bolt. The gear plate 806 can be fixed directly to the second pulley support 107, not shown, or via spokes 810. Spokes 810 may be rigid or elastically deformable, for example a mono leaf spring.

The gear plate 806 has teeth 811 around at least a portion of its circumference, those teeth being suitably dimensioned to mesh with the teeth of the pinion 802.

When the electric motor 804 is actuated the rotation of the pinion 802 will, depending upon the direction of rotation, decrease the distance between pivots 110 and 114 and hence between first and second pulleys 109, 113, or increase the distance between pivots 110 and 114 and hence between first and second pulleys 109, 113. The tension in belt 102 caused by the example apparatus 801 is dependent on the distance between first and second pulleys 109, 113 and can thus be altered by actuation of the motor 804.

The example apparatus 801 can be incorporated into a vehicle 201 in the same fashion as the example apparatus 101 as described in connection with Figure 5.

For purposes of this disclosure, it is to be understood that the controller(s) described herein can each comprise a control unit or computational device having one or more electronic processors. A vehicle and/or a system thereof may comprise a single control unit or electronic controller or alternatively different functions of the controller(s) may be embodied in, or hosted in, different control units or controllers. A set of instructions could be provided which, when executed, cause said controller(s) or control unit(s) to implement the control techniques described herein (including the described method(s)). The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software to be executed by one or more electronic processor(s). For example, a first controller may be implemented in software run on one or more electronic processors, and one or more other controllers may also be implemented in software run on or more electronic processors, optionally the same one or more processors as the first controller. It will be appreciated, however, that other arrangements are also useful, and therefore, the present disclosure is not intended to be limited to any particular arrangement. In any event, the set of instructions described above may be embedded in a computerreadable storage medium (e.g., a non-transitory computer-readable storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational device, including, without limitation: a magnetic storage medium (e.g., floppy diskette); optical storage medium (e.g., CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM ad EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. Apparatus for variably tensioning a belt on a pulley of an internal combustion engine accessory, the apparatus comprising:

first and second pulley supports configured to pivot in a common pivot plane about a common pivot axis;

a first pulley rotatably mounted to the first pulley support at a location distal to the common pivot axis;

a second pulley rotatably mounted to the second pulley support at a location distal to the common pivot axis;

biasing means configured to provide a torque about the common pivot axis to resiliently bias pivoting of the first and second pulley supports relative to each other about the common pivot axis; and varying means for varying the torque provided by the biasing means; wherein the biasing means comprises a first spring member.

2. Apparatus according to claim 1 wherein the torque provided by the biasing means is varied during actuation of the varying means.

3. Apparatus according to claim 1 or 2 wherein the first spring member provides a torque in the common pivot plane about the common pivot axis to bias the first and second pulley supports towards each other.

4. Apparatus according to any of claims 1 to 3 wherein the biasing means further comprises a second spring member.

5. Apparatus according to claim 4 wherein the second spring member has first and second ends, and the varying means comprises an element which is connected to and extends between one of the first and second pulley supports and one of the ends of the second spring member, and the other end of the second spring member is connected to the other of the first and second pulley supports.

6. Apparatus according to claim 5 wherein the varying means comprises a varying arm rotatably connected via a pivot to the pulley support to which the varying means is connected, and a means for causing rotation of the varying arm about the pivot; and the second spring member is connected to the pulley support to which the varying means is connected via the varying arm and pivot.

7. Apparatus according to claim 5 or 6 wherein the means for causing rotation of the varying arm about the pivot comprises a pinion gear and a number of teeth in a fixed spatial relationship with the varying arm, the teeth are suitable for meshing with the pinion gear, the pinion gear and the teeth are meshed, and rotation of the pinion gear causes rotation of the varying arm about the pivot.

8. Apparatus according to any of claims 1 to 7 in which the varying means comprises an electric motor.

9. Apparatus according to any of claims 1 to 8 wherein one or both of the first and second pulley supports comprises a lock means for reversibly locking the first and second pulley supports in a fixed position relative to each other.

10. Apparatus according to any of claims 1 to 9 wherein the apparatus comprises a controller adapted to receive a signal and to operate the varying means in dependence on that signal.

11. Apparatus according to any of claims 1 to 10 wherein the apparatus comprises a means for measuring a parameter resultant from the torque applied between the first and second pulley supports and a means to generate a signal in dependence on that parameter.

12. Apparatus according to claim 11 wherein the means for measuring the parameter and generating the signal comprises one or more of a potentiometer, torque sensor, or a transducer.

13 Apparatus according to claim 11 or 12 wherein the parameter is the degree of rotation between the first and second pulley supports about the common pivot axis.

14. Apparatus according to any of claims 1 to 13 wherein the varying means comprises a linear actuator; a motor, a lead screw, and a nut or mechanical equivalent; a motor, a ball screw, and a nut; a motor, a rack, and a pinion; a motor, a curved rack, and a pinion; a motor, a pinion, and a gear; or a motor and linkage mechanism.

15. A drive system for a vehicle comprising an internal combustion engine, an internal combustion engine accessory, a belt configured to transmit torque between the internal combustion engine and the accessory, and an apparatus according to any of claims 1 to 14 wherein the apparatus is arranged to provide variable tension in the belt.

16. A vehicle comprising an internal combustion engine, an internal combustion engine accessory, a belt configured to transmit torque between the internal combustion engine and the accessory, and an apparatus according to any of claims 1 to 14 wherein the apparatus is arranged to provide variable tension in the belt.

17. A controller for controlling the varying means according to any of claims 1 to 14 wherein the controller comprises:

means for receiving one or more signals each indicative of a parameter resultant from the torque applied between the first and second pulley supports comprising an electronic processor having an electrical input for receiving one or more signals each indicative of a parameter resultant from the torque applied between the first and second pulley supports;

an electronic memory device electrically coupled to the electronic processor and having instructions stored therein; and the electronic processor being configured to access the memory device and execute the instructions stored therein based on the values of the parameter resultant from the torque applied between the first and second pulley supports; and means to actuate the varying means.

18. A control system for a vehicle configured to variably tension a belt on a pulley of an internal combustion engine accessory comprising a controller according to claim 17.

19. A vehicle comprising a control system according to claim 18.