BACKGROUND OF THE INVENTION

[0001] The invention relates to a method of driving a feed conveyor, the method comprising: driving a conveyor belt as an endless loop between a feed station and a discharge station of the feed conveyor, the upper belt section serving as a transport section; placing the feed conveyor in an inclined position for the duration of use in such a manner that the transport section has an inclination of ascent relative to the horizontal plane; feeding material to be conveyed onto an upper surface of the conveyor belt at the feed station, the material generating a material layer on the belt conveyed in the transport section; and controlling the thickness of the material layer in the transport section.

[0002] The invention further relates to a feed conveyor comprising: a conveyor belt, which is a piece in the form of a closed loop, which is arranged around at least two pulley drums, the upper section of which is a transport section and the lower section of which is a return section; at least one driving motor arranged to rotate at least one pulley drum around its longitudinal axis, the roll being arranged to transmit the movement to the conveyor belt and generate a rate of movement therefor; a feed station for feeding material to be conveyed to the transport section of the conveyor belt; a discharge station for discharging the materia! conveyed on the transport section; and at least one support member for supporting the feed conveyor to an inclined position for the duration of use, the transport section of the conveyor belt having an inclination of ascent relative to the horizontal level.

[0003] The invention still further relates to a crusher comprising: a movable carrier; a crusher unit comprising crusher members for reducing the particle size of material to be processed, a feed opening for feeding the material to be processed to the crusher members, and discharging means for discharging processed material; a feed conveyor for conveying material to be crushed to the crusher unit, the feed conveyor being arranged in an inclined position relative to the carrier and comprising a conveyor belt in the shape of a closed loop and arranged around at least two pulley drums, and arranged to be driven by means of a driving motor, and the feed conveyor comprising a feed station for feeding the material to be processed to a transport section of the conveyor belt, and the feed conveyor further comprising a discharge station wherein the material to be processed is discharged from the conveyor belt;

means for affecting the thickness of a materia! layer conveyed on the conveyor belt of the feed conveyor; and further a discharge conveyor for discharging the material processed from the crusher unit.

[0004] Known feed conveyors have a given angular position to which they are fixedly installed. The feed stations of feed conveyors are provided with limiting surfaces that 'cut' the thickness of the materia! layer transferred to the conveyor belt for conveying, when necessary, for avoiding excess capacity of the conveyor. At its simplest, the limiting surface is an opening or a transverse boom or a corresponding surface arranged above the conveyor belt, which, in a manner of speaking, 'cuts' off extra material. The material surface has to be 'cut' particularly when large batches of materia! are loaded to the feed station from the bucket of a wheel loader or the like, for example. The drawback in such an arrangement is that the limiting surface is subjected to large forces and wearing stresses, wherefore the durability of the limiting surface may present a problem. 'Cutting' a material layer into a suitable thickness by means of the limiting surface is subject to the feed conveyor having enough power. The driving motor, power transmission and conveyor belt of a feed conveyor are subjected to large stresses, which has to be taken into consideration in dimensioning said components. Furthermore, known feed conveyors consume a large amount of energy for limiting the thickness of a material layer to be conveyed, which naturally increases the operating costs of feed conveyors.

BRIEF DESCRIPTION OF THE INVENTION

[0005] The object of the present invention is to provide a new and improved method of driving a feed conveyor, a feed conveyor and a crusher.

[0006] The method of the invention is characterized by monitoring the thickness of the material layer; and adjusting the inclination of ascent of at least the feed conveyor for adjusting the thickness of the material layer.

[0007] The conveyor of the invention is characterized in that the feed conveyor is coupled to a carrier along the section at the end on the side of the feed station with at ieast one turning link; the support member comprises at least one lifting device for adjusting the inclination of ascent of the feed conveyor; and the thickness of the material layer in the transport section is arranged to be adjusted by adjusting at least the inclination of ascent.

[0008] The crusher of the invention is characterized in that the feed conveyor is coupled to the carrier at its end on the side of the feed station by

means of a turning link; the crusher comprises at least one lifting device for lifting and lowering the end of the feed conveyor on the side of the discharge station for adjusting the inclination of the feed conveyor to an inclination of ascent relative to the horizontal plane; the thickness of the material layer conveyed on the feed conveyor is adjustable by changing the inclination of ascent of the feed conveyor; and the crusher comprises at least one displacing device for displacing the feed conveyor in the longitudinal direction relative to the crusher unit, the position of the falling point of the material flow falling off the feed conveyor in the feed opening of the crusher unit being adjustable.

[0009] The second crusher of the invention is characterized in that the feed conveyor is coupled to the carrier at its end on the side of the feed station by means of a turning link; the crusher comprises at least one lifting device for lifting and lowering the end of the feed conveyor on the side of the discharge station for adjusting the inclination of the feed conveyor to an inclination of ascent relative to the horizontal plane; and the thickness of the material layer conveyed on the feed conveyor and the capacity of the conveyor are adjustable by changing the inclination of ascent of the feed conveyor.

[0010] An idea of the invention is that the thickness of the material layer conveyed with the feed conveyor is not limited by means of mechanical limiting surfaces, but by adjusting the control parameters of the conveyor. This being so, such a material layer is conveyed with the feed conveyor whose thickness is smaller than the shortest distance at the feed station from the moving upper surface of the conveyor belt to the nearest stationary structure above it. By adjusting the inclination of ascent of the feed conveyor, the thickness of the material layer batched onto the conveyor belt at the feed station can be influenced.

[0011] An advantage of the invention is that the adjustment of the thickness of the material layer does not subject the power transmission and conveyor belt of the feed conveyor to any extra stresses. In addition, no limiting surfaces are required for limiting the thickness of the material layer. Overall, thanks to the invention, fewer loads and less wearing stress are directed to the structure of the feed conveyor, wherefore the feed conveyor may be more durable than previously and its need for maintenance may be smaller. Furthermore, the energy consumption in the feed conveyor according to the invention may be distinctly lower than in solutions wherein the material layer conveyed is cut by means of mechanical limiting surfaces.

[0012] The idea of an embodiment of the invention is to adjust not only the inclination of ascent but also the speed of the conveyor belt for adjusting the thickness of the material layer. By adjusting the inclination of ascent and the speed of the belt, the thickness of the material layer can be effectively affected.

[0013] The idea of an embodiment of the invention is to adjust the inclination of ascent and the speed of the belt for adjusting the capacity of the feed conveyor. In this case, the capacity may be arranged to be adjusted on the basis of the capacity of the crusher or another device subsequent to the feed conveyor. For example, the feed capacity required by the crusher may be determined on the basis of the amount of material in the feed opening.

[0014] The idea of an embodiment of the invention is to also control the position of the material flow falling off the conveyor belt in the discharge station at the falling point and to adjust the position of the falling point by displacing the feed conveyor in the longitudinal direction.

[0015] The idea of an embodiment of the invention is that the feed conveyor comprises at least one measuring device for determining the thickness of the material layer conveyed.

[0016] The idea of an embodiment of the invention is that the crusher unit comprises a dropping station, whose location is predetermined as preferable from the point of view of the operation of the crusher unit. Furthermore, at least one measuring device is arranged in connection with the feed opening for determining the position of the falling point of the material flow falling off the feed conveyor relative to the dropping station. The operation of the feed conveyor may be controlled by means of a control unit arranged to adjust the feed conveyor in the longitudinal direction by means of a displacing device for setting the falling point at the dropping station determined.

[0017] The idea of an embodiment of the invention is that the feed conveyor comprises one or more lifting feet, owing to which the feed conveyor can be driven from a transport position to a working position and vice versa. The lifting foot comprises a link mechanism by the action of which the discharge station of the feed conveyor is displaced from the transport position to the working position during upward displacement and simultaneously the entire conveyor is displaced forward, observed in the longitudinal direction. Furthermore, by the action of the lifting foot, the discharge station of the feed conveyor is displaced from the working position to the transport position when driving

downward and, at the same time, the entire conveyor is displaced backward, observed in the longitudinal direction. In this manner, the discharge station of the conveyor can be driven above the crusher unit in the working position and, on the other hand, to the side thereof in the transport position.

BRIEF DESCRIPTION OF THE FIGURES

[0018] Some embodiments of the invention will be described in more detail in the accompanying drawings, in which

Figure 1 schematically shows a side view of a crusher according to the invention,

Figure 2 schematically shows the controlling principles associated with the driving of a crusher according to the invention,

Figure 3 schematically shows a side view of a feed conveyor according to the invention in a working position,

Figure 4 schematically shows a side view of a feed conveyor according to the invention in a transport position,

Figure 5 schematically shows a side view of a lifting foot of a feed conveyor according to the invention in a working position,

Figure 6 schematically shows the lifting foot of Figure 5 in a transport position,

Figures 7 and 8 schematically show a side view of the operation, of an inclination adjustment mechanism in a lifting foot, and

Figure 9 schematically shows a detail of a lifting foot.

[0019] In the figures, some embodiments of the invention are shown in a simplified manner for the sake of clarity. In the figures, similar parts are denoted with the same reference numerals.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

[0020] Figure 1 shows a crusher 1 , which may comprise a movable carrier 2, a feed conveyor 3, a crusher unit 4 and a discharge conveyor 5. The feed conveyor 3 is used to transfer material M to be processed, such as rock material, for example, into a feed opening 6 in the crusher unit 4, from where it is conveyed forward to crusher members 7 that crush the material into a smaller particle size. The crusher members 7 may be composed of an eccentrically rotating vertical crusher cone and a crusher chamber surrounding it, for example, whereby the material processed falls into a wedge-like space between the cone and the chamber and is crushed into smaller particles. After

processing, the material falls onto a discharge conveyor 5 below the crusher unit 4, by means of which the material processed may be conveyed to a suitable discharge site 8, for example into a pile 9.

[0021] The feed conveyor 3 comprises two or more pulley drums 10, 11 , around which is arranged a conveyor belt 12 in the shape of a closed loop. At least one pulley drum 10 is a so-called drive pulley, which is rotated by means of a driving motor 13 and necessary power transmission members around its longitudinal axis. The pulley drum 11 , to which no turning force is transmitted, is a so-called return pulley, at which the conveyor belt 12 changes travel directions. The drive pulley and the pulley drum may be arranged in the manner shown in Figure 1 or alternatively they may be arranged conversely relative to each other. The portion above the feed conveyor 3 is provided with a transport section 14, wherein the conveyor belt 12 runs in a conveying direction A. The portion below the feed conveyor 3 is provided with a return section 15, wherein the conveyor belt 12 runs in a return direction B. The transport section 14 is provided with a feed station 16, wherein the material conveyed is fed onto the movable upper surface of the conveyor belt 12. The material is discharged from the transport section 14 at a discharge station 17. The feed station 16 may comprise a feed funnel 18 into which the material to be conveyed may be fed by means of another conveyor or a wheel loader, for example. The lower surface of the conveyor belt 12 may be supported at the transport section 14 by means of a plurality of support rolls 19 and so-called impact bars.

[0022] In Figure 1 , the feed conveyor 3 is shown in the working position, wherein it is positioned into an inclined position such that the feed station 16 is preferably relatively low from the point of view of material feeding, and, on the other hand, the material conveyed can be dropped from the discharge station 17 to the feed opening 6 located at the upper part of the crusher unit 4. With the feed conveyor 3 in the working position, in the transport section 14, the conveyor belt 12 is at an inclination of ascent C relative to the horizontal plane. The inclination of ascent C of rock material, for example, is typically about 20°. One or more lifting devices 20 may be arranged in connection with the feed conveyor 3, with which the inclination of ascent C may be adjusted by moving the end of a body 21 of the feed conveyor 3 on the side of the discharge station 17 in direction D. The lifting device 20 may be a mechanical power member, such as a suitable screw mechanism, for example, or it may

be an actuator, such as a pressure medium-driven or electronic actuator, for example. The end of the body 21 on the side of the feed station 16 may comprise one or more turning links 22, in relation to which the feed conveyor 3 may be turned.

[0023] Furthermore, one or more displacing devices 23 may be arranged in connection with the turning link 22 for displacing the feed conveyor 3 in the longitudinal direction. The longitudinal adjustment of the feed conveyor 3 allows the falling point 24 of the material discharged from the conveyor to be affected, as illustrated in the figure with a dotted broken line. The crusher unit 4 may comprise a pre-designed dropping station, the aim being to set the falling point 24 at said position by displacing the feed conveyor 3. The dropping station may be selected preferably from the point of view of the crushing process and the durability of the crusher members 7. At its simplest, the displacing device 23 is a mechanical power member, such as a screw mechanism, an eccentric or the like, for example. On the other hand, the displacing device 23 may be a pressure medium-driven actuator, such as a hydraulic cylinder, for example. The displacing device 23 may be arranged to move the turning link 22 or, alternatively, the body 21 of the feed conveyor 3 may be fixed by means of the sliding mechanism 26 shown in Figures 3 and 4 to the turning link 22, whereby the longitudinal movement E takes place between the body 21 and the sliding mechanism 26.

[0024] The crusher 1 may comprise one or more control units 27 for affecting the operation of at least the feed conveyor 3. The control unit 27 may comprise manual control members for affecting the driving motor 13, the lifting device 20 and the displacing device 23. If the lifting device 20 and the displacing device 23 are mechanical power members, they are naturally manually adjusted without the control unit 27. On the other hand, the control unit 27 may be arranged to automatically control the operation of the feed conveyor 3 in accordance with a control strategy set therefor. In this case, the control unit 27 may comprise for instance a programmable logic or a processor for executing a computer program for achieving the desired controlling actions.

[0025] In accordance with the idea of the invention, the thickness P of the material layer 28 conveyed on the transport section 14 is affected by adjusting at least the inclination of ascent C of the feed conveyor 3. The thickness P of the material layer 28 may be adjusted to be 300 to 400 mm, for example. By increasing the inclination of ascent C, attempts may be made to re-

duce the thickness P of the material layer and, on the other hand, by reducing the inclination of ascent C, attempts may be made to increase the thickness P. A basic setting for the inclination of ascent C of the feed conveyor 3 may be 20°, for example, and it may be adjusted for instance within the range 18° to 25°. The purpose is for the stationary surfaces 29 above the transport section 14 not to be in contact with the material layer 28 conveyed; instead, the thickness of the material layer 28 is adjusted by adjusting the control parameters of the feed conveyor 3. The manner in which the material conveyed is batched at the feed station 16 onto the conveyor belt 12 depends on internal frictions in the material, friction between the conveyor belt 12 and the material and environmental conditions, for example. In addition to the inclination of ascent C, the speed V of the conveyor belt 12 may also be adjusted. When the desire is to drive the conveyor at constant capacity, the following principie may be observed in the control: The higher the speed V of the conveyor belt 12, the smaller is the thickness of the material layer 28, and vice versa. As driving motor 13, a hydraulic motor, for example, can be used, whose speed of rotation may be adjusted in a stepless manner.

[0026] Figure 2 illustrates actions associated with adjusting the thickness P of the material layer 28 to be conveyed. The transport section 14 of the feed conveyor 3 may comprise one or more measuring devices 30 by means of which the thickness P of the material layer 28 on the conveyor beit 12 can be determined. The operation of the measuring device 30 may be based on a photocell, laser, ultrasound, for example, or another non-contacting measurement can be applied to the measuring device. Figure 2 shows a solution wherein the measuring device comprises a transmitter 30a for instance for transmitting a ray of light 31 transversely to the feed conveyor 3, and further a receiver 30b for receiving said ray of light 31. The transmitter 30a and the receiver 30b may be adapted to a predetermined reference height, whereby a material layer 28 having a thickness P larger than said reference height prevents the passage of a ray of light or the like, and on the basis of this information the inclination of ascent C can be increased and, if need be, the speed V of the conveyor may also be increased to reduce the thickness of the material layer 28. When required, a plurality of measuring devices 30 may be used, and measuring devices 30 may be arranged on at least two different reference heights, whereby the attempt is to keep the thickness P of the material layer between the upper and lower limits. Alternatively, the measuring device 30

may be a device 30c that measures the thickness of the material layer 28 and arranged for instance in the structures 31 above the transport section 14. For example, the measuring device 30c may be a laser distance measuring device, an ultrasound radar or the like. The measuring device 30 may be connected to data transfer means 32, by means of which the measurement data can be transferred to the control unit 27. As mentioned above, the control unit 27 may process the measurement data in accordance with the control strategy given thereto, and may further adjust the control parameters of the feed conveyor 3 for controlling the operation of at least the lifting device 20 and the driving motor 13.

[0027] Alternatively, the operation of the feed conveyor 3 is controlled manually by an operator 33. The operator 33 may visually observe the thickness P of the material layer 28 on the transport section and adjust the lifting device 20 by a manual first control unit 27a and the driving motor 13 by means of a manual second control unit 27b to adjust the thickness P of the material layer 28 as desired.

[0028] Figure 2 also illustrates actions associated with the adjustment of the position of the falling point 24. One or more measuring devices 34 may be provided in connection with the feed opening 6 of the crusher unit 4 for determining the position of the material flow dropping from the discharge station 17. The crusher unit 4 may comprise a pre-designed dropping station 35, into which the falling material flow would preferably be made to fall in view of the operation and durability of the device. In case of a so-called gyratory or cone crusher, the dropping station 35 may be located at the vertical axis of the crusher cone. The measuring device 34 may comprise for instance transmitters 34a, 34c and receivers 34b, 34d for determining if the falling point 24 is located between the limits 35a and 35b determined by the measuring devices. Alternatively, a measuring device 34e for measuring the location of the falling point, such as a laser distance measurement device, an ultrasound radar or the like non-contacting measuring device, for example, may be used. The measurement data may be transferred by means of the data transfer means 32 to the control unit 27, which may adjust the displacing device 23 in accordance with the control strategy set therein. The feed conveyor 3 may be displaced in the longitudinal direction in such a manner that the falling point 24 is at the desired point in the feed opening.

[0029] Alternatively, the falling point 24 may be manually observed

by an operator 33. The operator 33 may visually observe the location of the falling point 24 and, based thereon, use a manual control unit 27c to control the displacing device 23 for adjusting the mutual positions of the feed conveyor 3 and the crusher unit 4.

[0030] It is naturally possible to inform the operator 33 of the measurement results of the measuring devices 30, 34 that observe the operation of the feed conveyor 3, and the operator may utilize the measurement data in controlling the operation of the feed conveyor 3.

[0031] The processing capacity of the crusher unit 4 at each particular time may be determined by estimating the amount of material in the feed opening 6. The measuring device 34e may be arranged to measure the height of the surface, the thickness of the material layer or alternatively the operator may estimate the required material to be fed to the crusher unit 4. Based on this, the capacity of the feed conveyor 3 may be adjusted, i.e. the inclination of ascent C and the belt speed may be adjusted. Other manners of determining the need for material flow to be fed to the crusher unit 4 may naturally be used.

[0032] In Figure 3, the feed conveyor 3 is in an inclined working position and in Figure 4, it is driven into a substantially horizontal transport position. The feed conveyor 3 may be supported to the portion of the back body 2a of the carrier 2. The back body 2a may comprise a support 2b against which the feed conveyor 3 may be arranged in the transport position. The end of the feed conveyor 3 on the side of the discharge station 17 may comprise a lifting foot 36 for displacement from the transport position to the working position and vice versa. One or more first lifting devices 37 are arranged in connection with the lifting foot 36. The lifting foot 36 comprises a link mechanism, owing to which the feed conveyor 3 is displaced into different positions in such a manner that when driving takes place from the transport position to the driving position, the discharge station 17 is displaced upwards and simultaneously the entire conveyor is displaced forward towards the crusher unit 4. This allows the discharge station 17 to be driven above the feed opening 6. When the feed conveyor 3 is displaced from the working position to the transport position to the carrier 2, the discharge station 17 of the conveyor is displaced downward and simultaneously the entire conveyor is displaced backward. The displacing device 23 may be disconnected during the time when the conveyor 3 is driven to the different positions. In case of a mechanical displacing device 23, such as a turnbuckle screw shown in Figures 3 and 4, for example, it may be detached

for the duration of the displacements and reconnected when the conveyor is driven to the working position. Accordingly, the feed conveyor 3 is allowed to move during the displacements in its longitudinal direction by means of a sliding mechanism 26 between the carrier 2 and the conveyor body 21. On the other hand, the displacing device 23 may be arranged in such a manner that it enables a longitudinal movement of the conveyor during the displacements. As is seen in Figure 4, the lifting foot 36 may be bent under the conveyor 3 in the transport position owing to its link system. The first lifting device 37 in connection with the lifting foot 36 may be intended only for displacements between the transport position and the working position, or alternatively, in some cases, it may be used also for adjusting the inclination of ascent C. However, the lifting foot 36 may be provided with an inclination adjustment mechanism 38, which may include one or more second lifting devices 39 for adjusting the inclination of ascent C. The operation and structure of the lifting foot 36 will be explained in more detail in connection with Figures 5 to 9.

[0033] The feed station 16 may comprise one or more feed supports 40 including one or more beams arranged at a distance from the conveyor belt. The feed support 40 may comprise one or more beams in the longitudinal direction of the conveyor and one or more transverse beams. The feed support 40 may carry part of the load of the material in the feed station 16 and it may thus facilitate the batching carried out in the feed station 16.

[0034] Figure 5 shows, for the sake of clarity, only the lifting foot 36 in a position corresponding to the working position, and in Figure 6 in a position corresponding to the transport position. The lifting foot 36 may comprise a turning beam 41 whose first end is coupled with a first link 42 to a support 43 or the carrier 2. The latter alternative is marked with a broken line in Figure 5. Furthermore, the second end of the turning beam 41 comprises a second link 44, to which a first end of a support arm 45 belonging to the inclination adjustment mechanism 38 may be coupled. The second end of the support arm 45 may be coupled by means of a third link 46 to the body of the feed conveyor. Furthermore, the second lifting device 39 is coupled to the section of the first end of the support arm 45. Such lifting feet 36 may be arranged on both sides of the feed conveyor. The lifting feet 36 may be interconnected with a transverse support 47. The first lifting device 37 may be coupled to the transverse support 47 in a manner allowing the lifting feet 36 to be driven with one common lifting device 37.

[0035] The first link 42 of the turning beam 41 is preferably arranged at the height of the feed conveyor when in the transport position by means of a vertical support 43, for example. In this case, the turning beam 41 , the transverse support 47 and the inclination adjustment mechanism 38 may turn between the feed conveyor and the carrier. Accordingly, in the transport position, the feed conveyor is relatively flat and thus enables conventional road transports.

[0036] In Figure 7, the lifting foot 36 is driven to an upper position and the second lifting devices 39 on both sides of the feed conveyor, preferably hydraulic cylinders, are driven to their upper position for adjusting the inclination of ascent C. When the second lifting devices 39 are being used, the support arm 45 is allowed to turn relative to the links 44 and 46. In Figure 8, the second lifting device 39 is driven into its lowest position. In this solution, the inclination of ascent C is thus adjusted only by means of the second lifting devices 39.

[0037] Figure 9 shows a transverse support 47, by means of which the turning beams 41 of the lifting feet on the different sides of the conveyor are interconnected. The first lifting device 37 is coupled to a transverse beam 49 by means of a first fixing lug 48a and a second fixing lug 48b. In this case, one lifting device 37 is sufficient for moving both lifting feet 36. Naturally, more than the first lifting devices 37 can be used. The fixing lugs 48a, 48b may be coupled rotationally relative to one another by means of a link 50. When the feed conveyor is displaced in the longitudinal direction, the fixing lugs 48a, 48b may move relative to one another. At the same time, the second fixing lug 48b may turn around a link 51 at the fixing point of the lifting device 37. When the conveyor is being displaced to the right in Figure 9 by means of the displacing device 23, the second fixing lug 48b turns clockwise in direction G denoted in the figure, which enables the displacement of the discharge station of the feed conveyor in a curved direction H denoted in the figure. Accordingly, the lifting foot 36 turns relative to the link 43 and the discharge station is simultaneously displaced forward and upward. The magnitude of the upward displacement can be affected by the dimensions of the lugs 48. In the above-described series of events, the lifting device 37 is not used. In the position shown in Figure 9, the second fixing lug 48b is against the lower surface of the transverse beam 49, whereby a force can be transferred to the transverse beam 49 by using the lifting device 37 for turning the lifting foot 36 relative to the link 43. In the situa-

tion shown in Figure 9, the fixing lug 48b cannot turn anticlockwise, even if it were affected by the force of the lifting device 37.

[0038] Let it be mentioned that for the sake of security, the feed station of the feed conveyor according to the invention may be provided with an opening, a boom or the like means for limiting the feed of material. However, limiters are only employed in special occasions, such as in connection with conveyor failure and malfunction.

[0039] In some cases, the features presented in the present application can be used as such, irrespective of other features. On the other hand, when required, the features presented in the present application can be combined to form various combinations.

[0040] The drawings and the related description are only intended to illustrate the idea of the invention. The details of the invention may vary within the scope of the claims.