Patent Description:
In road construction, it is common to use pavers to build at least portions of the road, in particular a basic layer and a topcoat of the road. A paver generally comprises a self-propelled tractor with a front hopper adapted to receive and store material, such as asphalt. At the bottom of the hopper, a scraper type of conveyor belt transports the material to the back of the machine. There, the material is spread out by one or more augers. A screed is positioned behind the one or more augers to thereby flatten and level the material and compact the layer using vibration and tamper drives. When a paver travels for the purpose of carrying out a road finishing operation, the paving screed is in a levelling position at which it rests on the road surface layer and carries out movements relative to a chassis of the paver.

<CIT> discloses a paver with a pair of rear wheels and a set of fore-wheels. The paver illustrated in <CIT> further comprises a screed located rearwards of the pair of rear wheels, as seen in an intended direction of travel of the <CIT> paver. During a paving operation, the screed is generally in contact with the ground resulting in that a normal force is imparted on the screed, as consequence of which the pair of rear wheels, as well as the set of fore-wheels, are loaded in an appropriate manner.

However, in a transport operation, the screed may be raised such that it loses ground contact and this may in turn result in that the weight of the screed will be imparted on the paver rather than on the ground. Since the screed is located rearwards of the pair of rear wheels, the pair of rear wheels will in such a situation be imparted a relatively large load whereas the set of fore-wheels will generally be imparted a relatively low load. Such a load distribution between the pair of rear wheels and the set of fore-wheels may result in an undesired dynamic behaviour of the paver. For instance, during a transport operation, the paver may oscillate e.g. vertically or around a transversely extending axis.

As such, it would be desirable to improve the motion characteristics of the above-mentioned paver.

An object of the invention is to provide a paver that has appropriate motion characteristics during at least a transport mode of the paver. The object is achieved by a paver according to claim <NUM>.

As such, the present invention relates to a paver comprising a main vehicle body. The paver comprises a set of fore-wheels. The set of fore-wheels is connected to the main vehicle body via a hydraulic wheel suspension system which, in at least a paving mode of the paver, allows hydraulic level compensation for each wheel of the set of fore-wheels.

As used herein, the expression "hydraulic level compensation" is intended to encompass each wheel of the set of fore-wheels being directly or indirectly hydraulically connected so that the wheel loads are compensated for and substantially identical. A hydraulic level compensation may also be used for setting a desired distance between the set of fore-wheels and the main vehicle body.

According to the present invention, the paver further comprises a hydraulic motion control assembly adapted to selectively provide hydraulic spring suspension and preferably also hydraulic dampening to at least one wheel, preferably at least two wheels, of the set of fore-wheels.

The above-mentioned hydraulic motion control assembly, which may be adapted to selectively provide hydraulic spring suspension and preferably also hydraulic dampening, implies that the paver motions may be suspended and preferably also dampened in an appropriate manner.

Moreover, owing to the fact that the above-mentioned hydraulic spring suspension and preferably also hydraulic dampening can be selectively provided, the paver according to the present invention may be appropriately suspended and preferably also dampened when required, for instance during a transport operation.

To this end, it should be noted that, during a paving operation, it may be desired to provide substantially no hydraulic spring suspension or hydraulic dampening to the set of fore-wheels, since such suspension or dampening may impair the result of the paving operation. Again, the above-mentioned ability to selectively provide hydraulic spring suspension and preferably also hydraulic dampening implies that the hydraulic spring suspension and preferably also hydraulic dampening need not be applied during for instance a paving operation.

Consequently, the paver according to the present invention implies that appropriate motion characteristics can be obtained for a paving operation as well as another type of operation, such as a transport operation, of the paver.

Optionally, the set of fore-wheels comprises a pair of front fore-wheels and a pair of back fore-wheels, as seen in an intended forward direction of travel of the paver. The hydraulic motion control assembly is adapted to selectively provide hydraulic spring suspension and preferably also hydraulic dampening to at least each wheel of the pair of back fore-wheels.

The hydraulic spring suspension and preferably also hydraulic dampening of at least each wheel of the pair of back fore-wheels implies appropriate motion characteristics of the paver, for instance during a transport operation.

Optionally, the hydraulic motion control assembly comprises a hydraulic accumulator. A hydraulic accumulator may be an appropriate means for providing at least hydraulic spring suspension.

Optionally, the hydraulic motion control assembly comprises a throttling arrangement, preferably a throttling valve, in fluid communication with the hydraulic accumulator. A throttling arrangement may be an appropriate means for providing at least hydraulic dampening.

Optionally, the hydraulic wheel suspension system comprises a plurality of cylinders with a cylinder associated with each wheel of the set of fore-wheels, each cylinder having a piston side and a piston rod side. Such a hydraulic wheel suspension system implies appropriate motion characteristics during for instance a paving operation since it implies a possibility to implement hydraulic level compensation in a straightforward manner.

Moreover, owing to the fact that the hydraulic wheel suspension system comprises a plurality of cylinders implies that the hydraulic motion control assembly may be associated with at least one wheel of the set of fore-wheels without the need for necessarily excessive modification of the hydraulic wheel suspension system.

Optionally, the hydraulic motion control assembly comprises a first hydraulic accumulator selectively, preferably via a first selector valve, in fluid communication with the piston side of the cylinder associated with a first wheel of the pair of back fore-wheels and a second hydraulic accumulator selectively, preferably via a second selector valve, in fluid communication with the piston side of the cylinder associated with a second wheel of the pair of back fore-wheels.

The above implementation of the hydraulic motion control assembly implies that the pair
of back fore-wheels by be suspended substantially individually which in turn implies an improved lateral stability of the paver, for instance during transport of the paver.

Optionally, the piston side of the cylinder associated with the first wheel and the piston side of the cylinder associated with the second wheel are connected to each other via a back fore-wheels division valve.

Optionally, the back fore-wheels division valve is adapted to assume at least each one of an open condition, allowing fluid communication between the piston sides, and a throttling condition, allowing throttling of fluid flowing between the piston sides.

The back fore-wheels division valve according to the above implies that a throttled fluid communication between the piston sides associated with the back fore-wheels may occur even when the pair of back fore-wheels are substantially individually suspended. Such a throttled fluid communication may compensate for possible pressure differences in the piston sides which may occur if each one of the back fore-wheels is connected to an individual hydraulic accumulator when the back fore-wheels are at different elevations, for instance due to the fact that the paver is located on uneven ground.

Optionally, the hydraulic motion control assembly is selectively in fluid communication with the piston side of each cylinder associated with a wheel of the pair of back fore-wheels.

As such, the hydraulic motion control assembly may be used for suspending and preferably also dampening compressions of each cylinder associated with a wheel of the pair of back fore-wheels.

Optionally, the hydraulic motion control assembly further is selectively in fluid communication with the piston side of each cylinder associated with a wheel of the pair of front fore-wheels. The above fluid communication may further improve the motion characteristics of the paver during at least a transport operation.

Optionally, the paver further comprises an additional hydraulic motion control assembly adapted to be selectively in fluid communication with the piston rod side of each cylinder associated with a wheel of the pair of front fore-wheels, the additional hydraulic motion control assembly preferably comprising an additional accumulator and/or an additional throttling arrangement.

The additional hydraulic motion control assembly may further improve the suspension and/or dampening of the paver. For instance, during braking of the paver, each cylinder associated with a wheel of the pair of front fore-wheels is generally compressed and, in such a scenario, it may be desired to provide hydraulic suspension and/or hydraulic damping to such compression since it may improve the longitudinal stability of the paver.

Optionally, the hydraulic motion control assembly is further selectively in fluid communication with the piston rod side of each cylinder associated with a wheel of the pair of front fore-wheels. As such, the hydraulic motion control assembly may suspend and preferably also dampen an extension of each cylinder associated with a wheel of the pair of front fore-wheels.

Optionally, the piston side of at least each cylinder associated with a front fore-wheel is selectively in fluid communication with a hydraulic tank, preferably via a tank throttling arrangement.

Optionally, the hydraulic motion control assembly is adapted to be in fluid communication with the hydraulic wheel suspension system via a selector valve. The selector valve is a cost-efficient implementation for selectively and fluidly connecting the hydraulic motion control assembly to the hydraulic wheel suspension system
Optionally, the hydraulic wheel suspension system comprises an equalising line fluidly connecting at least the piston side of the cylinders associated with each wheel of the set of fore-wheels, the hydraulic motion control assembly being adapted to be in fluid communication with the equalising line via the selector valve.

Optionally, the selector valve is adapted to assume a closed condition, preventing fluid communication between the hydraulic wheel suspension system and the hydraulic motion control assembly, the selector valve further being adapted to assume an open condition, allowing fluid communication between the hydraulic wheel suspension system and the <NUM> hydraulic motion control assembly.

Optionally, the paver comprises a screed adapted to be in a lowered position in the paving mode and in a raised position in the non-paving mode, the selector valve being adapted to assume the closed condition when the screed is in the lowered position and adapted to assume the open condition when the screed is in the raised position.

Optionally, each wheel of the set of fore-wheels is a solid material wheel. Solid material wheels imply that the wheels can be relatively small, as a consequence of which the volume of the loading area, such as a hopper, of the paver can be relatively large.

Optionally, the paver further comprises a pair of rear wheels connected to the main vehicle body, preferably the pair of rear wheels being adapted to propel the paver.

Optionally, the pair of rear wheels comprises pneumatic tires.

A second aspect of the present disclosure relates to a method for operating a paver according to claim <NUM>. The paver comprises a main vehicle body. The paver comprises a set of fore-wheels. The set of fore-wheels is connected to the main vehicle body via a hydraulic wheel suspension system. The paver is operable in at least each one of a paving mode and a non-paving mode. As has been intimated hereinabove, a non-paving mode may for instance be a transport mode.

The method according to the second aspect of the present invention comprises:.

Optionally, the set of fore-wheels comprises a pair of front fore-wheels and a pair of back fore-wheels, as seen in an intended forward direction of travel of the paver, the method comprising:.

Optionally, the method further compirses:.

Optionally, the hydraulic motion control assembly is adapted to be in fluid communication with the hydraulic wheel suspension system via a selector valve. The step of providing the hydraulic spring suspension and preferably also the hydraulic dampening comprises arranging the selector valve in an open condition, allowing fluid communication between the hydraulic wheel suspension system and the hydraulic motion control assembly.

Optionally, the paver comprises a screed adapted to be moveable relative to the main vehicle body, the method comprising detecting the position of the screed relative to the main vehicle body and:.

Optionally, the paver comprises the features of any one of the above-mentioned alternatives of the first aspect of the present invention.

A third aspect of the present invention relates to an electronic control unit for a paver according to claim <NUM>. The paver comprises a main vehicle body. The paver comprises a set of fore-wheels. The set of fore-wheels is connected to the main vehicle body via a hydraulic wheel suspension system which, in at least a paving mode of the paver, allows hydraulic level compensation for each wheel of the set of fore-wheels, the paver further comprising a hydraulic motion control assembly adapted to selectively provide hydraulic spring suspension and/or hydraulic dampening to at least one wheel, preferably at least two wheels, of the set of fore-wheels.

The electronic control unit is adapted to.

Optionally, the set of fore-wheels comprises a pair of front fore-wheels and a pair of back fore-wheels, as seen in an intended forward direction of travel of the paver, wherein the electronic control unit further is adapted to:.

Optionally, the electronic control unit further is adapted to.

Optionally, the hydraulic motion control assembly is adapted to be in fluid communication with the hydraulic wheel suspension system via a selector valve. The feature of issuing a control signal to the paver so as to provide the hydraulic spring suspension and/or the hydraulic dampening comprises issuing a signal to the selector valve to assume an open condition, allowing fluid communication between the hydraulic wheel suspension system and the hydraulic motion control assembly.

Optionally, the paver comprises a screed adapted to be moveable relative to the main vehicle body, the electronic control unit being adapted to receive a signal indicative of the position of the screed relative to the main vehicle body, and determining that the paver is operating in the paving mode upon detection that the screed is in a lowered position, and determining that the paver is operating in the non-paving mode upon detection that the screed is in a raised position.

<FIG> illustrates a paver <NUM> which comprises a main vehicle body <NUM>. Moreover, the paver comprises a set of fore-wheels <NUM>. In the embodiment illustrated in <FIG>, the set of fore-wheels <NUM> comprises a pair of front fore-wheels <NUM> and a pair of back fore-wheels <NUM>, as seen in an intended forward direction of travel of the paver <NUM>. Such an intended direction of travel is indicated by the arrow Lin <FIG>. However, it is also envisioned that other embodiments of the paver <NUM> may comprise other configurations of the set of fore-wheels <NUM>.

Purely by way of example, it is envisioned that embodiments of the paver <NUM> may comprise a set of fore-wheels <NUM> which comprises more than two pairs of fore-wheels (not shown). It is also envisioned that other embodiments of the paver <NUM> may comprise an uneven number of wheels. As non-limiting examples, embodiments of the paver <NUM> may comprise a single front fore-wheel and a pair of back fore-wheels (not shown) or a pair of front fore-wheels and a single back fore-wheel (not shown).

As a non-limiting example, each wheel of the set of fore-wheels <NUM> may be a solid material wheel.

Irrespective of its configuration, the set of fore-wheels <NUM> is connected to the main vehicle body <NUM> via a hydraulic wheel suspension system <NUM> which, in at least a paving mode of the paver <NUM>, allows hydraulic level compensation for each wheel of the set of fore-wheels <NUM>.

Moreover, as may be gleaned from <FIG>, the paver <NUM> may comprise a pair of rear
wheels <NUM> connected to the main vehicle body <NUM>. Purely by way of example, and as is indicated in <FIG>, the pair of rear wheels <NUM> may be adapted to propel the paver <NUM>. As a non-limiting example, the pair of rear wheels <NUM> may comprise pneumatic tires.

<FIG> further illustrates that the paver <NUM> comprises a hopper <NUM> for holding and discharging paving material, such as asphalt, and a screed <NUM> adapted to spread out and flatten the paving material discharged from the hopper <NUM>. The screed <NUM> is adapted to assume a ground contact position, in which the screed <NUM> contacts the ground surface <NUM>, as well as a ground release position, in which the screed <NUM> does not contact the ground surface <NUM>. Generally, the screed <NUM> assumes the ground contact position during a paving mode of the paver <NUM> such that the screed <NUM> can spread out and flatten the paving material discharged from the hopper <NUM> in an appropriate manner.

In order to be able to move the screed <NUM> between the ground contact position and the ground release position, the screed <NUM> is movably connected to the main vehicle body <NUM>.

For instance, and as is exemplified in <FIG>, the screed <NUM> may be connected to the main vehicle body <NUM> via a link arm arrangement <NUM> comprising a link arm <NUM>. The link arm <NUM> is pivotally connected to the main vehicle body <NUM> and is also connected to the screed <NUM>, for instance also pivotally connected to the screed <NUM>. Moreover, the link arm arrangement <NUM> comprises an actuator <NUM>, exemplified as a hydraulic cylinder in <FIG>, for effecting the raising and lowering of the link arm <NUM>, and consequently the screed <NUM>, relative to the main vehicle body <NUM>. Moreover, as is indicated in <FIG>, the link arm arrangement <NUM> may comprise a second actuator <NUM>, located forward of the first actuator <NUM> in an intended direction of travel of the paver <NUM>. The second actuator <NUM> may be used for adjusting the position of the link arm <NUM>, and thus the distance between the screed <NUM> and the ground surface <NUM>, during for instance a paving operation.

Furthermore, the paver <NUM> may comprise a screed sensor <NUM> for detecting whether or not the screed <NUM> is in contact with the ground surface <NUM>. Instead of a link arm arrangement <NUM> such as the one presented hereinabove, it is envisioned that embodiments of the paver <NUM> may comprise another type of arrangement for moving the screed <NUM> relative to the main vehicle body <NUM>. Purely by way of example, embodiments of the paver <NUM> may comprise an arrangement (not shown) for moving the screed <NUM> rectilinearly, for instance <NUM> substantially horizontally, relative to the main vehicle body <NUM>.

As a non-limiting example, the screed sensor <NUM> may be an angle sensor adapted to determine the pivot angle of the link arm <NUM> relative to the main vehicle body <NUM>. As another non-limiting example, the screed sensor <NUM> may be adapted to determine the vertical position of the screed <NUM> relative to the main vehicle body <NUM> and/or relative to the ground <NUM>. As a further non-limiting example, the screed sensor <NUM> may be adapted to determine a contact force between the screed <NUM> and the ground surface <NUM>. As yet another alternative, the screed sensor <NUM> may be adapted to determine a current load configuration of the paver <NUM>.

<FIG> illustrates the paver <NUM> in a condition in which the screed <NUM> is in a ground release position. Since the screed <NUM> generally has a substantial weight and since the screed <NUM> generally is positioned at the far rear of the paver <NUM>, the <FIG> condition will result in that a relatively large part of the paver normal forces will be imparted on the pair of rear wheels <NUM>. Such a normal force scenario is illustrated in <FIG> with large normal forces NR imparted on the pair of rear wheels <NUM> and relatively small normal forces NF imparted on the set of fore-wheels <NUM>. In <FIG>, the difference between the normal forces NR and NF has been exaggerated for the purpose of explanation.

When relatively large forces are imparted on the pair of rear wheels <NUM>, this may result in the paver <NUM> moving in an undesired manner. For instance, the paver <NUM> may oscillate vertically, see arrow <NUM>, and/or around a transversely extending axis <NUM>, see arrow <NUM>.

For instance, such oscillations may be significant if the pair of rear wheels <NUM> comprises pneumatic tires since such pneumatic tires act as a spring, as a result of which the paver <NUM> may have a dynamic behaviour with natural frequencies that may be excited by the loads imparted on the paver <NUM>.

In order to address an undesired motion behaviour, the <FIG> paver <NUM> further comprises a hydraulic motion control assembly <NUM> adapted to selectively provide hydraulic spring suspension and/or hydraulic dampening to at least one wheel, preferably at least two wheels, of the set of fore-wheels <NUM>.

<FIG> schematically illustrates the hydraulic wheel suspension system <NUM> and the hydraulic motion control assembly <NUM> of the <FIG> paver <NUM>. As may be gleaned from <FIG>, the hydraulic wheel suspension system <NUM> illustrated therein comprises a plurality of cylinders <NUM>, <NUM>, <NUM>, <NUM> with a cylinder associated with each wheel <NUM> of the set of fore-wheels, each cylinder having a piston side <NUM>', <NUM>', <NUM>', <NUM>' and a piston rod side <NUM>", <NUM>", <NUM>", <NUM>".

In the <FIG> embodiment, each wheel of the set of fore-wheels <NUM> is individually connected to the main vehicle body <NUM>. Purely by way of example, and as is illustrated in <FIG>, each wheel of the set of fore-wheels <NUM> may be connected to an individual cylinder <NUM>, <NUM>, <NUM>, <NUM> via an individual wheel axle <NUM>, <NUM>, <NUM>, <NUM>.

Moreover, as is indicated in <FIG>, the wheel suspension system <NUM> comprises an equalising line <NUM> fluidly connecting at least the piston side <NUM>', <NUM>', <NUM>', <NUM>' of the cylinders associated with each wheel of the set of fore-wheels. As such, during for instance a paving mode of the <FIG> paver <NUM>, hydraulic fluid may flow between the piston sides <NUM>', <NUM>', <NUM>', <NUM>' thereby allowing hydraulic level compensation for each wheel of the set of fore-wheels <NUM>.

As may be gleaned from <FIG>, the hydraulic motion control assembly <NUM> may comprise a hydraulic accumulator <NUM>. Generally, a hydraulic accumulator may be a pressure storage reservoir in which hydraulic fluid is held under pressure applied by an external source.

Purely by way of example, the external source can be a spring, a raised weight or a compressed gas. As such, a hydraulic accumulator <NUM> generally provides hydraulic suspension to a hydraulic system.

<FIG> further illustrates that the hydraulic motion control assembly <NUM> may comprise a throttling arrangement <NUM>. A throttling arrangement <NUM> generally provides hydraulic damping. Purely by way of example, the throttling arrangement <NUM> may be a fixed throttling. As another non-limiting example, and as is illustrated in the <FIG> embodiment, the throttling arrangement <NUM> may comprise a throttling valve which thus may comprise a variable orifice (not shown). By virtue of a throttling valve, it may be possible to adjust the throttling degree, and thus the hydraulic damping, to a hydraulic system.

As has been intimated hereinabove, the hydraulic motion control assembly <NUM> is adapted to selectively provide hydraulic spring suspension and/or hydraulic dampening to at least one wheel of the set of fore-wheels <NUM>. To this end, the paver <NUM> preferably comprises a selector valve <NUM> for providing selective communication between the hydraulic motion control assembly <NUM> and the relevant cylinder(s). In the <FIG> embodiment, the paver <NUM> further comprises a conduit <NUM> connecting the selector valve <NUM> and the piston side <NUM>' of the cylinder <NUM> associated with one of the pair of back fore-wheels <NUM>.

As such, when the <FIG> selector valve <NUM> assumes a closed condition (such a condition is indicated in <FIG>), fluid communication between the piston side <NUM>' and the hydraulic motion control assembly <NUM> is prevented, and when the <FIG> selector valve <NUM> assumes an open condition, fluid communication between the piston side <NUM>' and the hydraulic motion control assembly <NUM> is enabled.

Although it is envisioned that the hydraulic motion control assembly <NUM> may be used for only one wheel of the set of fore-wheels <NUM>, it is also possible that the hydraulic motion control assembly <NUM> may be used for at least two wheels of the set of fore-wheels <NUM>. To this end, reference is again made to <FIG> illustrating that the piston sides <NUM>', <NUM>' of the cylinders <NUM>, <NUM> associated with a pair of rear wheels <NUM> are connected to one another via a portion <NUM>' of the equalising line <NUM>. As such, in <FIG>, the hydraulic motion control assembly <NUM> is adapted to selectively provide hydraulic spring suspension and/or hydraulic dampening to at least each wheel of the pair of back fore-wheels <NUM>.

As has been intimated hereinabove, the <FIG> wheel suspension system <NUM> comprises an equalising line <NUM> fluidly connecting at least the piston side <NUM>', <NUM>', <NUM>', <NUM>' of the cylinders associated with each wheel of the set of fore-wheels <NUM>. As such, should it be desired to provide hydraulic spring suspension and/or hydraulic dampening to only the wheels of the pair of back fore-wheels <NUM>, a division valve <NUM> may be used for preventing fluid communication between the cylinders <NUM>, <NUM> associated with each wheel of the pair of front fore-wheels <NUM> and the cylinders <NUM>, <NUM> associated with each wheel of the pair of back fore-wheels <NUM>.

As another example, in the event that it should be desired to provide hydraulic spring suspension and/or hydraulic dampening to only one wheel of the pair of back fore-wheels <NUM>, a division valve <NUM>' (indicated by phantom lines in <FIG>) may be used for preventing fluid communication between the cylinder <NUM> associated with one wheel of the pair of back fore-wheels <NUM> and the cylinders <NUM>, <NUM>, <NUM> of the other wheels in the set of fore-wheels <NUM>. It is also contemplated that embodiments of the paver <NUM> may comprise a plurality of hydraulic motion control assemblies (not shown in <FIG>) wherein each hydraulic motion control assembly is selectively connected to the cylinder of at least one wheel. As a non-limiting example, a first hydraulic motion control assembly may be selectively connected to one or more left hand side wheels of a paver <NUM> and a second hydraulic motion control assembly may be selectively connected to one or more right hand side wheels of a paver <NUM>. Such a configuration may improve the transversal stability of a paver <NUM>, for instance during a transport operation.

As has been indicated herein above, the paver <NUM> may comprise a screed <NUM> adapted to be in a lowered position in the paving mode and in a raised position in the non-paving mode. The selector valve <NUM> may be adapted to assume the closed condition when the screed <NUM> is in the lowered position and adapted to assume the open condition when the screed is in the raised position <NUM>.

In order to control the selector valve <NUM>, for instance employing a control strategy such as the one indicated hereinabove, and possibly also the division valve <NUM>, <NUM> ', should the paver <NUM> comprise such a valve, the paver <NUM> preferably comprises an electronic control unit <NUM>. The electronic control unit <NUM> may be adapted to transmit signals to the selector valve <NUM> indicative of whether the selector valve <NUM> should assume a closed condition or <NUM> an open condition. The electronic control unit <NUM> may also be adapted to transmit similar signals to the division valve <NUM>, <NUM>' should such a valve be present in the paver <NUM>.

The electronic control unit <NUM> may be adapted to determine if the paver <NUM> is operating in the paving mode or in the non-paving mode. To this end, the electronic control unit <NUM> may be in communication with the previously mentioned screed sensor <NUM>. For instance, the electronic control unit <NUM> may be adapted to determine whether or not the screed <NUM> is in contact with the ground surface <NUM> on the basis of one or more signals received from the screed sensor <NUM>. If the electronic control unit <NUM> determines that there is contact between the screed <NUM> and the ground surface <NUM>, the electronic control unit <NUM> may determine that the paver <NUM> is operating in the paving mode. As another example, the electronic control unit <NUM> may be adapted to receive direct input from another component, such as the screed sensor <NUM>, whether or not the paver <NUM> is operating in the paving mode.

Furthermore, the electronic control unit <NUM> may be adapted to receive input from an operator input means <NUM>, such as a lever, button, keyboard, touch screen or the like, via which an operator can issue a signal indicative of the current mode of the paver <NUM>, for instance whether or not the paver <NUM> is operating in the paving mode.

Moreover, the electronic control unit <NUM> may be adapted, upon determination that the paver <NUM> is operating in a non-paving mode, to issue a control signal to the paver <NUM> so as to provide hydraulic spring suspension and/or hydraulic dampening to at least one wheel, preferably at least two wheels, of the set of fore-wheels <NUM> by means of the hydraulic motion control assembly <NUM>. As such, and as is indicated in <FIG>, the electronic control unit <NUM> may be adapted to issue control signals to the selector valve <NUM> and also to the division valve <NUM>, <NUM>' in the event that the paver <NUM> comprises such a division valve.

<FIG> illustrates an alternative to the <FIG> embodiment. In <FIG>, the division valve <NUM> is implemented as a valve having three positions. In the centre position, as shown in <FIG>, the piston side <NUM>', <NUM>', <NUM>', <NUM>' of the cylinders associated with each wheel of the set of fore-wheels <NUM> hydraulically communicate. As such, when the division valve <NUM> assumes the centre position in <FIG>, hydraulic level compensation of the wheels of the set of fore-wheels <NUM> may be obtained.

In the lower position of the division valve <NUM>, the pair of front fore-wheels <NUM> is hydraulically isolated from the pair of back fore-wheels <NUM>. In the upper position of the division valve <NUM>, the pair of front fore-wheels <NUM> can be hydraulically isolated from the pair of back fore-wheels <NUM>. Further, in this upper position, the front pair fore-wheels can be relieved or pressurized. For this purpose, when the division valve <NUM> assumes its upper position in <FIG>, the piston side <NUM>', <NUM>', of each cylinder <NUM>, <NUM> associated with a wheel of the pair of front fore-wheels <NUM> can be connected to a pressure source <NUM>, such as a pump, and a tank <NUM> via a pressure control valve <NUM>.

As such, when the division valve <NUM> assumes its upper position, the pressure in the piston sides <NUM>', <NUM>' can be set by actuating the pressure control valve <NUM>. For instance, the pressure in the piston sides <NUM>', <NUM>' can be reduced or increased, depending on the setting of the pressure control valve <NUM>. In the event that the pressure in the piston sides <NUM>', <NUM>' is reduced by draining fluid to the tank <NUM> during for instance a transport operation of the paver <NUM>, the pressure control valve <NUM> may be actuated such that the pressure source <NUM> increases the pressure in the piston sides <NUM>', <NUM>' before and/or during another type of operation, such as a paving operation.

<FIG> illustrates an alternative to the <FIG> and <FIG> embodiments. As may be realized from <FIG>, the embodiment of the paver disclosed therein is similar to the <FIG> embodiment. Thus, in the below presentation of the <FIG> embodiment, emphasis is put on features present in <FIG> but not present in <FIG>.

As may be gleaned from <FIG>, the implementation of the hydraulic motion control assembly <NUM> disclosed therein comprises a first hydraulic accumulator <NUM>' selectively in fluid communication with the piston side <NUM>' of the cylinder <NUM> associated with a first wheel <NUM>' of the pair of back fore-wheels <NUM>. Purely by way of example, and as indicated in <FIG>, the above selective connection may be achieved by means of a first selector valve <NUM>'.

As indicated in <FIG>, the first selector valve <NUM>' may preferably be adapted to assume at least each one of an open condition, allowing fluid communication between the first hydraulic accumulator <NUM>' and the piston side <NUM>', and a closed condition, preventing fluid communication between the first hydraulic accumulator <NUM>' and the piston side <NUM>'. Purely by way of example, the first wheel <NUM>' may be the right hand side wheel of the pair of back fore-wheels <NUM>.

Further, the <FIG> the implementation of the hydraulic motion control assembly <NUM> comprises a second hydraulic accumulator <NUM>" selectively in fluid communication with the piston side <NUM>' of the cylinder <NUM> associated with a second wheel <NUM>" of the pair of back fore-wheels <NUM>. Purely by way of example, and as indicated in <FIG>, the above selective <NUM> connection may be achieved by means of a second selector valve <NUM>".

As indicated in <FIG>, the second selector valve <NUM>" may preferably be adapted to assume at least each one of an open condition, allowing fluid communication between the second hydraulic accumulator <NUM>" and the piston side <NUM>', and a closed condition, preventing fluid communication between the second hydraulic accumulator <NUM>" and the piston side <NUM>'. Purely by way of example, the second wheel <NUM>" may be the left hand side wheel of the pair of back fore-wheels <NUM>.

Thus, the first and second wheels <NUM>', <NUM>" of the back fore-wheels <NUM> may be substantially individually suspended in the <FIG> embodiment. Moreover, though purely by way of example, the paver <NUM> may be such that the piston side <NUM>' of the cylinder <NUM> associated with the first wheel <NUM>' and the piston side <NUM>' of the cylinder <NUM> associated with the second wheel <NUM>" are connected to each other via a back fore-wheels division valve <NUM>'. Such an implementation is indicated in <FIG>.

Further, as indicated in <FIG>, the back fore-wheels division valve <NUM>' may preferably be adapted to assume at least each one of an open condition (see the right portion of the back fore-wheels division valve <NUM>' illustrated in <FIG> ), allowing fluid communication between the piston sides <NUM>', <NUM>', and a throttling condition (see the left portion of the back fore-wheels division valve <NUM>' illustrated in <FIG> ), allowing throttling of fluid flowing between the piston sides <NUM>', <NUM>'.

Purely by way of example, the back fore-wheels division valve <NUM>' may comprise a first smallest orifice with a first orifice cross-sectional area through which fluid flows when the valve <NUM> 'is in the open condition and the back fore-wheels division valve <NUM>' may also comprise a second smallest orifice with a second orifice cross-sectional area through which fluid flows when the valve <NUM>' is in the throttling condition. As a non-limiting example, the second orifice cross-sectional area may be within the range of <NUM>% to <NUM>%, preferably within the range of <NUM> % to <NUM> % of the first orifice cross-sectional area.

As a non-limiting example, in the condition illustrated in <FIG>, the division valve <NUM> is in the centre position and the back fore-wheels division valve <NUM>' assumes the open condition, as a result of which the piston side <NUM>', <NUM>', <NUM>', <NUM>' of the cylinders associated with each wheel of the set of fore-wheels <NUM> hydraulically communicate. As such, hydraulic level compensation of the wheels of the set of fore-wheels <NUM> may be obtained.

The illustrated conditions of the valves <NUM>, <NUM>' may be preferred for a paver in a paving condition. In such a condition, each one of the first and second selector valves <NUM>', <NUM>" may assume its closed condition.

On the other hand, in a transport condition for instance, the division valve <NUM> preferably prevents fluid communication between the piston sides <NUM>', <NUM>' and the piston sides <NUM>', <NUM>'. For instance, the division valve <NUM> may assume the top position illustrated in <FIG>.

Moreover, in a transport condition, each one of the first and second selector valves <NUM>', <NUM>" may assume its open condition and the back fore-wheels division valve <NUM>' may assume its throttling condition.

When the valves <NUM>', <NUM>", <NUM>, <NUM>' are in the above-mentioned conditions, the wheels <NUM>', <NUM>" of the pair of back fore-wheels <NUM> are substantially individually suspended. However, owing to the fact that the back fore-wheels division valve <NUM>' is in its throttling condition, a limited fluid communication is allowed between the piston sides <NUM>', <NUM>'. Such a limited fluid communication may be beneficial if the wheels <NUM>', <NUM>" for instance are located on different elevations when the suspension is activated. Purely by way of example, different elevations may occur if the paver is located on uneven ground when the suspension is activated. In such a situation, the throttling via the back fore-wheels division valve <NUM>' implies that the wheels <NUM>', <NUM>" may eventually be located on substantially the same elevation since the pressure differences in the piston sides <NUM>', <NUM>' may be levelled out.

<FIG> and <FIG> illustrate another embodiment of the paver <NUM>. The <FIG> and <FIG> embodiment comprises a plurality of features corresponding to similar features in the <FIG> and <FIG> embodiment, which features are assigned the same reference numerals but are generally not elaborated on again hereinbelow. In the <FIG> and <FIG> embodiment, the hydraulic motion control assembly <NUM> is further selectively in fluid communication with the piston side <NUM>', <NUM>', of each cylinder <NUM>, <NUM> associated with a wheel of the pair of front fore-wheels <NUM>.

As such, in the <FIG> and <FIG> embodiment, the hydraulic motion control assembly <NUM> is adapted to selectively provide hydraulic spring suspension and/or hydraulic dampening to all wheels of the set of fore-wheels <NUM>. To this end, in the <FIG> and <FIG> embodiment, the hydraulic motion control assembly <NUM> is adapted to be in fluid communication with the <NUM> above-mentioned equalising line <NUM> via the selector valve <NUM> and the <FIG> equalising line <NUM> may for instance be free from a division valve.

As a non-limiting example, and as is indicated in <FIG>, the selector valve <NUM> is adapted to assume a closed condition, preventing fluid communication between the hydraulic wheel suspension system <NUM> and the hydraulic motion control assembly <NUM>. Furthermore, the selector valve <NUM> is adapted to assume an open condition, allowing fluid communication between the hydraulic wheel suspension system <NUM> and the hydraulic motion control assembly <NUM>.

As for the <FIG> embodiment, the <FIG> throttling arrangement <NUM> comprises a single throttling valve. However, <FIG> illustrates an embodiment of the paver <NUM> which comprises a throttling arrangement <NUM> which in turn comprises a first throttling valve <NUM> and a second throttling valve <NUM>. Moreover, the <FIG> throttling arrangement <NUM> comprises a first non-return valve <NUM>, allowing fluid flow in a direction from the selector valve <NUM> to the hydraulic accumulator <NUM> but preventing flow in a direction from the hydraulic accumulator <NUM> to the selector valve <NUM>. Moreover, the <FIG> throttling arrangement <NUM> comprises a second non-return valve <NUM>, allowing fluid flow in a direction from the hydraulic accumulator <NUM> to the selector valve <NUM> but preventing flow in a direction from the selector valve <NUM> to the hydraulic accumulator <NUM>.

The <FIG> throttling arrangement embodiment implies that the throttling of fluid flowing from the selector valve <NUM> to the hydraulic accumulator <NUM> may be different from the throttling for fluid flowing from the hydraulic accumulator <NUM> to the selector valve <NUM>. This in turn implies that the compression and extension of the piston sides <NUM>', <NUM>', <NUM>', <NUM>' may be associated with different throttling levels and thus different damping levels. The ability to have different damping levels for the compression and extension, respectively, of the piston sides <NUM>', <NUM>', <NUM>', <NUM>' implies that the motion characteristics of the paver <NUM> may be controlled in an appropriate manner.

<FIG> and <FIG> illustrates another embodiment of the paver <NUM> which further comprises an additional hydraulic motion control assembly <NUM> adapted to be selectively in fluid communication with the piston rod side <NUM>", <NUM>" of each cylinder <NUM>, <NUM> associated with a wheel of the pair of front fore-wheels <NUM>. Purely by way of example, and as is illustrated in <FIG>, the additional hydraulic motion control assembly <NUM> may comprise an additional accumulator <NUM> and/or an additional throttling arrangement <NUM>. In fact, the <FIG> implementation of the additional hydraulic motion control assembly <NUM> comprises an additional accumulator <NUM> as well as an additional throttling arrangement <NUM>.

The above-mentioned selective fluid communication between the additional hydraulic motion control assembly <NUM> and the piston rod sides <NUM>", <NUM>" may be achieved by means of an additional selector valve <NUM> located between the piston rod sides <NUM>", <NUM>" and the additional hydraulic motion control assembly <NUM>, as seen in an intended fluid flow direction therebetween. As may be gleaned from <FIG>, the additional selector valve <NUM> may be adapted to assume a first condition, providing fluid communication between the piston rod sides <NUM>", <NUM>" and the additional hydraulic motion control assembly <NUM>, and a second condition, providing fluid communication between the piston rod sides <NUM>", <NUM>" and a tank <NUM>. The additional selector valve <NUM> may be adapted to receive signals from the electronic control unit <NUM>.

<FIG> illustrates another embodiment of the present invention in which the hydraulic motion control assembly <NUM> further is selectively in fluid communication with the piston rod side <NUM>", <NUM>" of each cylinder <NUM>, <NUM> associated with a wheel of the pair of front fore-wheels <NUM>.

As such, and as is illustrated in <FIG>, the piston rod side <NUM>", <NUM>" of each cylinder <NUM>, <NUM> associated with a wheel of the pair of front fore-wheels <NUM> may be in selective fluid communication with the piston sides <NUM>', <NUM>' of the cylinders <NUM>, <NUM> associated with the pair of back fore-wheels <NUM>. To this end, the <FIG> embodiment comprises a connection selector valve <NUM> adapted to assume a connection condition, fluidly connecting the piston rod sides <NUM>", <NUM>" to the piston sides <NUM>', <NUM>', and a disconnecting condition, fluidly disconnecting the piston rod sides <NUM>", <NUM>" from the piston sides <NUM>', <NUM>'. The connection selector valve <NUM> may be adapted to receive signals from the electronic control unit <NUM>.

Moreover, the <FIG> embodiment comprises a selector valve <NUM> between the hydraulic motion control assembly <NUM> and the piston sides <NUM>', <NUM>' of the cylinders <NUM>, <NUM> associated with the pair of back fore-wheels <NUM>. As such, when the connection selector valve <NUM> assumes its connection condition and when the selector valve <NUM> assumes its open condition, such valve conditions being illustrated in <FIG>, the fluid communication is provided between the piston rod sides <NUM>", <NUM>", the piston sides <NUM>', <NUM>' and the hydraulic motion control assembly <NUM>.

Moreover, in the embodiment illustrated in <FIG>, the piston side <NUM>', <NUM>' of at least each cylinder associated with a front fore-wheel <NUM> is selectively in fluid communication with a hydraulic tank <NUM>. As is exemplified in <FIG>, the piston side <NUM>', <NUM>' of at least each cylinder associated with a front fore-wheel <NUM> is preferably selectively in fluid communication with a hydraulic tank <NUM> via a tank throttling arrangement <NUM>.

As exemplified in <FIG>, the paver <NUM> may comprise a tank connector valve <NUM> in fluid communication with the piston sides <NUM>', <NUM>' of each cylinder <NUM>, <NUM> associated with a wheel of the pair of front fore-wheels <NUM>. The tank connector valve <NUM> can assume a tank connection condition, providing fluid communication between the piston sides <NUM>', <NUM>' and the tank <NUM>, and a piston side connection condition, providing fluid communication between the piston sides <NUM>', <NUM>', <NUM>', <NUM>'. The tank connector valve <NUM> may be adapted to receive signals from the electronic control unit <NUM>.

When the connector valve <NUM> has assumed the tank connection condition, fluid may have been drained from the piston sides <NUM>', <NUM>' to the tank <NUM>. As such, it may be desired to feed fluid to the piston sides <NUM>', <NUM>' prior to the paver <NUM> performing another type of operation, such as a paving operation. In order to be able to feed fluid to the piston sides <NUM>', <NUM>', the tank <NUM> of the <FIG> embodiment may be replaced by an assembly comprising a pressure source <NUM>, a tank <NUM> and a pressure control valve <NUM>. Such an assembly has been presented hereinabove with reference to <FIG> and the configuration and function of such an assembly is not repeated here. As another option, the connector valve <NUM> may be adapted to assume a third condition, viz a pump connection condition, providing fluid communication between the piston sides <NUM>', <NUM>' and a pump (not shown in <FIG>) such that fluid may be fed to the piston sides <NUM>', <NUM>'.

Claim 1:
A paver (<NUM>) comprising a main vehicle body (<NUM>), said paver (<NUM>) comprising a set of fore-wheels (<NUM>), said set of fore-wheels (<NUM>) being connected to said main vehicle body (<NUM>) via a hydraulic wheel suspension system (<NUM>) which, in at least a paving mode of said paver (<NUM>), allows hydraulic level compensation for each wheel of said set of fore-wheels (<NUM>), said paver (<NUM>) further comprising a hydraulic motion control assembly (<NUM>) characterized in that the hydraulic motion control assembly (<NUM>) is adapted to selectively provide hydraulic spring suspension, and preferably also hydraulic dampening, to at least one wheel, preferably at least two wheels, of said set of fore-wheels (<NUM>).