Self-propelled construction machine

A self-propelled construction machine comprises a machine frame, on which a working unit is arranged, and comprises a drive unit for driving the working unit. An additive, in particular a urea solution for operating an exhaust gas treatment system, is provided in an operating material tank which is integrated in the fuel tank or water tank of the construction machine. The integration of the operating material tank in the fuel tank or water tank does not necessitate any modifications to the machine frame. The dimensions of the construction machine can also remain unchanged, since the fuel tank does not take up any extra space on the machine frame if the dimensions of the fuel tank or water tank are maintained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a self-propelled construction machine, in particular a road milling machine, recycler, stabiliser, finisher or roller, comprising a machine frame, on which a working unit is arranged, and comprising a drive unit for driving the working unit.

2. Description of the Prior Art

In road construction, self-propelled construction machines of different designs are used, including the known road milling machines, recyclers, stabilisers, finishers or rollers. Existing layers of the road surfacing can be removed using the known road milling machines and existing surfaces can be prepared using the recyclers. The stabilisers are used to stabilise soils that do not have sufficient load-bearing capacity, for example for road construction. The finishers are used to build roads, a distinction being drawn between asphalt finishers for laying asphalt and slip form finishers for laying concrete. Rollers are used to compress a wide range of materials in road construction, groundwork, agriculture and landfill construction. Construction machines of this type have a working unit for carrying out the work required for the building operations, which working unit may for example be a working roller, and in particular a milling roller equipped with milling tools in the case of road milling machines, stabilisers and recyclers. The working roller is driven by a drive unit which has at least one internal combustion engine. The fuel for the internal combustion engine, in particular a diesel engine, is provided in a fuel tank, in particular a diesel fuel tank.

Furthermore, it is known that construction machines comprise a water tank for storing service water. This service water is used for example in the known road milling machines in order to ensure that, during the milling process, the milling tools are cooled and thus the service life is increased, or is used in the known rollers in order to remove dirt from the roller lining and thus prevent the work result from being negatively impacted. Along with fuel and water, additional operating materials are also required for the operation of the construction machine. Therefore, in addition to the fuel tank and water tank, the known construction machines also have one or more operating material tanks arranged on the machine frame.

U.S. Pat. No. 2,008,260 461 A1 discloses a self-propelled construction machine comprising a drive unit having two internal combustion engines for the milling roller.

A general problem of construction machines is the limited space available for accommodating all the machine components. The construction machine should have as compact a design as possible in order to be able to keep a sufficiently wide lane open for moving traffic, to be able to be used even in confined spaces and to allow the construction machine to be transported without special permits.

A particular problem of construction machines comprising internal combustion engines is the ever stricter exhaust emission regulations. New exhaust emission regulations make it compulsory for exhaust gases to be treated further by means of additional technology. One known technique for post-treatment of exhaust gases is selective catalytic reduction (SCR). When using construction machines in different countries, the problem still arises of having to comply with various emissions guidelines. The engine technology and exhaust gas treatment technology required to comply with stricter emissions guidelines place high demands on fuel quality, for example low sulphur content, but this cannot be guaranteed in all countries. If fuel of sufficient quality is not available in individual countries, a construction machine having an exhaust gas treatment system cannot be used. It is therefore necessary to produce various designs of construction machines for different countries, the engine technology and exhaust gas technology of which machines are adapted to the respective general conditions. However, producing different configurations increases production complexity, the overall result of which is higher production costs, in particular in the case of small-batch production.

Exhaust gas treatment systems require additives, in particular a urea solution which has to be provided in an additional operating material tank. In one configuration of the construction machine having an exhaust gas treatment system, it is necessary to provide a urea solution, although this is not the case in a configuration without an exhaust gas treatment system. Equipping the construction machine with an exhaust gas treatment system means that changes have to be made to the chassis of the construction machine in order to attach the operating material tank. Otherwise, accommodating an additional tank increases the dimensions of the construction machine.

A sealed double-chamber tank for a motor vehicle is known from DE 10 2011 100 476 A1. The double-chamber tank has a single tank shell which is divided into two chambers. One chamber may hold diesel fuel and the other chamber may hold urea. DE 10 2011 100 476 A1 only describes the double-chamber tank in detail, and not the motor vehicle in which the double-chamber tank is installed. When the double-chamber tank is installed in the motor vehicle, the tank forms a separate component which is supported by the vehicle frame. DE 10 2009 000 094 A1 proposes integrating a tank for receiving a reducing agent in a fuel tank or washing water tank of a motor vehicle; however DE 10 2009 000 094 A1 also does not describe the motor vehicle comprising the fuel tank and the washing water tank in detail.

SUMMARY OF THE INVENTION

An object of the invention is to solve the problem of cost-effective production of self-propelled construction machines in different machine configurations for the respective countries while taking into account the limited space available. The object of the invention is in particular to provide additional operating materials in self-propelled construction machines with the limited space available without the need for major changes to the construction machine.

In one embodiment of a construction machine, in particular a road milling machine, recycler, stabiliser or roller, the additive, in particular the urea solution for operating the exhaust gas treatment system, is provided in an operating material tank integrated in the fuel tank. An alternative embodiment provides the integration of the fuel tank in a water tank of the construction machine, which the known construction machines generally have. When integrating the operating material tank in the fuel tank, however, the construction machine does not need to have a water tank.

Furthermore, the construction machine may be distinguished in that at least the fuel tank is formed from parts of the machine frame when the operating material tank is integrated in the fuel tank; however, when the operating material tank is integrated in the water tank, at least the water tank is formed from parts of the machine frame.

The integration of the operating material tank in a tank formed from the machine frame is advantageous since the structural complexity and the complexity of assembling various machine configurations can be kept as low as possible, and it is possible to standardise the parts used and to thus optimise the manufacturing costs. Furthermore, the complexity of subsequently upgrading or retrofitting the machine is reduced, since additional components can be integrated in the machine frame without further adaptations. The integration of the operating material tank in the fuel tank or water tank does not necessitate any changes to the machine frame, and therefore different production lines for construction machines having or not having exhaust gas treatment systems are not necessary.

Integrating the operating material tank in the fuel tank or water tank allows a standard machine frame to be used for the different machine configurations without major upgrading work. The decision regarding the machine configuration does not have to be taken until the final assembly stage, the operating material tank being built into the fuel tank or water tank in one case or the fuel tank or water tank being used without the operating material tank in the other case. Since the fuel tank or water tank is formed from parts of the machine frame, additional attachments are not required for each instance of equipping the machine.

When the operating material tank is integrated in the fuel tank or water tank, the dimensions of the construction machine can also remain unchanged, since the operating material tank does not take up any extra space on the machine frame. It has been found that the filling volume of the fuel tank or water tank is indeed reduced by arranging the operating material tank in the fuel tank or water tank. However, since the required amount of additive is relatively low by comparison with the amount of fuel or water, the dimensions of the fuel tank or water tank can remain unchanged in practice. Therefore, the structural modifications to the construction machine in order to retrofit an exhaust gas treatment system are minor. The operating material tank preferably has a filling volume that is at most 20%, in particular from 5 to 15%, of the filling volume of the fuel tank, when the operating material tank is integrated in the fuel tank. When the operating material tank is integrated in the water tank, the filling volume of the operating material tank is up to 20%, preferably from 2 to 7%, of the water tank.

The fuel tank has a filling volume that is generally between 200 and 1500 l. If the construction machine is a heavy milling machine, the filling volume of the fuel tank is between 1000 and 1500 l, whereas the filling volume is between 200 and 1000 l if the construction machine is a small milling machine. In the case of stabilisers, the filling volume of the fuel tank is between 800 and 1500 l, for example. The filling volume of the water tank is, depending on the machine type and the machine size, generally between 300 and 5000 l. Milling machines have a larger water tank, and heavy milling machines have a water tank having a filling volume of between 1500 and 5000 l, for example. In the case of small milling machines, the filling volume is between 500 and 1500 l, whereas stabilisers have a smaller (up to 500 l) water tank, or do not have a water tank.

In road milling machines, for example, the fuel tank is generally arranged in the central region of the machine frame. Owing to the static load in this region, the fuel tank is an integral component of the machine frame, for which reason replacement of the fuel tank is not possible. In the fuel tank, the operating material tank can be installed in a simple manner without major upgrading work, so that different machine configurations can be mounted without additional complexity during manufacturing.

A preferred embodiment of the invention provides for the operating material tank to be formed as an exchangeable unit which is designed such that the tank can be inserted into an opening in the fuel tank or water tank, the opening in the fuel tank or water tank being closed by the operating material tank. If the intention is to not equip the construction machine with an exhaust gas treatment system, the opening in the fuel tank or water tank simply has to be closed by a cover. In a construction machine having or not having an exhaust gas treatment system, the opening in the fuel tank or water tank for inserting the operating material tank can also be used for access for finishing, maintenance or servicing operations.

In a particularly preferred embodiment, the operating material tank has a trough part and a cover part, the cover part extending laterally beyond the trough part. If the operating material tank in inserted into the opening in the fuel tank or water tank, the operating material tank having the cover part, which extends laterally beyond the trough part, rests on the fuel tank or water tank, it being possible for the cover part of the operating material tank to be sealed with respect to the fuel tank or water tank in a simple manner.

The operating material tank has a closable tank opening which is preferably arranged on the cover part so as to be able to fill up the operating material tank from the side on which the tank is easily accessible.

The cover part of the operating material tank preferably has a peripheral rim to create a collection trough for additive that overflows during refilling. This prevents urea solution from entering the fuel tank or water tank and/or reaching components of the construction machine that are at risk of corrosion. In order to drain the urea solution, the cover part has an outflow opening having an outflow conduit, by means of which the solution can be guided to the ground without coming into contact with parts of the construction machine. For example, the outflow conduit can lead into or next to the milling roller housing.

The operating material tank can include different materials. Preferably, the operating material tank is a metal tank, in particular an aluminium tank, the inside of which is provided with an anti-corrosion coating, in particular a polyethylene coating.

The operating material tank can have a separate operating material removal unit for each internal combustion engine of the drive unit, which removal unit is preferably inserted into an operating material removal opening in the tank, so that the removal unit can be mounted and demounted in a simple manner. The simple mounting and demounting of the removal unit as a separate component in particular simplifies the equipping or retrofitting of an existing construction machine with the exhaust gas treatment system and the associated operating material tank. In addition to a suction conduit extending towards a low point of the operating material tank, the operating material removal unit can also contain additional components, such as a heating system, a temperature measurement device, sensors, or one or more filters.

In the known construction machines, in which the machine frame is carried by front and rear running gears, the fuel tank having the operating material tank is preferably arranged on the machine frame between the front and rear running gears. A preferred embodiment provides for the arrangement of the fuel and operating material tank between the front and rear running gears, the fuel tank preferably being located below the control platform. This is advantageous in that the operating material tank can be easily accessed from the control platform.

A further particularly preferred embodiment provides that the fuel and operating material tank is covered by at least one tread plate which is arranged above the fuel tank. The tread plate has a preferably closable access opening which is arranged above the tank opening in the operating material tank. A further advantage of the tread plates is the vibration isolation of the machine operator's platform from the machine frame.

In a self-propelled road milling machine, in order to make optimum use of the available space and/or for reasons of optimum weight distribution, the drive unit for the working unit is arranged on the machine frame preferably behind the fuel tank with reference to the working direction of the construction machine and the water tank is preferably arranged in front of the fuel tank with reference to the working direction of the construction machine. In a self-propelled stabiliser, in order to make optimum use of the available space and/or for reasons of optimum weight distribution, the drive unit for the working unit is arranged on the machine frame preferably in front of the fuel tank with reference to the working direction of the construction machine, the fuel tank preferably being arranged in the rear region of the machine frame. The water tank is arranged on the machine frame preferably in front of the working unit with reference to the working direction of the construction machine.

DETAILED DESCRIPTION

As an example of a construction machine,FIG. 1shows a front-loader road milling machine which has a machine frame1, to which front and rear running gears3,4, in particular crawler track running gears, are attached via lifting columns2, so that the machine frame1is adjustable in height relative to the ground5. The running gears3,4may also be wheels. The control platform6is arranged between the front and back part1A,1B, with reference to the working direction A, of the machine frame1. A working unit7is located on the machine frame1below the control platform6and comprises a milling roller9arranged in a milling roller housing8. The milled material is conveyed away by a conveying device10, which is only shown in part inFIG. 1.

A water tank11for holding water for cooling the milling tools of the milling roller9is arranged on the front part1A of the machine frame1in front of the control platform6, while a drive unit12for driving the milling roller9is arranged on the back part1B of the machine frame1behind the control platform6. The drive unit12comprises at least one internal combustion engine (not shown), in particular a diesel engine, having an exhaust gas treatment system (not shown inFIG. 1). The fuel, in particular diesel fuel, is provided in a fuel tank13(FIGS. 2 and 3) which can have a filling volume of from approximately 1000 to 1500 l. The diesel tank is arranged on the machine frame1below the control platform6and above the working unit7between the front and back part1A,1B, with reference to the working direction, of the machine frame1. The water tank11may have a filling volume that is up to 5000 l.

FIG. 2is a simplified schematic view of a section through the part of the machine frame1below the control platform6. The fuel tank13has a bottom part14, side parts15and a cover part16, the parts of the fuel tank being formed from parts of the machine frame1. The fuel tank13is thus an integral component of the machine frame1of the construction machine. The fuel tank13can be filled with fuel via a lateral tank connection piece (not shown).

The cover part16of the fuel tank13has an access opening17which has a substantially rectangular shape of sufficient size to allow finishing, maintenance or servicing operations to be carried out on the inside of the fuel tank. Such access openings are known in the prior art and are referred to as manholes and the closure thereof as manhole covers, because, depending on requirements, they are dimensioned such as to allow a person to climb into the tank. If the dimensions are smaller, they are referred to as handholes and handhole covers. In a road milling machine that has a drive unit12having an internal combustion engine without an exhaust gas treatment system, the access opening17is tightly sealed by a cover18which is screwed to the cover part16of the fuel tank13with a seal19being placed therebetween (FIG. 2).

FIG. 3shows the construction machine equipped with an operating material tank20for holding an additive. The operating material tank20is filled with a urea solution which is provided for operating an exhaust gas treatment system21(only shown indicatively). Said tank forms a modular unit which is inserted with an exact fit into the fuel tank13when the cover18(FIG. 2) is removed. The operating material tank20is a metal tank, in particular an aluminium tank, the inside of which is coated with a polyethylene coating22to protect against corrosion. The filling volume of the operating material tank20is for example from 5 to 20%, in particular up to 15%, for example approximately 10%, of the filling volume of the fuel tank13.

The operating material tank20has a trough part23having a bottom part24which includes two bottom plates25,26extending obliquely with respect to one another, so that the tank20has a low point27. The trough part23is sealed by a cover part28which extends outwards beyond the side parts29of the trough part23, so that the cover part28of the operating material tank20rests on the cover part16of the fuel tank13. The cover part28of the operating material tank20is screwed to the cover part16of the fuel tank13with a seal30being placed therebetween, so that the fuel tank is tightly sealed. The operating material tank20has a tank opening32which is sealed by a tank cover31and is provided on the cover part28. The cover part28of the operating material tank20has a peripheral rim33, so that the cover part is formed as a collection trough in order to collect operating material that overflows during refuelling. An outflow opening34having an outflow conduit35leading towards the ground is provided on the cover part28and can terminate in the milling roller housing8, which is open downwards.

To remove the additive, an operating material removal unit36is provided which is inserted into an operating material removal opening37in the cover part28of the operating material tank20. The operating material removal unit36has a suction conduit38which extends as far as the low point27of the tank20. A conduit39is connected to the removal unit36and leads to a suction pump40. An operating material conduit41leads from the suction pump40to the exhaust gas treatment system21of the internal combustion engine (not shown) of the drive unit12. To supply a second internal combustion engine of the drive unit12, a second removal unit can also be provided in addition to the first operating material removal unit36.

Tread plates42are arranged on the control platform6above the fuel and operating material tank13,20at a distance from the cover parts16,28. An access opening43, which is sealed by a pivotable cap44, is located above the tank opening32in the operating material tank20in one of the tread plates42.

FIGS. 2 and 3show that equipping the construction machine with an additional operating material tank20does not necessitate any major structural modifications, the dimensions of the machine not being increased either.

As another example of a construction machine,FIGS. 4 and 5are side and plan views, respectively, of a stabiliser equipped with a fuel and operating material tank13,20, the operating material tank20being formed in the same way as the tank of the embodiment inFIGS. 1 to 3. The corresponding parts are provided with the same reference numerals. The stabiliser has front and rear running gears3and4which are carried by a machine frame1. The control platform6is located in front of the front running gear3with reference to the working direction, the working unit7and the drive unit12being arranged behind the control platform6and between the running gears2,3. The fuel tank13is located in the rear region of the machine frame1, the tank again being formed from parts of the machine frame1. The operating material tank20is inserted into an access opening17(shown by dashed lines) in the cover part16of the fuel tank13and rests together with the cover part28on the cover part16of the fuel tank13, so that the access opening17is tightly sealed.

FIG. 6shows the back part of the machine frame1, an operating material tank not being installed in the fuel tank13. For this machine configuration, the access opening17of the fuel tank13is tightly sealed by a cover18, structural modifications to the machine frame not being necessary.

An alternative embodiment is shown inFIG. 7, in which the operating material tank is not integrated in the fuel tank but in the water tank. The corresponding parts are provided with the same reference numerals. The parts of the water tank11are formed from parts of the machine frame1in this embodiment too, so that the water tank11is thus also an integral component of the machine frame1. In this embodiment, however, the fuel tank13does not have to be formed from parts of the machine frame1.FIG. 7is a section through the parts of the machine frame1that form the water tank1. Like the fuel tank13, the water tank11comprises a bottom part11A, side parts11B and a cover part11C. There is an opening11D in the cover part11C, into which the operating material tank20is inserted. The operating material tank20inserted into the water tank11is, in the present embodiment, identical in construction to the operating material tank that is inserted into the fuel tank13(FIG. 3).