DE10300745A1 - Drive system for a working machine especially an asphalt laying road machine has a branched power drive with at least two commonly connected outputs - Google Patents

Abstract

A drive system for a working machine, especially for road constructing machines, comprises a branched power drive having at least two of the machine drives connected to a common drive branch. An Independent claim is also included for a process using the above drive system.

Description

The invention relates to a drive system for work machines, especially for Paver.

Asphalt pavers are mobile machines, which are mainly used for the installation of asphalt mixes in road construction become. When working, the paver pushes you with asphalt loaded truck or another delivery vehicle. The so-called bunker walls are folded down to the handover the material from the truck or the delivery vehicle to the paver to enable. The truck or the delivery vehicle tips the material into the bunker of the paver. From there, the material is transported on a conveyor belt, the so-called Scratch tape, conveyed by the machine and falls on the back wall of the paver out. At this point, the mix of snails is distributed across. The following one, from the paver drawn screed (implement) floats on the material and pulls it smooth, and thus creates the surface profile.

The screed usually has several compaction units, such as. Tamper bars, vibrators, Vibrators or pressure bars for pre-compression. The final compression is subsequently through road rolling causes. The installation height is through change the setting angle at which the screed runs in the direction of travel. This is the height the articulation points of the screed's pull arms via so-called leveling cylinders changed.

Asphalt pavers usually point following individual drives, which are integrated in a drive system are, on: Rotary drives for the chassis, rotary Drives for the scratch tapes, rotary drives for the screws, linear drives for the bunker wall cylinder, linear Drives for the Leveling cylinders, linear drives for lifting and lowering the Screed, linear drives for the telescopic screed and rotary drives or a rotary one Drive system for the screed compacting devices, which are usually mechanical crank or eccentric gear or unbalance exciters work linearly using rotary or pulse hydraulic.

Purely mechanical drive systems, purely hydrostatic drive systems and diesel-electric drive systems are out for pavers EP 0 489 969 A1 known.

Drives in the purely hydrostatic drive system usually an internal combustion engine via a pump transfer case all hydraulic pumps on. These hydraulic pumps are different Hydraulic motors fed, which feed the individual drives.

For the travel drives are known to use earth reduction gears. Frequently are such gears for scraper belts and snails used as this may be less expensive is as the extra cost for the otherwise required hydraulic slow-speed motors.

The machine performance is largely in the rotary drives of the undercarriage, the scraper belts and the snails implemented.

It is also known that the scraper belts and screws can also be operated with separate supply pumps. Furthermore, a paver points various (constant) pumps, some of which are used as feed pumps and partly as supply pumps for the remaining Aggregates, e.g. Compression drives, lifting and other hydraulics function.

It is also known to be a generator for the to use electric screed heating. Heating parts the screed is necessary in order to cool down too quickly and to "stick" the installed To prevent material.

A good regulation of the driving speed of a paver is essential from an application technology perspective. The actual speed of the travel drives is usually on gears Earth reduction gears detected and closed with the help of proximity sensors a control and regulating device returned, that via adjusting elements the hydraulics regulate the speed. The actual speed value acquisition is a frequency count from a measurement point of view. The proximity sensors provide impulses that over a fixed time interval is counted become. The number of pulses is then proportional to the output speed. With ever lower speeds, the number of pulses drops, so that at some point regulation is no longer possible is. Because of this, the working speed is down limited. For pavers a lowest working speed of 1 m / min is known.

In very few individual cases a working speed below this limit may be useful. More important for but the drive is that the full effective machine performance can be used in the entire working speed range. pavers can both with wheel chassis as well as be equipped with crawler tracks. Paver with wheeled undercarriage have individually driven rear wheels or about a driven rear axle with differential gear. they are equipped with one or two front axles or two or four individually suspended front wheels. Often they are Front wheels / axles additionally driven to improve traction. In addition to one very good controllable and adjustable stepless translation of hydrostatic However, gearboxes of this type also have their typical disadvantages on.

This is particularly the poor efficiency, which is 50% to 80% depending on the operating state. Even when the machine is only ready for operation, the machines consume considerable amounts of energy for the towing capacity of the hydraulic drives. In addition, there is high noise emissions and possible oil leakage from a hydrostatic drive bes disadvantageous. The high noise emission is also increased by the cooling air flow required for engine and oil cooling.

In addition to a high environmental impact the required cooler creates a high space requirement in the paver with purely hydrostatic drive. Furthermore, a necessary one Sound insulation often can only be implemented poorly because there is no installation space available. Furthermore, the internal combustion engine must be dimensioned relatively large, because he also the high hydraulic losses in the form of mechanical energy must provide. That means the engine is designed larger must be considered from the point of view of the application's performance requirement should be dimensioned which in turn is unnecessary Energy losses, noise emissions, larger engine coolers and associated space consumption. Still disadvantageous on the hydraulic system are the high operating costs due to the high Fuel consumption.

With purely mechanical drive systems for pavers it is particularly disadvantageous that a stepless regulation is very difficult to implement. Linear drives can also only be used very difficult to realize. Other disadvantages are complex overload protection, a relatively inconvenient Power-to-weight ratio, high space requirements, unfavorable energy transfer on the implement and a low power density.

Diesel-electric drive systems for pavers have good efficiency only in a very limited Workspace. Other disadvantages are a high power to weight ratio, practical not feasible linear drives, a high electrical and electronic Manufacturing effort, a high susceptibility to failure and an associated cost disadvantage.

It is therefore the task of the present Invention, a drive system and a method for driving work machines, especially pavers, indicate which one is higher Makes the paver's efficiency possible and eliminates the aforementioned disadvantages of the known drive systems. This is supposed to lower fuel consumption with the same performance become realizable. Furthermore, with the drive system according to the invention lower noise emissions accompanied.

According to the invention, this object is achieved by the features in the characterizing part of claim 1 (device claim) and the features in the characterizing part of claim 16 (process claim) in cooperation with the features in the generic term. Appropriate configurations the invention are contained in the subclaims.

A particular advantage of the drive system according to the invention is that the main part of the performance for a work machine, in particular a paver, over one Gear branch with high efficiency, e.g. a mechanical transmission branch and only one if possible small part of the performance over a stepless, e.g. transmit a hydrostatic transmission branch and this increases the overall efficiency of the drive system.

For this purpose, a drive system according to the invention for one Working machine, in particular a paver, a power split Gearbox, with at least two drives of the paver with one common gear branch are connected. Preferably the common one The main transmission of the power-split transmission.

At least one travel drive is in accordance with the invention and at least one drive for a conveyor belt connected to a common drive shaft.

Furthermore, the power split Gearbox on at least one summing gear, the main gear and interconnects the at least one auxiliary gear via a summing gear are.

The main gear can be a mechanical gear or be an electric transmission.

The at least one auxiliary gear can be a hydrostatic transmission or an electric transmission or a hydrodynamic gear or a pneumatic gear or be a mechanical transmission.

In a preferred embodiment the drive system can be a drive shaft and / or a drive chain exhibit. The drive shaft can be a cardan shaft.

Furthermore, the drive system in a preferred embodiment Drives for at least one undercarriage and / or at least one conveyor belt and / or at least one distribution screw and / or at least one Bunker wall cylinder and / or at least one leveling cylinder and / or at least one lifting cylinder and / or at least one screed telescopic cylinder and / or have at least one compression device. The conveyor belt can be a scratch tape.

The drive system can be a primary drive Have internal combustion engine. This internal combustion engine is preferred a diesel engine.

Furthermore, one is preferred variant a central transfer case is provided, which modified Pump transfer case with a mechanical output and at least one Downforce for can be a hydrostatic pump.

In the method according to the invention for driving pavers, several outputs use a common transmission branch of a power-split transmission as the main transmission. A common drive shaft preferably supplies at least one drive for a conveyor belt and at least one travel drive. This means that the main part of the power can be provided, for example, via a mechanical transmission branch are transmitted with high efficiency, the smallest possible part being transmitted via a continuously variable transmission branch with lower efficiency.

The main gearbox and auxiliary gearbox are about Summing gear interconnected.

Are in the paver's operation the input speeds of the summation gear designed so that the main transmission side input shaft forms the total power shaft. The hydrostatic auxiliary gear can be supplied via constant pumps become.

In the paver's transport aisle the input speeds of the summation gear designed so that the main transmission side input shaft and the secondary transmission side Form input shaft partial power waves. The conveyor belts and Can snails be shut down mechanically.

The invention is hereinafter in an embodiment explained in more detail with reference to drawings. It demonstrate:

1 : a schematic representation of a drive system according to the invention,

2 : A schematic representation of the transmission of a drive system according to the invention.

1 shows schematically an inventive drive system for a paver. For the main drives, the travel drives 18 who have favourited Conveyor Belts 38 and the snails 34 a common mechanical drive is provided. This drive is via a cardan shaft 14 and a central transfer case 30 with a diesel engine 10 connected, which serves as the primary drive. The central transfer case 30 can be, for example, a modified pump distributor gear, which in addition to drives for hydrostatic pumps 12 has a mechanical drive. The mechanical transmission can be done by means of a drive shaft 24 and / or drive chain 36 or can be realized in another way.

The common drive shaft 24 is in each case with the drive wheels of travel drive 18 , the snails 34 and the conveyor belts 38 via summation gear 20 (Three-shaft gear) connected, the summing gear on the respective second input shaft 20 a hydraulic motor 16 sitting. The summation gear 20 are summation gearboxes of several hydrostatic-mechanical power split gearboxes with a common mechanical supply.

The snails 34 and other drives can be connected in a similar way. However, since the worm drives are not connected to the drive shaft 24 in line with another transfer case, a second transmission, which acts as a drive chain 36 is designed to be provided to the snails. The number of drives can be increased or decreased as required.

According to the invention, the advantages of hydrostatics combined with the good efficiency of a mechanical transmission. For this purpose, a drive system for road pavers includes a power split Gearbox, with at least two drives of the paver with one common gear branch are connected, which is preferably the main gear is.

The basic idea is that the main part of the power is transmitted via a transmission branch with the highest possible efficiency, for example via a mechanical transmission branch, and only the smallest possible part of the power is transmitted via a stepless, eg hydrostatic transmission branch. The two sub-transmissions are in a summing gear before final drive 20 merged.

It can generally be found in main gearboxes and Differentiate auxiliary gear. Of course, the continuously variable transmission does not have to necessarily be hydrostatic. Neither does the main transmission branch be mechanical. According to the invention, the fact that that apart from wheel manufacturers with differential gear the main drives of pavers lie almost aligned on one axis. The main drives are the two rear travel drives and the drive or drives the conveyor belts, the so-called scratch tapes.

Furthermore, the fact according to the invention considered, that the drive speed of all main drives, i.e. the conveyor belts and the travel drives, similar are low and in absolute terms, a very limited range exhibit.

2 shows a schematic representation of the transmission of a drive system according to the invention for a road paver. The main gearbox can 28 in front of or behind the inner distribution gear 30 are located. The distribution gear 30 may have additional transducers. The converter, the distribution gear 30 and the main transmission 28 are housed in a common gear housing and form the central transfer case 26 out. For the design of the common drive branch, it is obvious that the speed of the common drive shaft 24 to the speed required in main operation or in the main operating point of the largest power consumer, so that at this working point there is no power via the continuously variable auxiliary transmission 32 is transmitted. This means that the respective continuously variable auxiliary transmission 32 for this operating point on the speed 0 Is set to (zero). All summation gears 20 can have such a basic gear ratio that the typical or most frequently selected working speed is reached when the continuously variable partial transmission is at a standstill. The highest possible efficiency, which is achieved with the drive system according to the invention, is particularly advantageous. Furthermore, a lower cooling capacity is necessary with a hydrostatic drive in the stepless branch. Since the hydrostatic power share has been reduced, there is also less noise emission. Furthermore, are poorer and thus cheaper hydraulic components can be used for a system according to the invention compared to the prior art.

It is also advantageous to increase the lower speed of the mechanical drive branch. This is particularly desirable because, at higher speeds, lower torques and therefore lower strength requirements are required of the mechanical components. This is possible insofar as the speed of the common drive train is determined via a constructively useful, but relatively high value, so that there is an input speed 0 (Zero) of the respective continuously variable transmission branch on the drive of the summing transmission 20 would set a speed above the highest working speed. The desired working speed must then be set via the respective stepless branch so that it counteracts the common supply, i.e. always delivers reactive power. The main gearbox input shaft of the summation gear 20 then the total power wave is always in the machine's working cycle. The stepless branch reduces the speed on the main transmission side.

This solution, which is not optimal in terms of energy, offers considerable design advantages. The speed in the main transmission 28 can be chosen higher. Therefore, the elements of the main transmission branch can be dimensioned smaller with the same performance of the machine. The drive must also be in the power take-offs 32 not necessarily continuously by speed 0 (Zero) adjustable. That is why you can use variable pumps or other adjusting elements in the power take-offs 32 can be dispensed with, since adjustment, for example, can only be carried out on the output side, for example via adjustable hydraulic motors. The hydrostatic auxiliary gear 32 can therefore be supplied via constant pumps. This enables the number of hydraulic pumps to be reduced, since several pumps can be replaced by one pump with power division. The central transfer case can also be dimensioned to be correspondingly more compact due to the smaller number of output shafts. A typical drive for a road paver according to the state of the art has two variable pumps for the travel drive in the middle to upper performance class 18 and one variable pump for conveyor belts 38 and snails 34 , As a rule, the travel drives include adjustment motors. According to the embodiment of the invention, the six adjusting members could be reduced to four adjusting members, combined with a saving of up to three output shafts of the central transfer case for pumps. In addition, there would be the output for the main gear 28 , so that a saving of two hydraulic adjustment elements and two outputs of the central transfer case would remain compared to the prior art.

If a higher speed of the travel drives is required in the transport aisle in contrast to the work step, this required higher working speed for the travel drives can be achieved by reversing the direction of rotation of the motors (via a switching valve) in the auxiliary transmission 32 be generated. Then the drive shaft 24 to the total power shaft and main and secondary gear 28 . 32 become partial power waves. The conveyor belts 38 and snails 34 can be either hydrostatic or mechanical (by braking) on the speed 0 (Zero) can be set. In the case of mechanical adjustment, the motors become pumps, the flow of which can be switched to that of the hydrostatic supply (by means of switching valves), so that a further increase in the speed of the travel drives is possible.

In addition to a mechanical-hydrostatic structure of a branched circuit according to the invention Drive system come for the main and auxiliary gears basically other gear types into consideration.

The construction of a mechanical-electrical, power-split transmission with a mechanical main transmission and electrical auxiliary transmissions is particularly expedient, the travel drives and the drives for the conveyor belts 38 use a common transmission branch as the main transmission, and via a common drive shaft 24 be supplied. Compared to the variant according to 1 are the hydrostatic pumps 12 to be mentally replaced by generators; from hydraulic motors 16 become electric motors. The advantage over a diesel-electric non-power-split transmission according to the prior art is that the electrical components can be designed for relatively low power. This increases the overall efficiency of the drive system. In part-load and engine braking mode, excess electrical energy can be used, for example, to heat the screed or for other electrical consumers. This means that the generator, which is actually only responsible for heating the screed, can be saved.

Furthermore, the structure of a power split gearbox according to the invention for a paver also done electrically. It lends itself to the main transmission therefore to be interpreted electrically since the electric motor is on an almost fixed Speed can be designed. This is cheap because Electric motors, especially three-phase motors, their optimal efficiency have only in a very narrowly limited speed range. Also in this variant can in the partial load range of the generator or when the engine is braking in the main gearbox or in the braking mode of engines in auxiliary gearboxes electrical power reserves for heating the screed or for others electrical consumers are provided.

The invention is not restricted to the exemplary embodiment shown here. Rather it is possible to implement further design variants by combining and modifying the means and features mentioned, without leaving the scope of the invention.

10

diesel engine

12

hydrostatic pump

14

propeller shaft

16

hydraulic motor

18

traction drive

20

summing

22

Bohle (Working unit)

24

common drive shaft

26

central Transfer Case

28

main gearbox

30

distribution gear

32

hydrostatic In addition to transmission

34

slug (Working unit)

36

drive chain

38

conveyor belt (Scratches band)

Claims (22)

Drive system for working machines, in particular for road pavers, characterized in that the drive system has a power-split transmission, at least two outputs of the paver being connected to a common transmission branch. Drive system according to claim 1, characterized in that the common transmission branch is a main transmission ( 28 ) is. Drive system according to claim 1 or 2, characterized in that at least one travel drive ( 18 ) and at least one drive for a conveyor belt ( 38 ) with a common drive shaft ( 24 ) are connected. Drive system according to claims 1 to 3, characterized in that the power-split transmission has at least one three-shaft transmission, the main transmission ( 28 ) and the at least one auxiliary gear ( 32 ) are connected via a three-shaft gearbox. Drive system according to claim 4, characterized in that the three-shaft gear is a summing gear ( 20 ) is. Drive system according to claim 1 to 5, characterized in that the main transmission ( 28 ) is a mechanical transmission or an electrical transmission. Drive system according to claim 1 to 6, characterized in that the at least one auxiliary gear ( 32 ) is a hydrostatic transmission or an electrical transmission or a hydrodynamic transmission or a pneumatic transmission or a mechanical transmission. Drive system according to claim 1 to 7, characterized in that the drive system at least one drive shaft and / or a drive chain ( 36 ) having. Drive system according to claim 8, characterized in that the drive shaft is a cardan shaft ( 14 ) is. Drive system according to claims 1 to 9, characterized in that the drive system drives for at least one undercarriage and / or at least one conveyor belt ( 38 ) and / or at least one distribution screw ( 34 ) and / or at least one bunker wall cylinder and / or at least one leveling cylinder and / or at least one screed lifting cylinder and / or at least one screed telescopic cylinder and / or compression devices. Drive system according to claim 3 or 10, characterized in that the conveyor belt ( 38 ) is a scratch tape. Drive system according to claims 1 to 11, characterized in that that the drive system is an internal combustion engine as the primary drive having. Drive system according to claim 12, characterized in that the internal combustion engine is a diesel engine ( 10 ) is. Drive system according to claims 1 to 13, characterized in that the drive system is a central transfer case ( 26 ) having. Drive system according to claim 14, characterized in that the central transfer case ( 26 ) is a modified pump transfer case, which has a mechanical output and at least one output for a hydrostatic pump ( 12 ) having. Process for driving work machines, in particular for driving road pavers with several drives, characterized in that several drives a common transmission branch of a power-split transmission use as main gear. A method according to claim 16, characterized in that a common drive shaft has at least one drive for a conveyor belt and supplies at least one travel drive. A method according to claim 16 or 17, characterized in that that main gear and auxiliary gear via summation gear with each other are connected. A method according to claim 18, characterized in that the input speeds of the summation gear are designed so that the main transmission side input shaft in the paver's operation forms the total power wave. A method according to claim 18, characterized in that the hydrostatic auxiliary gear is supplied by constant pumps become. A method according to claim 18, characterized in that the input speeds of the summation gear are designed so that the main transmission side input shaft and the secondary transmission side Input shaft in the paver's transport aisle form. A method according to claim 21, characterized in that conveyor belts and The screws are stopped mechanically.