DD293949A5 - METHOD AND DEVICE FOR MEASURING AND INDICATING EXPOSURE IN TRANSACTIONS FROM AGRICULTURAL DEVICES - Google Patents

Abstract

The invention relates to a method and a device for monitoring the drive train of an agricultural machine in terms of overload and utilization. Each time the slip occurs for the first time, the number of slip revolutions is added during a measurement time cycle. If the calculated number exceeds the permissible number of slip revolutions, a signal is generated which identifies the state overload. A new meassage cycle begins with the triggering of the signal to take into account the effects resulting from a changed behavior of the tractor driver. Taking into account the speed difference between the input speed and the output speed of the relative rotation permitting clutch, the quality of the signal is changed. In addition, the utilization rate is displayed from the ratio of the actual measured to the maximum number of slip revolutions. This procedure ensures that the driver is warned of a blockage or congestion, which could result, for example, in the overheating or destruction of the coupling protecting the device or of a part in the vicinity of the device. In addition, the extent to which the driver uses the efficiency of the device is indicated. This makes it possible to optimize the operation. {Agricultural machine; Drive train; Overload; slip; Meszzeittakt; Capacity utilization; Slip revolutions; Speed difference; Capacity utilization; Clutch; Blockade; overheating}

Description

Rs = χ -Jini- χ 100%

takes place, in which l _{according to} the number of slip revolutions (l _ge m) f tgem determined in the measuring time clock (t _int ) since the beginning of the time since the beginning of the current measuring time clock (t _int ), t _in the period of the measuring time clock, indicated in the same time unit like the elapsed time (t _gem ) in the current measuring time clock, and l _too! mean the predetermined maximum allowable number of slip revolutions per Meßzeittakt.

3. The method according to claim 1, characterized in that the Meßzeittakt (t _int ) is zwai minutes.

4. The method according to claim 3, characterized in that the permissible number of slip revolutions (I _ZU |) is limited to four revolutions.

5. The method according to claim 1, characterized in that the limit value for the quotient (Q _2Ul ), _below which a change in the signal is triggered, the value of 0.9.

6. Device for carrying out the method according to claim 1, characterized in that the torque limiting clutch is designed as a friction clutch (5), that an evaluation unit (22) is provided, a member (23) for forming the speed difference, an addition member (24) and a timer (25) and a limit comparator (26) which is connected to a signal transmitter (27) comprises.

7. Device according to claim 6, characterized in that a Quo'.ientenglied (28) for forming the quotient of the of the tachometer (16 .. 17) detected speed (n _{1 (} n ₂ ) of the output and the drive side of Friction clutch (5) and a Quotientengrenzwertvergleicher (29) are provided, which is also connected to the signal generator (27).

8. Device according to claim 6, characterized in that the tachometer (16,17) toothed pulleys (19) with the same numbers of teeth and proximity sensors (18).

9. Device according to claim 8, characterized in that the toothed discs (19) six teeth (21) and six tooth spaces (20).

For this 5 pages drawings

Field of application of the invention

The invention relates to a method and apparatus for triggering a signal indicative of achieved preset load limits in the powertrain of a tractor-driven, self-propelled or stationary agricultural machine having a torque limiting clutch whose input and output speeds are measured and where the speed difference corresponding slip rotation are summed up.

Characteristic of the known state of the art

From EP 0137247A2 a device for protecting a clutch against overheating is known, which is arranged between an engine and a transmission. As a protection against overheating of the coupling, a determination device of the drive torque is provided, which enables a summed calculation of the slip values via the determined rotational speeds and is used for triggering warning signals by comparison with preset slip values. In DE-OS 2910365 a method for triggering a display is described in which each implement of the tractor is assigned a respective overload protection characterizing resistor combination, which determines the desired values of an overload clutch via an electronic circuit arrangement.

From US 4039781 it is known to arrange a clutch between a drive motor and an extruder machine, which makes a recording of the input and output speeds via speed sensor and provides an associated circuit control of the clutch and the output of an acoustic warning signal overload.

Methods and devices for measuring the torque applied to a drive train and for triggering signals when predetermined limit values are exceeded are already known in mechanical engineering. In this case, the change in the torque is used to predict whether an exceeding of the predetermined limit value occurs. The switching process is initiated before reaching the predetermined limit, so that even before reaching the limit due to the signal, the automatic shutdown by disconnecting the clutch takes place (DE 34378087 C 2). Such methods and devices are not suitable for use in connection with agricultural machines. In agricultural machines, it is necessary that short-term overloads are allowed when sit occur, for example, when starting the machine to accelerate the masses to be moved. In addition, the device must be suitable for the rough operation of agricultural equipment.

Object of the invention

The object of the invention is to provide a method and a device for measuring and displaying load conditions in drive trains of agricultural equipment in such a way that a harmful exceeding of predetermined limits is avoided and the device is able to cope with the rough operation of agricultural equipment.

Explanation of the essence of the invention

On this basis, the object of the invention is to propose a method and a device for triggering a signal for the achievement of predefined load limit values, which are adapted to the operation of agricultural machines and allow the operator to intervene but, on the other hand, also make optimum use of the tractor. Enable machine combination.

This object is achieved in that the during a starting from the first occurrence of a slip starting predetermined Meßzeittakte (t _inl ) or in subsequent persistent slip during one of the adjoining

Messzeittakte (t _int ) the calculated slip revolutions (I _011n ) when exceeding the predetermined allowable slip revolutions (Ui) trigger a signal, the release of the signal in each case a new Meßzeittakt (t _int ) starts to run and that at the time of exceeding the allowable number is formed by slip revolutions (Ui) from the measured at that time drive speed (n,) and the output speed (n ₂ ) of the quotient, wherein the input speed, the denominator and the output speed is the counter, and that the triggered signal falls below a predetermined quotient is changed.

By this procedure, it is achieved that the driver on the one hand receives knowledge that a case of congestion has occurred, but that due to the respective new beginning of a Meßzeittaktes after triggering the signal and the meantime due to the signal from the driver changed drive situation is taken into account, each currently a state to be able to show. The driver has z. B. on the change of the driving speed possibility to influence the use of power.

For monitoring the entire system, only slip of the clutch as a function of time is of interest. A reference to the actual speed is not required. Only the absolute slip leads to a heating of the clutch and thus acts performance-limiting. The directly transmitted power passing through the clutch is not of interest in this regard. The set target torque of the clutch to be monitored, however, is significant, since this is directly proportional to the supplied energy and thus heating at the same slip. The coupling and also the permissible limits are determined depending on the application. So you are on the device, which is driven by the tractor, tuned.

Although the drive in the drive train for the protection of overload provided coupling ensures on the one hand for a hedge in a specific overload case, the driver does not know to what extent he the performance limits of the clutch and thus the machine to which the clutch is adapted and which should secure, uses.

A constant exceeding of the load limits of the coupling leads namely to a reduced life of both the clutch and the machine.

In order to determine whether it is only a short permissible excess of the permissible number of slip revolutions or, for example, the risk of blockage, it is provided that at the time of exceeding the permissible number of slip revolutions from the measured at that time output speed and the input speed the quotient is formed. So signals of different quality are generated. In a normal excess, at the output speed Jnd input speed differ only slightly from each other, the driver receives only an indication that he is in the area dt r overload, which he, for example, by reducing the driving speed again

can cancel, for example, is signaled at a greater deviation of the output speed of the input speed that the risk of blockage of the machine and thus the dangerous overload is given. As a result, the driver will immediately stop the drive and possibly also stop to remove the existing blockage of the machine or a stone or the like.

In order to make the driver of a tractor or a self-propelled machine recognizable whether he makes optimum use of the performance limits of a machine, it is provided in a further embodiment of the method that a comparison signal according to the function

R. = -! Si ™, χ Ji = L χ _1O o%

tgm "ml

takes place, in which l _{according to} the number of slip revolutions determined in the measurement time clock since its beginning, t _gam the time since the beginning of the

current Meßzeittaktes, t _in , the duration of the Meßzeittaktes, indicated in the same unit of time as t _o , "" and U is the predetermined maximum allowable number of slip revolutions per Meßzeittakt.

So it shows the relative slip. In such a procedure, a display is effected, which is too strong Utilization of the device during a Meßzeittaktes indicates a value of more than 100% for the relative slip without

the maximum permissible number of slip revolutions has already been reached. This information gives the

Operator an indication to reduce the driving speed, while maintaining this mode of operation the machine

could be overloaded in the course of Meßzeittaktes. Such a procedure allows a different impression of the

To maintain utilization of the device. With appropriate use and implementation in a suitable driving strategy, the Machine utilization improved and thus the working speed can be optimized. It is proposed to set the measuring time clock to a duration of two minutes. It has been found useful for most applications, a number of four permissible slip turns,

although these are chosen differently depending on the task of the clutch and torque adjustment in individual cases

The limit value for the quotient, below which a change in the signal is triggered, should follow the Invention 0.9. This means that when the speed on the abduction side drops off, it is more than 10% higher than on the drive side.

it is believed that this may be a blockage that could result in damage to the device or the coupling provided to secure the device.

According to the invention, it is proposed for carrying out the method that the torque limiting clutch as Friction clutch is formed, that an evaluation unit is provided, which is a member for forming the speed difference, a Addition element and a timer and a threshold comparator, which is connected to a signal generator has. The actual slip occurring during oze Meßzeittaktes are added up by the addition member. The timer serves on the one hand to limit the Meßzeittaktes and on the other hand to determine the elapsed time

within the Meßzeittaktes. In the limit comparator, it is determined whether the allowable number of slip revolutions is exceeded and whether the signal generator is to be caused to generate a warning signal.

In a further embodiment, a quotient member for the formation of the quotient of the detected by the tachometers Speeds of the output and the drive side of the friction clutch and a Quotientengrenzwertvergleicher provided, the

also connected to the signal generator.

When falling below a predetermined quotient the signal of the signal generator is changed, so that therefore an increased Attention of the operator is generated. In a further embodiment, it is further provided that the tachometer toothed pulleys with the same numbers of teeth and Include proximity sensors. The toothed disks preferably have six teeth and six tooth spaces. Such, albeit rough division, is for the

most intended applications of agricultural technology sufficient. Based on the four permissible

Slip revolutions during the Meßzeittaktes of two minutes so there are a number of 24 permissible pulses. If this number of pulses is exceeded, the warning signal is triggered. embodiment A preferred embodiment is explained with reference to the drawing. It shows 1: a tractor-device combination, 2: the Anoidnung and training of the measuring device, 3 shows a circuit diagram, 4: two slip diagrams and Flg. Fig. 5: various diagrams relating to the absolute and relative slip in different load cases. The procedure will be described with reference to the proposed device according to the invention.

In FIG. 1, the tractor provided for driving and pulling the device 2 is designated 1. The tractor 1 has a belt shaft 3, to which a propeller shaft 4 is connected, the other end is connected to an input shaft 13 of the device 2. The propeller shaft 4 is the device downstream connected to the device for triggering the signal. This comprises the friction clutch 5. The friction clutch 5 consists of the housing 6 with the connecting flange 7 for connection to the input shaft 13 of the friction clutch and the hub 8 for connection to the output shaft 14. The hub 8 is provided with a radially extending flange 9, the is designed as a carrier for the friction linings 10. The friction linings 10 rest on the one hand on the radially inner side of the housing 6 and on the other hand on the pressure plate 11. The pressure plate 11 is replaced by springs 12,

which are arranged circumferentially distributed, applied. About the number and design of the friction surfaces and the Reibflächenpaarung and the biasing force of the springs 12 which can be transmitted through the friction clutch 5 moment. The selection and design of the friction clutch 5 is made in adaptation to the respective machine to be driven. The input shaft 13 and the output shaft 14 are tachometers 16,17, which are each held in bearings 15 assigned. The tachometer 16,17 each comprise a toothed disk 19 and a proximity sensor 18. The toothed wheel 19 has six circumferentially spaced teeth 21 and a corresponding number of tooth gaps 20. When rotating at the same speed drive shaft 13 and output shaft 14 (ni = n ₂ ) go through the Toothed disks 19 at equal intervals, the positions of the sensors 16,17. In the event that the output shaft 14 is slower than the Eingangpwelle 13, a slip between the housing β and hub 8 is present. This slip is by the measurement or counting and addition of the pulses, resulting from the selected Meßzeittaktes of two minutes and the pitch of the toothed discs 19, gewilttelt and with the number of permissible slip revolutions of four, the 24 pulses due to the division of the Toothed disks 19 result, as shown in Figure 4, compared. The upper graph shows, for example, the behavior of the friction clutch 5 during a measurement time of 2 minutes, in which the pulses are added up. It can be seen that the limit value for the slip revolutions thereof in the measuring time clock 24 is pulses which is calculated from the permissible number of slip revolutions of 4 multiplied by the number of teeth 21 of the toothed disks 19 (4x6 = 24).

From Figure 3, the circuit structure can be seen. In the field of view of the tractor driver on the tractor 1, the signal generator 27 and the load indicator 30 are arranged. These are connected to the measuring device via lines. The slip pulses measured by the tachometers 16, 17 are fed to an evaluation unit 22, which comprises an addition element 24 and a differential element 23. In the differential element 23 is determined whether speed differences between the input speed n, and the output speed n _{2 are} given. For this purpose, the pulses, as already explained in connection with FIG. 4, top illustration, are used. In the adder 24, the resulting slip revolutions or parts of slip revolutions (pulses) are added during the Meßzeittaktes. The threshold comparator 26 judges whether the accumulated number of slip revolutions l _g , _m in relation to the allowable number of slip revolutions l, _u , in the measurement timing t | _{nl be} exceeded. If this is the case, the limit value comparator 26 triggers a signal of the signal generator 27.

In order not only to be able to determine that an exceeding of the predetermined limit value for the slip revolutions is given liui, but also to obtain an indication of the quality of the signal, a quotient member 28 is additionally provided to which the measurement results of the tachometer 16,17 are supplied and in which the measured speeds of the drive n, and output n _{2 are put} into proportion, according to the formula

Q --Ui

Πι

From this it can be determined how far the output speed n ₂ differs from the input speed n ₍ with only slight deviation, a different quality is required for the warning signal than, for example, with larger speed differences.) In the case of only a smaller deviation of the output speed n ₂ from the drive speed n < the effect on the function of the device and the securing friction clutch 5 is less than a greater deviation of the speed, which can signal, for example, the blockade of a device.For this reason, a quotient Q _w i is specified as a limit, below which the quality of the generated signal at the same time exceeds the maximum allowable number of slip revolutions l _lul, an increased attention erforderndes signal is triggered. in Quotientongrenzwertvergleicher 29 is determined whether through n from the output speed ₂ and the input speed n _t calculated Quotie the permissible quotient Q, _U | is fallen short of. The quotient limit comparator 29 generates an additional signal for the signal generator 27 in the case of falling below. It has been determined that, when the output rpm n _{2 is} undershot in relation to the drive dodge number n, then 10%, ie at a Q _{2U |} 0.9 of this additional signal or a modified signal is to be generated.

In Figure 5 top half different load conditions are shown. Figure 1 shows that during the measuring time of two minutes, a number of slip revolutions or slip pulses has been reached, which is below the permissible number I _IU of four slip revolutions. In the diagram Il is shown that at the end of Meßzeittaktes t _in , actually reached the limit. In this case also no alarm occurs. In the load case shown in graph III, it can be seen that during the measurement time t _int at a time t _gim , the permissible number of slip revolutions l _iu i is already exceeded by the measured or calculated number of slip revolutions l _g , _m . An alarm signal is generated, ie the signal generator 27 responds. However, since the rotational speeds n, and n ₂ of the input all 13 and the output shaft 14 are still approximately the same, the signal is given the quality of being only a slow overload. In the load case shown in graph IV can be determined that after a first only a small number of slip rotations suddenly an increase and exceeding the allowable limit l, _u i takes place within the current Meßzeittaktes, wherein it has been found simultaneously that the rotational speeds n, and n ₂ of the input shaft 13 and output shaft 14 to a considerable extent deviate from each other, so that via the Quotientengrenzwertvergleicher 29 an additional signal is triggered, indicating that there is obviously a blockage. As a reaction of the operator, the shutdown of the drive or tractor 1 would have to be effected in order not to allow a break or an overload of the device 2 or the coupling 5 to follow.

In the diagram V, finally, a starting situation is shown. Although initially at the beginning of the Meßzeittaktes a larger number of slip revolutions I _011n , is determined, however, stabilizes the behavior so that no alarm signal is given.

In order to give the driver additionally also information about the degree of utilization of the driven device 2, a unit of the evaluation unit 22 is additionally assigned, which indicates the relative slip RS during a Meßzeittaktes t _In . The relative slip indicates how far the power limit of four permissible slip revolutions is utilized. The relative slip RS is calculated at the respective measuring time within a measuring time t _in , from the number of slip revolutions l _g , _{m determined} during the measuring time in relation to during this time

Measurement time elapsed time t _gam multiplied by this quotient of the time for a measurement time t _{in (} and the permissible number of slip revolutions l, _u] during this measurement time t _in , multiplied by 100%, thus indicating in% Slip is shown on the one hand in Figure 4 and on the other hand also with reference to the load states shown in the diagrams above in Figure 5. It can be seen that in the load case according to graph I, a relative slip RS and thus a utilization ridge with respect to The permissible slip of four revolutions in the measuring time cycle of 50% is reached at the limit load according to diagram IV a load factor of 100% and with the slow overload a value between 100 and 150. Here the driver can already well before the message "Überlr stung recognize from the RS value of about 125% that he his device or his Ku Due to the finding of a steep increase in the load condition according to graph IV, the driver can also see from the changed warning that the danger of a blockage exists. ^{1 In} connection with the diagram IV, which concerns the start, it can be seen that the relative limits in the measuring interval can be exceeded, but if they do not persist until the end of the first Meßzeittaktes, no warning signal is triggered.

The limit speeds for the definition of the quotient must each be newly determined or determined for the individual application. In the event of a blockade, the driver must be made very much aware of this condition, or it may even be provided that an automatic shutdown takes place via the evaluation unit 22 in order to avoid overheating of the friction clutch 5. The mode of action will be explained in more detail with reference to two practical examples. Two values are fixed values. These are the maximum permissible number of slip revolutions l _nl with four and the duration of the measurement time t _int with two minutes.

Further, it is a principle of the method according to the invention that a jeweils'neuer Meßzeittakt t starts _in when the allowable limit has been exceeded, and an alarm signal has been given. In general, however, a measuring time clock starts to run only when a slip is detected at all.

Example I: Approaching a device with a large mass to be accelerated This example applies to a shredder or similar machines:

Rated speed of the device: _{ner) n} = 1000 min " Starting speed of the tractor: n, = 400 min " ¹ Lead time: 'gladly = 1.3s

These predetermined realistic conditions mean that during the starting phase an average speed of 200min ^"1 is present. This is assumed that is approached with a relatively high tractor PTO speed, and in that the PTO speed remains constant during the starting process. During this very hard starting process is the limit of approved slip revolutions l, _u i just reached. the driver is displayed at a little harder starting, that he has overloaded the system. However, it is not made any "blockade message" because the output speed at the time of reaching the permissible number of slip revolutions Ui near the Input speed is

Example II: Milling or operation of a rotary harrow with short-term blocking For this example, the following working conditions were used:

Drive speed: ν = 6km / h = 1.67m / s PTO speed: η = 1000 min " ¹ = 16.67 s" ¹

If these working conditions are met, a warning message will be given in case of a blocking time of 0,25see. During this time a distance of 40cm is covered. This means that a response of the friction clutch 5 when driving over e.g. a strong solidified spot on the field, for example a stuck lane, which may be associated with heavy slippage of the friction clutch 5, still no "alarm" is given .. Only longer blockage times lead to error messages This type of alarm message can be accepted by the user.

These examples show that the chosen measuring time of two minutes and the maximum allowable number of four slip revolutions is sufficient for both long-term loading and by displaying the alarm when exceeding the slip limit during the measurement time the possibly occurring shock loads. The measuring time or the limit for the maximum allowable slip must be adapted to the respective coupling design to prevent overheating of the coupling can safely. For the tractor driver are three different Warnbzw. Display functions conceivable:

1. Alarm message for the driver with "slow" overloading of the device 2

- The permissible number of slip revolutions Ui is exceeded during a Meßzeittaktes.

- Output speed n ₂ is greater than 90% of the input speed n, (Q> 0.9)

There is ei -te warning z. B. with a 5Hz interval tone for a period of 2s.

2. Alarm message for the driver in case of blockage of the device ?

- The permissible number of slip messages Ui a Meßzeittaktes ti _nl ^; exceeded.

- the output speed is less than 90% of the input speed (Q _leg <Q <ui = 0.9)

There is a changed warning z. B. with a continuous tone of 8s or optionally a shutdown of the drive.

3. Display for the driver about the degree of utilization {utilization indicator 30) of the device 2

- Displayed is the percentage of the slip within a Meßzeittaktes based on the maximum allowable number of slip revolutions l, _u i during a Meßzeittaktes.

The following rule applies to this: RS relative slip

tint Duration of the measuring time clock

tg, _m Time since the beginning of the respective measuring time clock

I ₁ U ₁ Maximum permissible number of slip revolutions in the measuring cycle

l _gem currently measured number of slip revolutions in Meßzeittakt

The display can cause excessive load on the device 2 during a Meßzeittaktes t _inl a value of more than RS = 100% is displayed without the maximum allowable number of slip turns Li would have been reached. However, this information is an indication to the driver to reduce the driving speed, while maintaining this operation, the device overloaded during the Meßzeittaktes and thus the friction clutch 5 would be overheated. This is shown in Fig. 4. Also with reference to FIG. 3, the effect of the display can be seen.

The display allows the driver to get an idea of the utilization of his device 2. With appropriate use of this information and implementation in a suitable driving strategy, the machine utilization can be improved and thus the working speed can be optimized.

Claims (2)

A method of triggering a signal indicative of achieved preset load limits in the driveline of a tractor-driven, self-propelled or stationary agricultural machine having a torque limiting clutch whose input and output speeds are measured and summing the slip rotation corresponding to the speed difference, characterized in that the calculated during one from the first occurrence of a slip predetermined measuring time clock (t _int ) or during subsequent slip during one of the subsequent Meßzeittakte (t _int ) the calculated slip turns (l _gom ) when exceeding the predetermined allowable slip turns ( l _to i) trigger a signal, wherein when the signal is triggered in each case a new measuring time clock (t _int ) starts to run and that at the time of exceeding the permissible number of slip revolutions (U i) from the measured at that time drive speed (n,) and the output speed (n ₂ ) of the quotient is formed, wherein the input speed (n,) the denominator and the output speed (n ₂ ) forms the counter, and that the triggered signal is changed when falling below a predetermined quotient (Q _to i). 2. The method according to claim 1, characterized in that a comparison signal according to the function