IT202100014030A1 - METHOD AND APPARATUS FOR CHECKING AN ENGINE SUBJECT TO A PERIODIC LOAD - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

?METHOD AND APPARATUS FOR CHECKING AN ENGINE SUBJECT TO A PERIODIC LOAD?

TECHNICAL FIELD

The invention ? relating to a method and apparatus for controlling an engine, such as of a vehicle, especially a working vehicle such as an agricultural baler, harvester, tractor, straw walker, and the like.

BACKGROUND OF THE INVENTION

Work vehicles are notoriously equipped with external tools to perform various types of tasks.

The operation of some types of tools involves a reciprocating movement of components that are mechanically linked to a vehicle drivetrain, such as via a drive unit. power take-off (PTO, Power Take Off).

The transmission ? driven by a vehicle engine, for which the engine ? subjected to external load caused by the above-mentioned reciprocating components.

This external load? a periodic load which is added to the load associated with the normal progress of the vehicle on the fields.

Periodic loads generally cause inconvenience to the driver of the vehicle. Furthermore, the presence of periodic loads increases wear and tear and can even cause harm, under the worst conditions.

Therefore, the need is felt to increase the driving comfort of the vehicle. Furthermore, the need is also felt to improve the preservation of the engine and/or other vehicle components from wear and damage.

A goal of the invention ? satisfy at least one of the needs? above.

SUMMARY OF THE INVENTION

The target ? achieved with a method and apparatus for controlling an engine, in particular subject to periodic loading, as defined in the independent claims.

The dependent claims set forth particular embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred embodiment is described below, by way of non-limiting example, with reference to the attached drawings in which:

- Figure 1 ? a schematic plan view of a vehicle comprising an apparatus according to an embodiment of the invention,

- Figure 2 ? a line graph showing a signal in the time domain of the speed? output of a vehicle engine,

- Figure 3 ? a line graph showing the amplitude of the signal of Figure 2 in the frequency domain, e

- Figure 4 ? an amplitude Bode plot of a transfer function to be applied to the signal of Figure 2 in the frequency domain according to an embodiment of a method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In figure 1, the reference number 1 indicates a vehicle as a whole, specifically a work vehicle, in particular an agricultural tractor.

The vehicle 1 comprises an engine 2, a drive axle 3, and a transmission unit 4 configured to couple the engine 2 to the drive axle 3, such that the latter can be driven by the engine 2.

Does engine 2 have an output shaft or crankshaft 6, which ? an input of transmission group 4 and ? then connected to it.

The vehicle 1 further comprises a unit? PTO 7 and a PTO shaft 8 having respective ends? coupled to the unit? PTO 7 and the transmission group 4. In figure 1, the unit? PTO ? disposed on the back of the vehicle 1, but there? Not ? limiting; in reality?, the unit? PTO 7 can? be placed at the front or in an intermediate portion of the vehicle 1.

The unit? PTO 7 includes a PTO 9 output and a PTO 10 clutch which can? be engaged and disengaged to selectively connect and disconnect PTO output 9 and PTO shaft 8.

The vehicle 1 further includes an implement 11, such as a baler, attached to the unit. PTO 7, specifically at the PTO 9 outlet.

The tool 11 has an operation which implies the occurrence of a periodic load exerted on the engine 2. The periodic load ? transmitted from the implement to the engine 2 through the PTO shaft 8 and the transmission unit 4. In particular, the implement 11 has a component not shown which has a reciprocating movement during its operation.

The transmission assembly 4 includes a transmission device 12 for selectively connecting and disconnecting the crankshaft 6 and the drive axle 3.

The transmission device 12 can? include a gearbox and/or a hydrostatic transmission. Possibly, the transmission device 12 can? also include one or more clutches.

The vehicle 1 further comprises a transducer T1 configured to detect an amount? indicative of a speed? output of the engine 2 and generate a related signal in the time domain, such as the one shown in figure 2. For clarity, the term speed? engine will be? used below to identify this speed? of output.

Preferably, the quantity? detected ? directly indicative of the speed? of engine, what ? for example the speed? of the crankshaft 6, in other words. In particular, the quantity can? be a quantity electricity such as a voltage or a current proportional to the speed? of engine. However, other quantities? can be detected alternatively, such as a speed? of the shaft PTO 8, one speed? output or input of the transmission device 12, a speed? of the motor axle 3, a speed? of the exit PTO 9, and the like, or a quantity? corresponding proportional electric power, such as a voltage or a current. Indeed, not all quantities? mentioned are indicative of the speed? of engine, at least assuming that the corresponding components are respectively connected to the engine 2, ie assuming for example that the clutch 10 is engaged provided that? the quantity? is relative to the output PTO 9. Nevertheless, pi? in general, the quantity? detected pu? be indicative of a speed? of any component of the vehicle 1, provided? such speed? is in turn indicative of the speed? motor, either directly or indirectly, for example via a mechanical connection between motor 2 and the component.

The vehicle 1 further comprises a unit? controller 20 configured to control the motor 2 and to acquire the signal in the time domain, for example from the transducer T1. Alternatively, the unit? control 20 pu? acquiring the signal in the time domain through an estimation, for example by extracting information from the control of engine 2 or by an observer. In the latter case, the signal coming from the transducer T1 can? be provided to the observer.

The unit? of control 20 ? configured to control the engine 2 on the basis of a reference, which can? be a speed reference? or couple. Does the reference define a control input to the unit? control 20 and pu? preferably be stored within it. Pi? precisely, the unit? controller 20 comprises a controller or a control logic block for controlling the motor 2. The controller can? be designed as an open loop controller or a closed loop controller. In the first case, the controller receives the reference as direct input; otherwise, the controller receives as input a difference between the reference and a corresponding measured feedback.

Does the control input affect the actual trend of the quantity? detected or estimated above with a time delay which depends on the characteristics of the controller, of the engine 2, and possibly, of the transmission unit 4, of the PTO shaft 8, and of the unit? PTO 9, based on the component to which the quantity? ? related. Therefore, ? It is possible to define a functional relationship between the control input and the quantity. In the linear case, the functional relationship corresponds to a transfer function in the frequency domain. Preferably, the functional relationship ? stored in the unit? control 20.

The functional relationship can be estimated or identified theoretically or based on experimental data, possibly using black or gray box models.

The unit? of control 20 ? configured to transform the acquired time domain signal by means of a suitable transform, preferably stored in the unit? control 20. In other words, the unit? of control 20 ? configured to compute a first transformed signal by applying the transform to the acquired time domain signal.

The right transformation? designed to decompose the signal in the time domain into a superposition of basic waves each associated with one or more? corresponding frequencies.

Specifically, the suitable transform ? the Fourier transform, in particular in the discrete form, pi? in particular implemented by the unit? of control 20 with the fast Fourier transform algorithm. Here, the basic waves are pure sine waves, each associated with a single corresponding frequency. The first transformed signal pu? be expressed as a linear combination of the sinusoids. A result of applying the Fourier transform ? illustrated for example in Figure 3, in which the amplitudes or magnitudes of the complex coefficients of the linear combination are shown in association with the corresponding frequencies.

Alternatively, the suitable transform can be a wavelet transform, possibly once again in the discrete form. In this case, the basic waves are a series of wavelets associated respectively with contiguous frequency bands.

In general, for the suitable transform ? You can use any known definition of basis waves, such as sine (cosine) wave packets, Wilson bases, chirplets, warped bases, hyperbolic cross bases, and the like.

The suitable transform pu? Also be used to transform control input and quantity. In this case, a gain function corresponding to the above functional relationship can? be defined by the control input transformed to the quantity? transformed. The gain function ? the transfer function in the linear case. Preferably, the unit? control knob 20 stores the gain function. For example, the transfer function has a Bode plot that ? shown partially in Figure 4 (amplitude only).

Furthermore, the unit of control 20 ? configured to update the first transformed signal, i.e. to calculate a second transformed signal, subjecting the first transformed signal to low-pass filtering based on a frequency threshold, preferably stored in the unit? control 20. For example, the frequency threshold ? less than 10Hz, especially less than 2Hz. However, the optimal value for the frequency threshold essentially depends on the characteristics of the vehicle 1. This optimal value can? be obtained experimentally, for example.

Low-pass filtering can be performed by means of a typical low-pass filter of any order with a polynomial transfer function and a cutoff frequency equal to the frequency threshold. Low-pass filtering can also be performed by removing from the overlay all base waves associated with at least one frequency greater than the frequency threshold or with frequencies that are partially (e.g. a given percentage of the frequencies) or wholly greater than the frequency threshold.

Furthermore, the unit of control 20 ? configured to compute a third transformed signal by applying the inverse of the gain function to the second transformed signal. In this way, the unit? control 20 calculates a signal that corresponds to the control input that ? necessary to obtain the detected or estimated trend of the quantity.

The unit? of control 20 ? further configured to compute an additional time domain signal from the third transformed signal based on the inverse of the suitable transform. The further signal in the time domain is calculated by determining a phase opposition with respect to a signal obtainable through the direct application of the inverse of the transform to the third transformed signal. There? can? be achieved in a plurality? of ways.

For example, the unit control 20 pu? use a properly designed phase shifter to apply a pure delay to the signal obtained through the above direct application. In this case, the phase shift ? consistently equal to -180 degrees for all frequencies.

Another possible way includes removing the base wave associated with a null frequency in the third transformed signal and then applying the inverse of the transform to the negative of the third transformed signal after removal. Then, the removed wave, corresponding to the average of the originally acquired signal, is added to the result of the inverse transform.

Also, preferably, the originally acquired signal can? acquired directly without its mean, i.e. after a subtraction of the mean. In this case, isn't it? basic wave removal required; the further signal in the time domain is then obtained by applying the inverse of the transform to the negative of the third transformed signal.

The unit? of control 20 ? configured to determine the control input or reference based on the further signal in the time domain.

Where the originally acquired signal has a zero mean, which corresponds to the subtraction of the mean in the acquisition, the reference ? preferably the sum of a desired target and the further time domain signal, also having zero mean. Otherwise, the reference pu? be defined directly by the further signal in the time domain. In this way, ? is it possible to compensate for an unwanted oscillation in the quantity? due to periodic loading.

Therefore, the unit of control 20 ? configured to control motor 2 based on the determined control input, as mentioned briefly above.

Therefore, the unit control 20 pu? implement or execute a method to control motor 2; the method has the following steps:

to. acquire the signal in the time domain,

b. calculate the first transformed signal by applying the suitable transform to the time domain signal,

c. calculate the second transformed signal by low-pass filtering the first transformed signal according to the frequency threshold,

d. calculate the third transformed signal by applying the inverse of the gain function to the second transformed signal,

And. calculate the further time domain signal from the third transformed signal,

f. determine the control input based on the time domain signal, e

g. control motor 2 based on the determined control input.

Preferably, all steps a-g as a whole are completed upon specific request from the driver of the vehicle 1. In particular, the vehicle 1 comprises a control element 14 which can be used by the driver, for example manually. Control element 14 can? be a button, knob, lever, touch panel, and the like. Control element 14 ? configured to issue a command signal, such as when used or when not used. The unit? of control 20 ? configured to determine whether the command signal is output. Thus, steps a-g are completed entirely, as a whole, after the determination of the emission has had a predetermined outcome, preferably stored in the unit? control 20. For example, are steps a-g completed entirely, as a whole, after the command signal ? been issued or, according to a different alternative, not issued.

In particular, the command element 14 outputs the command signal when used and steps a-g are completed after the command signal is issued.

In practice, the control of motor 2 based on the control input determined in phase f ? appropriate when the periodic load acts on the engine 2. Otherwise, this control can? be properly omitted. Therefore, the driver can? use or not use the control element 4 appropriately according to the intended presence or absence of the periodic load. The control element 14 can? even be used by the unit? controller 20 automatically based on information extracted from a sensing device configured to detect whether the periodic load is acting or not acting. Control element 14 ? used or, according to the different alternative, not used to request the completion of all phases a-g when the information is indicative that the periodic load is actually acting.

Alternatively or additionally, the vehicle 1 also comprises another control element 15 which can be used by the driver, in particular manually, to control the disengagement of the clutch 10. For example, the control element 15 can? be a clutch pedal, button, lever, knob, and the like.

The control element 15 can? also be used by the driver to affect the entire completion of steps a-g. In this case, the disengagement of the clutch 10 must be considered as a request to prevent the completion of steps a-g.

The operating element 15 ? configured to issue a command signal when it commands the disengagement of the clutch 10 or vice versa, according to an alternative. The unit? of control 20 ? configured to determine whether the command signal is output. The unit? of control 20 prevents the overall completion of steps a-g when the determination detects that the clutch 10 ? disengaged; this means that phases a-g can be fully completed, overall, only if the determination of the emission has a further predetermined result, or after it has had it, in particular corresponding to the engagement of the clutch 10, i.e. the opposite situation of the disengagement of the clutch 10. In this case, steps a-g can be completed entirely, overall, only if the clutch 10 ? grafted.

However, unlike the control element 14, the control element 15 cannot? be used to actively request completion of all steps a-g, collectively, but only to prevent such completion.

Advantageously, each of the phases a-f can? be anticipated while the clutch 10 ? disengaged, i.e. before the further predetermined outcome occurs. Here, preferably, any of the calculated transformed signals (from the first to the third) can? be stored in the unit? of control 20 and advantageously exploited while the clutch 10 ? engaged, i.e. after you ? verified the further predetermined outcome.

Therefore, specifically, at least one of the phases a-f and the phase g are respectively performed before the occurrence and after the occurrence? verified the further predetermined outcome. This means that if some of the steps af are performed before the further predetermined outcome, the other steps will be performed after the further predetermined outcome together with the step g. The specific concept of this paragraph can? be applied preferably, mutatis mutandis, in relation to the control element 14. That is, at least one of the phases a-f ? performed before the unit? of control 20 determines the predetermined outcome for the command signal emission by the command element 14. Phase g ? performed after that yes ? verified the predetermined outcome.

According to particular embodiments, the originally acquired time-domain signal can be considered ideally divided into a series of successive portions. Pi? precisely, the portions are respectively associated with a series of contiguous time intervals, i.e. without discontinuity? between any two successive intervals.

Each portion can include a selected number of samples, the number of which ? stored preferably in the unit? control 20; more preferably, the portions all have the same number of samples. Possibly, the number pu? be set in the unit? controller 20, possibly by means of an appropriate control of the vehicle 1.

In these embodiments, the first transformed signal can also be processed. be considered ideally subdivided into a series of successive transformed portions corresponding to the portions of the signal in the time domain. Each portion processed ? the result of transforming the corresponding portion of the signal in the time domain by means of the suitable transform.

In general, the first transformed signal ? a complex signal, i.e. it belongs to a complex domain. Thus, the samples of the first transformed signal have respective amplitudes and phases. In other words, the first transformed signal has an amplitude and a phase.

Considering, for example, the portion pi? recent or current series, compared to the time, the unit? of control 20 ? configured to extract the average of the considered portion and the average of the immediately previous portion.

In particular, the amplitude of the transformed portion corresponding to the considered portion, the most? recent of the series) ? scaled by the ratio of the extracted averages. Pi? precisely, for example, the ratio between the average of the previous portion and the average of the portion considered? multiplied by the width. Does this mean that the unit? of control 20 ? configured to perform scaling during the computation of the first transformed signal, especially after directly applying the transform to the time domain signal.

In this way, the variations of the average of the quantity, for example due to variations of the average of the reference, in turn preferably due to a request from the driver, are not taken into account in the compensation of the periodic load. This ? particularly appropriate when the periodic load ? "based on the angle", ie the periodicity? of the load ? in relation to the angular rotation of the crankshaft 6 (load peaks occur for precise angles of rotation of the crankshaft 6). This ? the case, for example, when the tool 11 ? a baler.

Furthermore, regardless of the scaling procedure just mentioned, the amplitude of the last transformed portion of the series ? averaged with the amplitude of at least one previous transformed portion. Advantageously, the last transformed portion ? averaged with the amplitude of a selected number of previous transformed slices in succession. For example, the dialed number ? stored in the unit? control 20. Preferably, this number pu? be set in the unit? of control 20, for example by means of an appropriate command of the vehicle 1. The number should be appropriately more? large according to loads that are more irregular. In fact, a greater number corresponds to a greater importance of the past memory in relation to the progress of the quantity.

Preferably, the average ? a weighted average, for example to give more? importance to the portions pi? of the acquired time domain signal.

The scaling can be required by the driver when the periodic load is supposed to be angle based. The vehicle 1 comprises a control element 16 which ? usable by the driver, in particular manually. Preferably, the control element 16 is distinct from the command element 14, but pu? be analogous to it and have analogous functioning. In fact, the control element 16 ? configured to issue a command signal, such as when used or when not used. Furthermore, the operating element 16 can be a button, knob, lever, touch panel, and the like.

Alternatively, the control element 16 can? coincide with the control element 14; in this case, distinct command signals are issued based on a different way of using the same command element 14.

The unit? of control 20 ? configured to determine whether the command signal of the control element 16 is output. Therefore, the scaling ? performed only after the emission determination has had a predetermined outcome, preferably stored in the unit? control 20. For example, the scaling ? performed after the control signal of the control element 16 ? been issued or, according to an alternative, not issued.

In particular, the command element 16 emits the command signal when used and the scaling ? performed after the command signal is output.

Advantageously, the completion of all phases ag in the complex ? subordinate to a verification step in which the occurrence of an operating parameter of or associated with engine 2, or of or associated with vehicle 1, satisfies a predetermined relationship with a threshold. In fact, steps a-g are fully completed only after the verification step has been successful.

The reason for that? consists in the fact that some operating parameters of the vehicle can temporarily influence the trend of the quantity, thus introducing irregularities? on the acquired time domain signal. These irregularities? they cannot be compensated for correctly by carrying out steps a-g, which are designed to compensate for the effects of periodic loads. Therefore, at least one of the phases a-g (in particular the phase g) is not? performed until? the unit? control 20 does not verify that the predetermined relationship ? been satisfied.

The unit? of control 20 ? configured to perform the verification phase. Preferably, the unit? controller 20 stores the predetermined relationship.

In particular, the verification phase ? performed after the unit? control element 20 determined the predetermined outcome for determining the output of the control signal by the control element 14 (and/or the control element 16).

In other words, the verification step takes place only after a request from the driver for the completion of steps a-g as a whole, in particular of step g.

Therefore, the unit controller 20 implements a state machine with four states. A first state? the disabled state, where at least one of the phases a-g, in particular the phase g, is not ? performed. When the operator requests the completion of all steps a-g altogether (i.e. using or not using the control element 14 or 16), a second state is implemented. The second state? the verification state, in which the verification phase occurs. If the verification phase is successful, a third state is implemented. The third estate? the controlled state, where all steps a-g are completed in the complex. A fourth state? the disabled state again. The fourth estate? implemented after the third state if the driver requests it, i.e. if the driver requests the interruption of phase g.

For example, the driver can requesting the interruption or impediment of step g accordingly using the control element 14 or the control element 16, depending on the one used to request the completion of steps a-g.

Therefore, the operating element 14 or 16 ? configured to issue an interrupt signal. The unit? of control 20 ? configured to cause the break signal to be output to break or prevent phase g when the break signal is output.

The operating parameter? one of the parameters that can? introduce irregularities? on the acquired time domain signal.

Pi? precisely, the operating parameter ? one of - a temperature of a fluid to condition the engine 2,

- a temperature of a fluid to lubricate and/or condition the transmission unit 4,

- a status parameter of an engine aftertreatment system 2,

- a speed? advancement of vehicle 1, e

- a load acting on motor 2.

In particular, when the parameter ? the temperature of the fluid to condition the engine 2, the positive result ? what the temperature? greater than the threshold.

When the parameter ? the fluid temperature for the transmission group 4, the positive outcome ? what the temperature? greater than the threshold.

When the parameter ? the speed? or the load, the success ? that the speed? or the load? greater than the threshold.

The unit? control 20 is part of an apparatus for controlling the engine 2.

In view of the above, the advantages of the method of the apparatus according to the invention are evident.

The calculations performed by the unit? of control 20 allow an estimation of the periodic load that acts on the motor 2. Furthermore, the unit? controller 20 commands the motor to compensate for the estimated periodic load, thereby eliminating dangerous torsional oscillations which would normally be caused by the periodic load.

The vibration mitigation provides greater driving comfort for the driver and less wear on the components of the drive group 4.

The unit? of control 20 ? capable of performing the estimation independently of the tool 11 actually used by vehicle 1.

Also, engine control 2 ? robust in relation to irregularities?. The unit? of control 20 ? programmed to compensate for periodic loads without interfering with a very rapid frequency component of the overall load acting on motor 2.

In the end, ? clear what? It is possible to make modifications to the described method and apparatus which do not extend beyond the scope of protection defined by the claims.

In particular, the described characteristics of the unit? controllers 20 can be freely combined with each other.

Clearly, steps a-g are performed completely after the predetermined results have occurred in relation to the emissions of the control signals by the control elements 14, 16, but before the driver requests an interruption or an impediment of the step g using the same control elements 14, 16 appropriately.

The method and operation of the apparatus can also be performed outside a vehicle. In general, the method of the apparatus are applicable to compensate for periodic loads acting on an engine, which can? also not be installed on a vehicle.

Claims (11)

1. Method for controlling a motor (2), the method including the steps of to. acquire a first signal in the time domain related to a quantity? indicative of a speed? motor output (2), b. calculate a first transformed signal by applying a transform to the first signal in the time domain, in which the transform ? designed to decompose the signal in the time domain into a superposition of basic waves each associated with one or more? matching frequencies, c. calculate a second transformed signal by low-pass filtering of the first transformed signal according to a frequency threshold, d. calculate a third transformed signal by applying a first gain function to the second transformed signal, where the first gain function ? the inverse of a second gain function mapping a first variable to a second variable, wherein the first and second variable are respectively defined by a transformation of a third and fourth variable by means of said transform, wherein the third and the fourth variable are a control input to control the engine (2) and said quantity?, And. calculate a second signal in the time domain from the third signal transformed, where the second signal in the time domain ? in phase opposition with respect to a third signal in the time domain obtainable by applying the inverse of said transform to said third transformed signal, f. determining said control input based on the second time domain signal, e g. control the motor (2) according to the control input determined in step f. The method according to claim 1, further comprising the step of h. determine if a first command signal ? issued by a first control element (14, 15), wherein all steps a-g are completed after step h has a first predetermined outcome. 3. A method according to claim 2, wherein one of the steps a-f and step g are respectively performed before and after the occurrence of? verified the first predetermined outcome. The method according to any one of the above claims, further comprising the steps of the. extract a first average of a first portion of the first signal in the time domain, j. extract a second average of a second portion of the first signal in the time domain, where the first portion immediately follows the second portion, wherein the first transformed signal has a first and second transformed portion respectively calculated by transforming the first and second portion by means of said transform, in which the first transformed portion belongs to a complex domain and in which the amplitude of the first transformed portion ? climbing a ratio between the second grade and the sixth grade. The method according to claim 4, further comprising the step of k. determine whether a second control signal is output from a second control element (16), in which the amplitude of the first portion transformed ? scaled only after phase k has had a second predetermined outcome. The method according to any preceding claim, wherein the first time domain signal has a series of successive portions, and wherein the first transformed signal has a series of successive transformed portions computed respectively by transforming said series of successive portions, in which the transformed portions belong to a complex domain, in which the amplitude of the last of the transformed portions ? been averaged with the amplitude of at least one previous slice among the transformed slices. The method according to any one of the preceding claims, further comprising the step of L. check whether an operating parameter associated with the engine (2) satisfies a predetermined relationship with a threshold, where all steps a-g are completed only after step l is successful. 8. Method according to claim 7, wherein the operating parameter ? one between - a temperature of a first fluid to condition the engine (2), - a temperature of a second fluid to lubricate and/or condition the transmission means (4, 12, 13) driven by the motor (2), - a status parameter of an engine aftertreatment system (2), - a load acting on the motor (2). The method according to any one of claims 1 to 6, wherein the engine (2) constitutes a part of a vehicle (1), the method further comprising the step of 1. check whether a vehicle operational parameter (1) satisfies a predetermined relationship with a threshold, where all steps a-g are completed only after step l is successful. 10. Method according to claim 9, wherein the operating parameter ? one between - a temperature of a second fluid for lubricating and/or conditioning transmission means (4, 12) of the vehicle (1), - a speed? vehicle forward speed (1). 11. Apparatus for controlling an engine (2), the apparatus comprising a unit? controller (20) programmed to implement the method according to any one of the above claims.