Patent Application
20240198994
This application claims the benefit of and right of priority under 35 U.S.C. § 119 to German Patent Application no. 10 2022 213 834.1, filed on 19 Dec. 2022, the contents of which are incorporated herein by reference in its entirety.
The invention relates to a method for controlling the brakes of a vehicle combination, which consists of a tractor vehicle with a hydraulic or pneumatic brake system and at least one trailer vehicle that can be coupled to the tractor vehicle, with a pressure-controlled pneumatic brake system, and in which an electronically controlled brake control valve arranged in the tractor vehicle is used, which comprises at least two magnetic switching valves that can be actuated by an electronic control unit, the valves being in the form of an inlet valve and an outlet valve, wherein by means of the brake control valve a brake control pressure can be produced in a brake control line from a brake control outlet of the brake control valve, which line leads to a “Brake” coupling head of the tractor vehicle or to a trailer brake valve of the trailer vehicle and/or to a “Brake” coupling head at the rear of the trailer vehicle, and in which, to determine the current status of the trailer, it is determined whether the tractor vehicle is in fact connected to a trailer vehicle and/or how large the line volume of the brake control line is.
To be able to control a braking process of a vehicle combination in an optimum manner, knowledge of the current status of the trailer is useful, i.e., whether at least one trailer is coupled or no trailer vehicle is coupled to the tractor vehicle. It is true that whether or not a trailer vehicle is coupled can be recognized with any trailer plug-socket, indirectly by the prescribed monitoring of the flashing light on the trailer, or by virtue of a special association of two contacts of a 13-pole trailer plug-socket, with reference to whether the on-board electrical system of the trailer is or is not connected by a plug connection to the on-board electrical system of the tractor vehicle. However, the electric contacts of the plug on the trailer side and/or the socket on the tractor side can become corroded or dirty, or the signal line concerned can be broken at some point, so that an alternative determination of the trailer's status is advantageous.
Furthermore, for an optimum control of a braking process it is necessary, when a trailer is coupled on, to know the line volume of the brake control line running from the brake control outlet of the trailer control valve in the tractor vehicle to the brake control inlet of the trailer braking valve in the trailer vehicle, in order to be able to rapidly build up a specified brake control pressure in the brake control line for a largely delay-free actuation of the wheel brakes of the trailer vehicle. The trailer brake valve of the trailer vehicle is at least close to the tow bar or the hitch plate and therefore relatively far forward, which results in a relatively small line volume of the brake control line. However, since an agricultural tractor can tow up to two trailer vehicles, agricultural trailers are often provided at the rear with a trailer coupling and two pneumatic coupling heads for coupling a second trailer vehicle and for connecting its brake system. The brake control line of such a trailer vehicle runs from the coupling head concerned to the connection to the coupling head of the tractor vehicle, on the one hand as far as the trailer brake valve, and on the other hand, as far as the coupling head at the rear of the trailer vehicle, and this results in a comparatively large line volume of the brake control line.
In a method known from DE 10 2020 106 448 A1 for controlling the brakes of a vehicle combination, to enable an actuation of the wheel brakes with only a small delay it is provided that at the beginning of a braking process a pressure pulse is delivered that exceeds the brake control pressure to be built up, wherein the level and/or the duration of the pressure pulse is determined as a function of the line volume of the brake control line determined. The line volume of the brake control line is determined after every new start of operation of the tractor vehicle, in that when the wheel brakes are released the duration of the pressure drop and/or the average pressure gradient during the pressure drop in the brake control line are determined by sensor means and compared with stored reference values. With reference to the line volume determined, it is also recognized whether or not a trailer vehicle is coupled on. The size and/or duration of the pressure pulse delivered are increased with increasing line volume of the brake control line.
In DE 197 44 066 B4 a method is described for recognizing the operation of a trailer in a motor vehicle, in which method, when the brakes are actuated the pressure build-up in the brake control line leading to the trailer vehicle is detected by sensor means and from that a characteristic magnitude is determined, with reference to which trailer operation can be recognized. As the characteristic magnitude, the pressure gradient during the pressure build-up in the brake control line is determined and compared with a target pressure gradient specified by the actuation of the brake pedal in the tractor vehicle. If the pressure gradient is lower than the target pressure gradient, trailer operation is recognized, i.e., the fact that a trailer is coupled on.
From EP 2 918 469 B1 a device and a method for recognizing a coupled-on trailer vehicle are known, wherein it is provided that after the release of the wheel brakes the brake control pressure in the brake control line leading from the trailer control valve of the tractor vehicle to the “Brake” coupling head or to the trailer brake valve of a brake control valve of a coupled trailer is determined by sensor means. From the variation of the brake control pressure during the pressure drop, the time interval until a specified pressure value has been reached is determined and compared with a predetermined time value. If the time duration of the pressure drop is shorter than the predetermined time interval, it is recognized that no trailer is coupled on. If the time duration of the pressure drop equals or exceeds the predetermined time value, then it is recognized that a trailer vehicle is in fact coupled on.
The purpose of the present invention, then, is to propose a method for controlling the brakes of a vehicle combination, of the type mentioned to begin with, in which method at least one alternative option for determining the trailer status of a tractor vehicle and the line volume of the brake control line is indicated.
This objective is achieved by methods with the characteristics disclosed herein. Advantageous further developments of the methods will be apparent in light of the present disclosure.
Accordingly, the invention relates to a method for controlling the brakes of a vehicle combination consisting of a tractor vehicle with a hydraulic or pneumatic brake system and at least one trailer vehicle that can be coupled to it and that comprises a pressure-controlled pneumatic brake system, and in which an electronically controlled brake control valve in the tractor vehicle is used, which valve comprises at least two magnetic switching valves that can be actuated by an electronic control unit, these valves being in the form of an inlet valve and an outlet valve, such that by means of the brake control valve a brake control pressure can be produced in a brake control line running from a brake control outlet of the brake control valve to a “Brake” coupling head of the tractor vehicle or to a trailer brake valve of the trailer vehicle and/or a “Brake” coupling head at the rear of the trailer vehicle, and in which method, to determine the current trailer status, it is determined whether the tractor vehicle is connected to a trailer vehicle and/or how large the line volume of the brake control line is.
To achieve the stated objective, it is provided that a target pressure to be produced in the brake control line is specified, that the target pressure is produced in the brake control line by pulse-like openings of the inlet valve and/or pulse-like openings of the outlet valve, and that the brake control pressure in the brake control line is measured by sensor means during the pressure build-up, and that from the pressure variation with time of the brake control pressure and/or the variation with time of the switching states of the inlet valve and/or the outlet valve until the target pressure has been reached, a characteristic value is determined for the trailer status of the tractor vehicle and/or the line volume of the brake control line and compared with a reference value stored in a data memory of the control unit, and depending on the result of the comparison, the trailer status of the tractor vehicle and/or the line volume of the brake control line are determined.
Thus, the invention starts from a vehicle combination consisting of a tractor vehicle with a hydraulic or pneumatic brake system and at least one coupled-on trailer vehicle with a pressure-controlled pneumatic brake system. In the vehicle combination, by means of an electronically controlled brake control valve arranged in the tractor vehicle, which valve comprises at least two magnetic switching valves, namely an inlet valve and an outlet valve that can be controlled by an electronic control unit, a brake control pressure can be produced in a brake control line that runs from a brake control outlet of the brake control valve to a “Brake” coupling head of the tractor vehicle or to a trailer brake valve of the trailer vehicle and/or a “Brake” coupling head at the rear of the trailer vehicle.
By specifying a target pressure and producing it in the brake control line by pulse-like openings of the inlet valve and/or pulse-like openings of the outlet valve, until the target pressure is reached, there is an increase of the brake control pressure and a plurality of switching states of the inlet valve and/or the outlet valve with which at least one characteristic value can be determined, this value characterizing the trailer status of the tractor vehicle and/or the line volume of the brake control line.
The trailer status indicates whether a trailer vehicle is coupled on or whether no trailer vehicle is coupled on. By comparing the characteristic value with at least one reference value determined beforehand as a function of the trailer status of the tractor vehicle and/or the line volume of the brake control line and stored in a data memory of the control unit, the trailer status of the tractor vehicle and/or the line volume of the brake control line can be determined. The brake control line can be vented by opening pulses of the inlet valve and/or the outlet valve, which have a variable pulse width and/or a variable time interval between the pulses. In this case the pulse width at the start of the venting process is made relatively large and with increasing approach of the brake control pressure to the target pressure it is reduced. In contrast, the pulse separation at the start of venting the brake control line is made relatively small and is increased with increasing approach of the brake control pressure to the target pressure.
For that purpose, according to a first method variant it is provided that the pulse widths PWIV and PWOV of the inlet and outlet valves are determined until the target pressure pZ has been reached, and in each case separately they are added to give a pulse width sum Σ PWIV for the inlet valve and a pulse width sum Σ PWOV for the outlet valve, and by subtracting the pulse width sum Σ PWOV for the outlet valve from the pulse width sum ΣPWIV for the inlet valve a pulse width sum difference Σ PWIV−Σ PWOV is determined as a characteristic value, and by a comparison of the current pulse width sum difference Σ PWIV−Σ PWOV with pulse width sum difference values determined beforehand as reference values for various line volumes of the brake control line and stored, the current trailer status of the tractor vehicle and/or the current line volume VBC of the brake control line are determined.
This first method variant, and also the three method variants described below, utilize the effect that the venting of the brake control line until the target pressure has been reached takes a long time, indeed the more so the longer the brake control line and the larger its line volume. Correspondingly, to reach the target pressure opening pulses of the inlet valve with larger pulse widths and/or more opening pulses of the inlet valve are needed, and/or the time to reach the target pressure is longer, the longer is the brake control line and the larger is its line volume.
According to a second method variant, it is provided that the opening pulse PIV of the inlet valve and/or the opening pulse POV of the outlet valve until the target pressure pZ is reached, is/are determined and summed to obtain an opening pulse number nP as a characteristic value, and by comparing the current opening pulse number with opening pulse number values determined beforehand and stored for various line volumes of the brake control line as reference values, the current trailer status of the tractor vehicle and/or the current line volume VBC of the brake control line are determined.
According to a third method variant, it is provided that the number of opening pulses PIV, POV of the inlet valve and the outlet valve until the target pressure pZ has been reached is detected, and these are added separately to obtain a number of opening pulses Σ nP_IV for the inlet valve and a number of opening pulses Σ nP_OV for the outlet valve, and by subtracting the opening pulse number Σ nP_OV for the outlet valve from the opening pulse number Σ nP_IV for the inlet valve, a pulse number difference (Σ nP_IV−Σ nP_OV) is determined as a characteristic value, and by a comparison of the current pulse number difference Σ nP_IV−ΣnP_OV with pulse number differences determined beforehand and stored for various line volumes of the brake control line as reference values, the current trailer status of the tractor vehicle and/or the current line volume VBC are determined.
A fourth method variant provides that the time period Δpz until the target pressure pZ has been reached is determined and forms a characteristic value as the pressure build-up time, and by comparing the current pressure build-up time Δpz, with pressure build-up times determined beforehand and stored for various line volumes of the brake control line as reference values, the current trailer status of the tractor vehicle and/or the current line volume VBC of the brake control line are determined.
In a fifth method variant, the effect is utilized that in the air column of the compressed air enclosed in the brake control line pressure oscillations are excited by the pulse-like opening of the inlet valve and/or by the pulse-like opening of the outlet valve, the number and amplitude of these oscillations differing as a function of the length and line volume of the brake control line. Accordingly, in this method variant it is provided that the number and/or the average amplitude of pressure oscillations of the brake control pressure pBC until the target pressure pZ has been reached is determined as a number of oscillations nS and/or an average oscillation amplitude AS_m that forms a characteristic value, and by comparing the current oscillation number nS and/or the current oscillation amplitude AS_m with oscillation number values and/or oscillation amplitude values determined beforehand and stored for various line volumes of the brake control line as reference values, the current trailer status of the tractor vehicle and/or the current line volume VBC of the brake control line are determined.
In a further development of the method variants, it is provided that the trailer status as regards a trailer vehicle that is not coupled is recognized if the current characteristic value Σ PWIV−Σ PWOV, nP, Δpz, nS, AS_m, matches to within a specified tolerance a reference value determined when a trailer vehicle is not coupled, and the trailer status as regards a coupled trailer vehicle is recognized if the current characteristic value Σ PWIV−Σ PWOV, nP, Δpz, nS, AS_m is larger than the reference value determined when a trailer vehicle is not coupled.
In addition, it can be provided that the line volume VBC of the brake control line is determined as the line volume of a brake control line extending as far as the “Brake” coupling head, if the current characteristic value Σ PWIV−Σ PWOV, nP, Δpz, nS, AS_m matches, to within a specified tolerance, the reference value determined when a trailer vehicle is not coupled.
Furthermore, it can be provided that the line volume VBC of the brake control line is determined as the line volume from a reference value determined when a trailer vehicle is coupled, if the current characteristic value Σ PWIV−Σ PWOV, nP, Δpz, nS, AS_m matches, to within a specified tolerance, the reference value concerned, or is determined by interpolation between two line volume values from two reference values determined when a trailer vehicle is coupled, if the current characteristic value Σ PWIV−Σ PWOV, nP, Δpz, nS, AS_m lies between the two reference values concerned.
A process sequence independent of the embodiments mentioned above also relates to a method for controlling the brakes of a vehicle combination which consists of a tractor vehicle with a hydraulic or pneumatic brake system, and at least one trailer vehicle that can be coupled on and which has a pressure-controlled pneumatic brake system, and in which an electronically controlled brake control valve arranged in the tractor vehicle is used, which valve comprises at least two magnetic switching valves that can be controlled by an electronic control unit and are respectively in the form of an inlet valve and an outlet valve, wherein by means of the brake control valve a brake control pressure can be produced in a brake control line that runs from a brake control outlet of the brake control valve to a “Brake” coupling head of the traction vehicle or to a trailer brake valve of the trailer vehicle and/or to a “Brake” coupling head at the rear of the trailer vehicle, and in which, to determine the current trailer status, it is determined whether the tractor vehicle is in fact coupled to a trailer vehicle and/or how large the line volume of the brake control line is.
To achieve the stated objective of the invention, in this method it is provided that a pneumatic pressure pulse with a fixed opening duration ΔtIV of the inlet valve to be delivered into the brake control line is specified, and that the pressure pulse is produced by pulse-like opening of the inlet valve into the brake control line, and that the brake control pressure pBC present in the brake control line after a predetermined time interval ΔtP since the inlet valve was closed is determined as a residual pressure ΔpR by sensor means, and that the residual pressure ΔpR is compared with at least one reference pressure value determined beforehand as a function of the trailer status of the tractor vehicle and/or the line volume of the brake control line and stored in a data memory of the control unit, and that depending on the result of the comparison, the trailer status of the tractor vehicle and/or the line volume VBC of the brake control line are determined.
In this case, the effect utilized is that the residual pressure remaining after a controlled pressure pulse becomes progressively lower with increasing length and correspondingly increasing line volume of the brake control line. Thus, it can be provided that the trailer status as regards an uncoupled trailer vehicle is recognized if the current residual pressure ΔpR matches, to within specified tolerance, a reference pressure value determined when no trailer vehicle is coupled, and the trailer status as regards a coupled trailer vehicle is recognized if the current residual pressure ΔpR is lower than the reference pressure value determined without a coupled trailer vehicle.
Moreover, it can be provided that the line volume VBC of the brake control line is determined as the line volume of a brake control line that runs to the “Brake” coupling head, if the current residual pressure ΔpR matches, to within a specified tolerance, the reference pressure value determined without a coupled trailer vehicle.
However, the line volume VBC of the brake control line is determined as the line volume of a reference pressure value determined with a coupled trailer vehicle, if the current residual pressure ΔpR matches, to within a specified tolerance, the reference pressure value concerned.
Besides, the line volume VBC of the brake control line can be determined by an interpolation between two line volume values of two reference pressure values determined when a trailer vehicle is coupled, if the current residual pressure ΔPR is between the two reference pressure values concerned.
After a longer interruption of the driving, the supply pressure in the supply lines of a tractor vehicle, a trailer vehicle, and in the storage containers connected to them can fall due to leakage, so that when the operation of the tractor vehicle starts again, at first a relatively low supply pressure is available. Since the brake control line is vented from the supply line of the tractor vehicle on the input side by way of the trailer control valve, producing the target pressure when the supply pressure is low requires opening pulses of the inlet valve with larger pulse widths and/or more opening pulses of the inlet valve and/or more time. Likewise, when the supply pressure is low more pressure oscillations and/or pressure oscillations with a greater or smaller amplitude can be excited in the brake control line and after the delivery of a pressure pulse the residual pressure in the brake control line may be lower.
It is therefore advantageous if, in all the methods and method variants mentioned, the current trailer status of the tractor vehicle and/or the current line volume VBC of the brake control line are determined and, in addition, the current supply pressure pV in a supply line of the tractor vehicle is measured, and the comparison of the respective characteristic value Σ PWIV−Σ PWOV, nP, Δpz, nS, AS_m and the residual pressure ΔpR is compared with reference values or reference pressure values determined and stored beforehand for the corresponding supply pressure pV.
To increase the accuracy, it can also be provided that the current trailer status of the tractor vehicle and/or the current line volume VBC of the brake control line are determined by a combination of at least two of the method variants mentioned.
In accordance with another further development of the method the current trailer status of the tractor vehicle and/or the current line volume of the brake control line are determined automatically, i.e., without an actuation of the brake pedal by the driver, each time the operation of the tractor vehicle begins afresh, i.e., when the on-board electrical system is switched on by the driver, and/or after each time that the parking brake in the tractor vehicle is released by the driver.
Below, the invention is described in greater detail with reference to the example embodiments illustrated in the attached drawing, which shows:
In
The trailer control valve 2 comprises a pneumatically controlled relay valve 10, a pneumatically controlled breakaway valve 16, an inlet valve 12, an outlet valve 14 and a pneumatic pressure sensor 18. The inlet valve 12 and the outlet valve 14 are in each case in the form of 2/2-way magnetic switching valves, by means of which a pneumatic control pressure applied at a control inlet 24 of the relay valve 10 can be produced.
The switching magnets of the inlet valve 12 and the outlet valve 14 are connected to an associated electronic control unit 8 by electrical control lines 20, and the pressure sensor 18 is connected thereto by electric sensor lines 22.
The inlet valve 12 is closed when not energized and open when energized. The outlet valve 14 is open when not energized and closed when energized. A control pressure line 28, which leads from the outlet of the inlet valve 12 and from the inlet of the outlet valve 14 to a control inlet of the breakaway valve 16 and via a line branch 28a to the direct first control inlet 24 of the relay valve 10, can be connected by way of the inlet valve 12 to an internal supply pressure line 30 and by way of the outlet valve 14 to a venting line 32 that leads to a venting outlet p3. A supply pressure line 30 is connected to a supply pressure inlet p11 of the trailer control valve 2.
In the installed condition of the trailer control valve 2, an external supply pressure line of a pneumatic compressed-air supply unit of the tractor vehicle is connected to the supply pressure inlet p11, which when the drive motor of the tractor vehicle is running, carries a supply pressure of around 7.5×105 Pa. A line section 30a branching off from the supply pressure line 30 leads via the breakaway valve 16 and a line section 30b on the output side to a supply pressure outlet p21 of the trailer control valve 2. To this supply pressure outlet p21 is connected, via an external supply pressure line 34, a “Supply” coupling head (red) 4. When a trailer vehicle is coupled, to the “Supply” coupling head 4 on the tractor vehicle side there is connected a supply pressure line 34′ of the trailer vehicle via a “Supply” coupling head 4′ on the trailer side, which leads to a trailer brake valve and at least one storage container of the trailer.
A supply pressure inlet of the relay valve 10 is connected to the supply pressure line 30 by way of the branched line section 30a and the line section 30b on the outlet side. A venting outlet of the relay valve 10 is connected by way of a connecting line 32a to the venting line 32 that leads to the venting outlet p3. A brake control outlet of the relay valve 10 leads via a brake control line 36 on the outlet side to a brake control outlet p22 of the trailer control valve 2.
To the brake control outlet p22 is connected a “Brake” coupling head (yellow) 6 via an external brake control line 42. When a trailer vehicle is coupled, a brake control line 42′ of the trailer is connected to the “Brake” coupling head 6 on the tractor vehicle side by way of a “Brake” coupling head 6′ on the trailer side, which leads to the trailer brake valve (not shown) of the trailer vehicle and, if present, to a “Brake” coupling head positioned at the rear of the trailer vehicle for connecting the brake control line of a second trailer vehicle.
The pressure sensor 18 is connected by way of a sensor pressure line 38 to the brake control line 36 on the outlet side. A further control pressure line 40 is arranged between an inverted control pressure inlet p43 of the trailer control valve 2 and an inverted second control inlet 26 of the relay valve 10.
During a braking process, a target pressure pZ is determined in the electronic control unit 8 from a braking value communicated by a brake control unit in the tractor vehicle, which is then produced in the trailer control valve 2 by pulse-like opening and closing of the inlet valve 12 and the outlet valve 14 by means of the relay valve 10 in the brake control line 42, 42′. When a trailer vehicle is coupled, the corresponding brake control pressure (pBC=pZ) in the trailer brake valve of the trailer vehicle leads to the production of a corresponding brake pressure for actuating the wheel-brake cylinders of the trailer vehicle.
To be able to control a braking process of a vehicle combination in an optimum manner, knowledge about the trailer status is useful, namely whether at least one trailer vehicle is coupled to the tractor vehicle or whether no trailer vehicle is coupled. In addition, for that purpose, when a trailer vehicle is coupled it is necessary to know the line volume of the brake control line 42, 42′ that runs from brake control outlet 22 of the trailer control valve 2 in the tractor vehicle to the brake control inlet of the trailer control valve in the trailer vehicle, in order to be able to build up the specified brake control pressure (pBC=pZ) quickly in the brake control line 42, 42′ for a largely delay-free actuation of the wheel brakes of the trailer vehicle. Thus, for example, in a method for controlling the brakes of a vehicle combination as described in DE 10 2020 106 448 A1, for this purpose it is provided that at the beginning of a braking process a pressure pulse higher than the brake control pressure to be produced is delivered into the brake control line, the level and/or the duration of which pulse depend(s) on the line volume of the brake control line determined.
In the above method it is generally provided that, preferably automatically, after every fresh operation of the tractor vehicle and/or after each releasing of the parking brake in the tractor vehicle, a target pressure pZ to be produced in the brake control line 42, 42′ is determined and specified, and that the target pressure pZ is produced in the brake control line 42, 42′ by pulse-like opening of the inlet valve 12 and/or the outlet valve 14, and that the brake control pressure pBC in the brake control line 42, 42′ is detected by sensor means during the pressure build-up, and that from the variation of the brake control pressure and/or from the switching states of the inlet valve 12 and/or the outlet valve 14, until the target pressure pZ has been reached a characteristic value is determined for the trailer status of the tractor vehicle and/or for the line volume VBC of the brake control line 42, 42′, and that this characteristic value is compared with at least one reference value determined beforehand as a function of the trailer status of the tractor vehicle and/or the line volume VBC of the brake control line 42, 42′ and stored in a data memory of the control unit 8, and that depending on the result of the comparison the trailer status of the tractor vehicle and/or the line volume VBC of the brake control line 42, 42′ is/are determined.
A first method variant is illustrated in the diagrams of
To determine a characteristic value, the pulse widths PWIV and PWOV of the inlet valve 12 and the outlet valve 14, shown in
A shown by
A second method variant is illustrated in
To determine a characteristic value, the opening pulses PIV_1 to PIV_11 of the inlet valve 12 required until the target pressure pZ is reached are summed to form an opening-pulse number nP as a reference value. Thereafter, by a comparison of the current opening-pulse number with opening-pulse number values determined beforehand for various line volumes VBC of the brake control line and stored as reference values, the current trailer status of the tractor vehicle and the current line volume VBC of the brake control line 42, 42′ are determined.
From a comparison of
The line volume VBC of the brake control line is determined as the line volume of the brake control line 42 that extends as far as the “Brake” coupling head 6, if the current opening-pulse number nP matches, to within a specified tolerance, the reference value determined when no trailer vehicle is coupled. In contrast, the line volume VBC of the brake control line is determined as the line volume of a reference value determined when a trailer vehicle is coupled, if the current opening pulse number nP matches, to within a specified tolerance, the reference value determined when a trailer vehicle is coupled, or by an interpolation between two line volumes of two reference values determined when a trailer vehicle is coupled, if the current opening-pulse number nP is between the two reference values concerned.
A fourth method variant is illustrated in the diagrams of
To determine a characteristic value, according to the two
By comparing the two
The line volume VBC of the brake control line is determined as the line volume of the brake control line 42 that extends s far as the “Brake” coupling head 6 when the current pressure build-up time ΔtZ matches, to within a specified tolerance, the reference value determined when no trailer vehicle is coupled. In contrast, the line volume VBC of the brake control line is determined as the line volume when a trailer vehicle is coupled if the current pressure build-up time ΔtZ matches, to within a specified tolerance, the reference value concerned, or is determined by an interpolation between two line volumes from two reference values determined when a trailer vehicle is coupled, if the current pressure build-up time ΔtZ is between the two reference values concerned.
Below, with the diagrams of
The pressure variations shown in
After a prolonged driving interruption, the supply pressure pV in the supply lines and the storage containers of a tractor vehicle and/or a trailer vehicle connected to them can fall due to leakage, so that when the traction vehicle begins operating again at first a relatively low supply pressure pV is available, owing to which the venting of the brake control line 42, 42′ is delayed.
To determine a characteristic value suitable for determining the volume of the brake control line connected, and with which it can be established whether a trailer vehicle is pneumatically connected to the tractor vehicle, this method variant provides that the number and/or the average amplitude of pressure oscillations of the brake control pressure pBC until the target pressure pZ has been reached is detected as a number of oscillations nS and/or an average oscillation amplitude AS_m that forms the characteristic value.
By comparing the current number of oscillations nS and/or the current oscillation amplitude AS_m with oscillation number values and/or oscillation amplitude values determined beforehand and stored for various line volumes of the brake control line as reference values, the current trailer status of the tractor vehicle and/or the current line volume VBC of the brake control line 42, 42′ are determined.
The trailer status as regards an uncoupled trailer vehicle is recognized if the current number of oscillations nS and/or the current average oscillation amplitude AS_m matches, to within a specified tolerance, a reference value determined when no trailer vehicle is coupled. The trailer status as regards a coupled trailer vehicle is recognized if the current oscillation number nS and/or the current oscillation amplitude AS_m is larger than the reference value determined when no trailer vehicle is coupled.
The line volume VBC of the brake control line is determined as the line volume of the brake control line 42 extending as far as the “Brake” coupling head 6, when the current number of oscillations nS and/or the current average oscillation amplitude AS_m match, to within a specified tolerance, a reference value determined when no trailer vehicle is coupled. In contrast, the line volume VBC of the brake control line is determined as the line volume from a reference value determined when a trailer vehicle is coupled if, to within a specified tolerance, the current oscillation number nS and/or the current average oscillation amplitude AS_m match the reference value concerned, or is determined by interpolation between two line volumes from two reference values determined when the current oscillation number nS and/or the current average oscillation amplitude AS_m is between the two reference values concerned.
From the curve shapes of the brake control pressure pBC in the diagrams of
The diagram of
This method variant provides that a pneumatic pulse to be produced in the brake control line 42, 42′ with a fixed opening duration ΔtIV of the inlet valve 12 is specified, and that the pressure pulse is produced in the brake control line 42, 42′ by a pulse-like opening of the inlet valve 12, and that the brake control pressure pBC present in the brake control line 42, 42′ after a specified time interval ΔtP is measured by sensor means as a residual pressure ΔpR, and that the residual pressure ΔPR is compared with a reference value determined beforehand as a function of the trailer status of the tractor vehicle and/or of the line volume of the brake control en 42 and stored in a data memory of the control unit 8, and that depending on the result of the comparison the trailer status of the tractor vehicle and/or the line volume VBC of the brake control line 42, 42′ is/are determined.
The trailer status when no trailer vehicle is coupled is recognized if the current residual pressure ΔpR, to within a specified tolerance, matches a reference pressure value determined when no trailer vehicle is coupled, and the trailer status when a trailer vehicle is coupled is recognized if the current residual pressure ΔpR is lower than the reference pressure value determined when no trailer vehicle is coupled.
The line volume VBC of the brake control line 42, 42′ is determined as the line volume of the brake control line 42 that extends as far as the “Brake” coupling head 6 when the current residual pressure ΔpR, to within a specified tolerance, matches the reference pressure value determined when no trailer vehicle is coupled. In contrast, the line volume VBC of the brake control line 42, 42′ is determined as the line volume of a reference pressure value when a trailer vehicle is coupled, if the current residual pressure ΔpR, to within a specified tolerance, matches the reference pressure value concerned, or is determined by an interpolation between two line volumes of two reference pressure values determined when a trailer vehicle is coupled if the current residual pressure ΔpR is between the two reference pressure values concerned.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2022 213 834.1 | Dec 2022 | DE | national |
