DE2122641C2 - Control valve for regulating brake pressure - has several cylinder surfaces and solenoid valves to provide fine control and prevent wheel lock - Google Patents

Abstract

The control valve (2) contains a piston (15) with, typically, two different surfaces (16,17). The corresponding cylinder space (18,19) are connected to electromagnetic valves (13,14) which are regulated by the electronic braking condition sensing equipment (8,9,10). The connections (22-30) in the control valve cylinder block between the cylinder spaces and the magnet valves are matched in cross sectional area. One magnet valve (13) acts as inlet and outlet, the other (14) as controlled outlet only. When the brake pedal (1) is depressed the piston (15) is forced down and the connection to the brake cylinder (3) made. If the sensor reacts to a condition of incipient wheel lock, the magnet valves are energised, either one or both, depending upon severity, then open. The path between the cylinder (18,19) and atmosphere is opened, the piston (15) rises and relieves the pressure on the brake cylinder. PS.

Description

The invention relates to a control valve for a blocking-protected, pressure-sensitive vehicle brake, which is arranged between a supply line and a brake line, at least one solenoid valve each for controlling the inlet and outlet and has several throttles, from an electronic, the Keeping the cadre monitoring output switches Receives signals and in each of the signals different according to the size of the blockicrgcfahr predetermined gradient for the reduction or build-up of the

Brake pressure is assigned.

Such a control valve is known from DE-AS il 66 012. The control valve consists of three individually operable solenoid valves, one solenoid valve for controlling the inlet and outlet is formed, while the other two Mapnetventile each have a throttled or an unthrottled supply or allow the pressure medium to flow away. This control valve is one such

to through-steering type. A pressure boost is not provided. In the case of a control valve, is the applied pressure is always the same as the applied pressure; with throttled flow only a temporal influence for the pressure build-up of the controlled pressure takes place.

In DE-PS 16 30 544 a compressed air control valve for vehicle brake systems is proposed in which a control piston is used which only has an effective area of the same size on the input and output sides possesses, so that the controlled and the controlled pressure are the same, so one Translation of I: 1 is available. It is true that this control valve can also be unthrottled or throttled on the input side be acted upon, so that the controlled pressure and accordingly also the controlled pressure are divided into two different speeds. There is a separate one for controlling the outlet Magi.etvcntil provided. Since this outlet can only be either open or closed, results

JO is only a gradient of the pressure reduction, so only one Possibility of reducing the pressure over time.

The invention is based on the problem of the speed of pressure reduction and / or pressure build-up to vary to a greater extent, so the possibility to create to be able to realize the pressure reduction and / or the pressure build-up at different speeds.

According to the invention, this is achieved in that the control valve has a plurality of piston surfaces Control piston having, each piston surface a

<tn solenoid valve is assigned. the one and / or Having outlet func- tion, and that between each Solenoid valve and the associated piston surface provided Lines are matched to one another in their cross-sections. This control valve is used in

·; ■> Connection with an electronic, the Drchbehavior the evaluation circuit that monitors the wheels and emits a corresponding number of different signals that Possibility created to enlarge the majority of the Slialtungs- and control options. That’s a

ίο better adaptation of the brake pressure to the different Frictional connection between bike and road possible. By arranging the several Piston surfaces on the control piston on one side and in connection with the associated magnetic valve

T> len can also or also be reductions Gear ratios between the respectively entered and the respectively modulated pressure on the control valve achieve. The adaptation of the cross-sections of the lines provided and their mutual coordination is necessary

w) required to achieve the desired effects to let the right time come. For example, when using a two delay and an electronic evaluation circuit emitting an acceleration signal in connection with

* '· One having two piston surfaces on the drive side Stepped pistons possible, all piston surfaces functionally via a solenoid valve for the inlet and a large available cross-section

to ventilate quickly, but to vent the individual piston surfaces at different speeds in order to To vary the rate of depressurization.

If only one solenoid valve is provided for the inlet, which with all piston surfaces in There is an operative connection, is a very simple and thus inexpensive implementation option Invention, which is sufficient in most cases, since the most difficult problems are in the adaptation of the Brake pressure is not present when the pressure is built up, but when the pressure is reduced.

In a special embodiment, in one line between the solenoid valve for the inlet and the outlet and the associated piston area, a throttle and a check valve are connected in parallel be. It is of course also possible to use the lines described in one or more of the lines To make arrangement.

For the purpose of rapid venting of the individual piston surfaces, an actuating valve can be used in the respective one A check valve can be provided to the solenoid valve for the control line leading to the outlet.

In an embodiment of the control valve equipped with particular advantage, are effective several solenoid valves for the variation of the pressure build-up and several solenoid valves for the variation of the Depressurization provided, the number of solenoid valves for the inlet and the number of Solenoid valves for the outlet is less than or equal to the number of piston surfaces.

Several or all of the solenoid valves for the outlet can have a common outlet line be connected in series. With this arrangement, the following piston surfaces can be vented can be prevented if the first piston surface is not ü should graze deflated.

The invention is further developed with the aid of a number of structural designs and possibilities of sounding clarifies, namely shows

Fig. I a first embodiment of the control valve with two effective piston surfaces.

Fig. 2 is a pressure-speed diagram of a control with the control valve according to Fig. I.

FIG. J another Ausrührungsbeispiel of the control valve with a stepped piston, of the three Kolbcnfliichcn having 4 ^r> and

F i g. 4 the associated pressure speed diagranim.

The two embodiments shown in FIGS. 1 and 3 are constructed similarly. You let through the modification of the signals of the electronic evaluation circuit and through the increase of the effective piston areas. The in F i g. I system shown essentially has an actuating valve 1. a control valve 2 and one or more brake cylinders 3. The invention is based on a with Compressed air working system shown. This compressed air is supplied by a Drtickluftbcschaffungseinrichtung, not shown and is available via a line 4 at the actuation valve 1. The line 4 hai wi Connection via a supply line 5 to the control valve 2. A control line leads from the ventilation valve I 6 to the control valve 2. The brake cylinder or cylinders 3 are connected to the control valve 2 via a line 7.

An electronic Auswcrteschaltung has a h ^r> sensor 8 and a measuring and Vcrarbcitungscinrichtiing IO, said sensor 8, and measuring and VerarbciUingscinrichtung 10 are connected via an electric line. 9 An electrical line 11 leads from the electronic measuring and processing device 10 to a solenoid valve 13 for inlet and outlet, which is provided on the control valve 2. Similarly, an electrical line 12 leads to the solenoid valve 14 for the outlet. The control valve 2 has a control piston 15 which is divided into two effective piston surfaces 16 and 17. Control chambers 18 and 19 are formed above the piston surfaces 16 and 17. The solenoid valve 13 for inlet and outlet is designed as an inlet valve for both control chambers 18 and 19. For this purpose the control line 6 is brought up to the inlet 20 of the solenoid valve 13. The armature 21 is shown in the position in which the solenoid valve 13 is de-energized. Thus, the control line 6 is connected to the control chamber 18 via the inlet 20, a bore 22 and a throttle 23, while there is an additional connection to the control chamber 19 via lines 24 and 25 and the check valve 26. A line 27 which is parallel to the bore 22 and is provided with a check valve 28 leads from the line 24. likewise to the control room 18. The solenoid valve 13 has an outlet seat 29 and a line 30 leading into the atmosphere, which in hydraulically operating systems is connected in a corresponding manner to a return system.

The solenoid valve 14 functions only as an exhaust solenoid valve. It is with its inlet 31 about one Check valve 32 connected to control line 6. The solenoid valve 14 has a line 33 with the control room 19 connection. In addition, its outlet seat 34 is connected to line 24.

In the control valve 2, a double valve body 35 is provided, which is hollow. Via an outlet 36, which is normally open, is a fault chamber 37 and the brake cylinder 3 is connected to the atmosphere via the line 7. Inlet 38 is normally closed as the double valve body 35 is supported on a spring 39.

The function of the brake system with control valve 2 is as follows:

When actuating the actuation valve 1 sirömi Compressed air via the control line 6 both to the solenoid valve 13 for inlet and outlet as well as to the Check valve 32, which is connected upstream of the solenoid valve 14 for outlet. Since at this point the two solenoid valves 13 and 14 are not energized, the armatures 21 and 40 are in the illustrated Location. Compressed air flows past the armature 21 into the bore 22 and on the one hand via the throttle 23 to the filter chamber 18 and parallel to this via the check valve 28 in the line 27 also to the control chamber 18 and additionally Via the lines 24 and 25, the non-return valve 26 to the control chamber 19. In addition, compressed air arrives via the line 33 into the solenoid valve 14. The design of the throttle 23, the choice of the spring force, with which the check valves 28 and 26 are pressed and by the design of the cross sections of the Lines becomes a very specific temporal course of the pressure build-up in the control rooms 18 and 19 achieved. This pressure build-up causes the control piston 15 to move in the direction of the double valve body 35 shifted so that the outlet 36 is closed and the Inlet 38 is opened. As a result, supply air passes through the line 5, the open inlet 38 into the Combustion chamber 37 and from there via line 7 to the brake cylinders 3. The position of the Sieuerkolbens 15 will have an impact. so that an equilibrium of forces

between the pressures in the control chambers 18 and 19 and in the brake chamber 37 is achieved. The ones in the Supply air reaching brake cylinder 3 is proportionally controlled. In the final position is both the Outlet 36 and inlet 38 are closed.

Each pressure increase or pressure decrease in control line 6 causes an analog pressure increase or pressure reduction in line 7 and thus in brake cylinder 3.

If the braking force generated by the braking pressure has exceeded the braking force that can be transmitted between the tire and the road surface due to the load conditions and the existing frictional connection, and the first rotational deceleration threshold is reached in the sensor 8 monitoring the wheel speed vR due to the rotational deceleration of the vehicle wheel, so that a first deceleration signal - b 1 through the electrical line 9 given to the electronic device 10 (Fig. 2-1), the solenoid valve 13 is excited via the electrical line 11, the inlet 20 is closed by the armature 21 and the outlet 29 is opened so that the control chamber 18 through hole 22, Throttle 23, outlet 29 and line 30 is vented.

Since the control chamber 19 remains ventilated by the blocking effect of the check valve 26 and the armature 40 of the second solenoid valve 14, which is pressed under pressure on the outlet seat 34, the pressure in the brake chamber 37 and the brake cylinder 3 is only reduced until the forces are equal again exists between the effective piston surface 17 and the control pressure acting on it and the control pressure remaining in the brake chamber 37 and the residual brake pressure remaining in the brake chamber 37 and acting on the underside of the control piston 15. The relatively flat pressure drop ρ in FIG. 2 is interrupted before the first delay signal - b \ - see point II - disappears and the pressure is kept approximately constant.

If the first deceleration signal - b \ ceases to exist due to re-acceleration of the vehicle wheel (Fig. 2 - III), the first solenoid valve 13) is de-energized and the control pressure is applied again to both effective piston surfaces 16 and 17, which results in a renewed pressure increase in the brake cylinder 3.

If the wheel deceleration vR increases by z. B. frictional connection change so strong that the first and second delay signal —fei; and -b2 come simultaneously (Fig. 2-IV), the two solenoid valves 13 and 14 are excited simultaneously via the electrical lines 11, 12 and the brake pressure ρ is rapidly reduced (Fig. 2- ρ 1).

If the second deceleration signal - b 2 is deleted by the re-acceleration of the vehicle wheel (Fig. 2 - V) and the solenoid valve 14 is de-energized, the brake pressure in the brake cylinder 3 may remain proportional to the residual control pressure in the control chamber 19 until an acceleration signal + b passes the solenoid valve 13 also de-energizes (Fig. 2 - VI) and the brake pressure is increased again.

The relationship between the first and second delay signal - b \ and -62 is designed so that after the first delay signal - b 1 is no longer current, the first solenoid valve 13 is de-energized so that when the second delay signal -62 occurs, the second solenoid valve 14 after it has ceased to exist de-energized, but the first solenoid valve 13 remains energized and only becomes de-energized when either an acceleration signal + b comes or a safety time of approx. 100 ms that begins with the energization of the second solenoid valve has expired. For this purpose, the measuring and processing device 10 is designed accordingly.

The brake system explained with reference to FIGS. 1 and 2 has - in terms of effect - a solenoid valve 13 for the inlet and two solenoid valves 13 and 14 for the outlet and two effective piston surfaces 16 and 17. As in FIG. 2 shows the speed

to of the brake pressure increase does not vary. The timing of the increase in brake pressure is determined by the design of the system. It is of course possible, for example, to design the bore 22 and / or the throttle 23 accordingly or to select it to be adjustable or adjustable so that the time course of the brake pressure increase within a system can be matched or adjusted to the vehicle in question. The two solenoid valves for the outlet make it possible to lower the brake pressure either or as a function of a circuit at two different speeds. These two speeds or pressure curves are within the pressure curve in FIG. 2 denoted by ρ and ρ 1. In Fig. 2, the vehicle speed vF, the associated wheel speed vR and the pressure curve ρ are given as the abscissa over the time t. In detail, the points given have the following meaning:

l. The first delay signal -b \ occurs

II. Without loss of the first deceleration signal - b 1, a braking final position occurs

III. The first delay signal —b \ disappears

IV. The first and second delay signals - Λ 1 and - b 2 occur approximately simultaneously

V. Both delay signals -b \ and -b2 drop out at about the same time

VI. An acceleration signal + b occurs

The based on the F i g. 3 and 4 shown anti-lock vehicle brake with the control valve 2 is basically constructed like the previously described system. For identical or functionally identical parts identical reference symbols are therefore used.

In addition to the two solenoid valves 13 and 14, two further solenoid valves 41 and 42 are provided, whose inlets 43 and 44 are connected to the control line 6. The solenoid valve 41 exercises the Function of an inlet solenoid valve, while the solenoid valve 42 serves as an outlet solenoid valve. That Solenoid valve 42 has an outlet 47, which via a line 48 into the atmosphere or at hydraulic operated systems leads to a return device.

The control piston 15 has three effective piston surfaces 16, 17 and 49. Above the piston surface 49 there is a control chamber 50 which is connected to the solenoid valve 41 via a bore 51. Lines 52, 53, 54 and 55 lead from the solenoid valve 42 to the control chambers 19, 18 and 50. Check valves 56, 57 and 58 are provided in lines 53, 54 and 55.

The solenoid valve 13 has at its inlet 20 a

A! Aßdüse59.

The solenoid valves 41 and 42 are connected to the electronic measuring and processing device 10 via the electrical lines 60 and 61.

This vehicle brake works as follows:

When braking, compressed air comes from the actuation valve 1 through the control line 6 to the inlet nozzle 59 on the solenoid valve 13, through the bore 22 and the throttle 23 into the safety space 18 of the effective piston surface 16 and at the same time through the lines 24, 27, the check valve 28 into the control room 18. Simultaneously the control chamber 19 of a further piston surface 17 becomes through the line 25 via the check valve 26 ventilated.

Via the control line 6, compressed air reaches the inlet 43 on the solenoid valve 41 and the inlet 44 on the solenoid valve 42, through the bore 51 into the control chamber 50 of the piston surface 49 and through the lines 52, 53, 54 and 55 to the check valves 56, 57 and 58. ι ·>

The control piston 15 formed from the piston surfaces 49, 16 and 17 moves downwards, closes the Outlet 36 and opens the inlet 38, so that proportional to the control pressure in the control line 6 compressed air through Line 7 reaches the brake cylinder 3. At the same time 2 »the brake chamber 37 is ventilated so that at When the forces acting on the control piston 15 are equal, the inlet 38 closes and the outlet 36 closes remains closed. This represents a brcms completion representation.

Each pressure increase or pressure decrease in the control line 6 causes an analog pressure increase or pressure reduction in line 7 and thus in brake cylinder 3.

If the braking force generated by the braking pressure has exceeded the braking force that can be transmitted between the tire and the road due to the load conditions and the existing frictional connection and the first rotation deceleration threshold is detected by the sensor 8 monitoring the wheel speed, a first deceleration signal - 61 the electrical line 9 is given to the electronic measuring and processing device 10 (FIG. 4-1) and the solenoid valves 13 and 41 are excited via the lines II and 60, the inlet 20 is closed by the armature 21 and the inlet 43 by the armature 45 and at the same time the outlet 29 is opened so that the control chamber 18 is vented via the throttle 23, bore 22, outlet 29 and line 30. The pressure in the brake chamber 37 and thus in the brake cylinder 3 is reduced until the forces on the control piston 15 are equal again, with a residual brake pressure acting on the underside of the piston (FIGS. 4-11) remaining.

If the rotational deceleration of the wheel falls below the response threshold of the first deceleration signal due to the decrease in pressure, the solenoid valves 13, 41 are de-energized and the control pressure is applied again to the piston surfaces 16 and 49, so that a renewed pressure increase takes place. This case is shown in FIG. 4 not shown.

If, on the other hand, the rotational deceleration of the wheel continues to increase despite the pressure drop and the second rotational deceleration threshold is reached at the sensor 8, a further, higher-value deceleration signal - b 2 is passed through the electrical line 9 to the electronic measuring and processing device 10. As a result, the solenoid valve 14 is also energized (Fig. 4-III), whereby the control chamber 19 through the line 33 and via the throttle 62, the opening cross-section of which is larger than that of the throttle 23, the open outlet 34, lines 24, 2Z the open outlet 29 and the line 30 is vented and the pressure in the brake chamber 37 and thus in the brake cylinder 3 to the extent - but faster this time - is reduced until the forces between the top and bottom of the control piston 15 are equal again (F i g . 3-IV). At this point in time, the second delay signal - Z) 2 has not yet ceased to exist.

If the rotational deceleration of the wheel falls below the response threshold of the second deceleration signal -62 due to the pressure decrease, the solenoid valve 14 is de-energized and the armature 40 closes the outlet 34 again, so that any residual pressure that may still be present in the control chamber 19 is maintained. Is also the rotational deceleration threshold of the first delay signal - 61 below, the solenoid valves 13,41 remain energized until an acceleration signal + 6 occurs, but no longer than for a holding time of about 100 ms. This case is shown in FIG. 4 not shown.

If, on the other hand, the rotational delay of the wheel is reduced by z. If, for example, a change in frictional connection continues and reaches the third rotation delay threshold at sensor 8, another higher-value delay signal - 6 3 is given through the electrical line to the electronic measuring and processing device 10. The solenoid valve 42 is energized, the armature 46 closes the inlet 44 and opens the outlet 47 (FIG. 4 - V), whereby the control chamber 50 is also vented and vented via the check valve 58, lines 55, 52, the open outlet 47 and line 48 the pressure in the control chamber 37 and thus in the brake cylinder 3 is lowered (FIG. 4 - ρ 4).

After the third delay signal - 63 (FIG. 4 - VI) has ceased to exist, the solenoid valve 42 is de-energized and an im Control chamber 50 any residual pressure that may still be present is retained.

If the acceleration threshold of the first acceleration signal + 61 (FIG. 4-VI) is reached by the re-acceleration of the wheel, the solenoid valves 13, 14 and, if not already de-energized, also the solenoid valve 42 are de-energized and the pressure build-up is slowed down (FIG. 4 -ρ 5) takes place through the inlet nozzle 59 on the solenoid valve 13 into the control chambers 18 and 19 and analogously to this in the brake chamber 37. Line 7 and brake cylinder 3.

If the rotational acceleration of the wheel increases further and the second rotational acceleration threshold is reached, so that the second acceleration signal +62 occurs, the solenoid valve 41 is also de-energized and the control chamber 50 is also ventilated (Fig. 4- / 36). whereby the brake pressure in the brake cylinder 3 is increased more quickly.

If the turning delay of the wheel is so sudden that the individual turning delay thresholds are briefly passed through to the highest response value (Fig. 4-IX), all solenoid valves 13, 14, 41, 42 are energized and the control rooms 18, 19 and 50 are energized by the solenoid valve 42 Quickly vented via the check valves 56, 57 and 58 (Fig.4-ρ7) and the pressure in the brake cylinder 3 is reduced analogously until the rotation deceleration threshold of the third deceleration signal -63 is undershot (Fig.4 -X) and the solenoid valve 42 is de-energized.

If the rotational acceleration of the wheel occurs so suddenly that the second higher-value acceleration signal + 62 occurs immediately (FIG. 4 -XI), the solenoid valves 13, 41 are de-energized and a rapid pressure build-up is enabled (FIG. 4- ρ 8).

Since it can now happen that the rotational acceleration the second spin threshold does not

reached, whereby the solenoid valve 41 remain energized became the electronic measuring and processing device 10 designed so that the solenoid valve 13 with the beginning of the first acceleration signal + 6 I is de-energized when the second or third delay signal! was previously achieved and that Solenoid valve 41 is de-energized at the end of the first acceleration signal + oil.

Furthermore, the electronic measuring and processing device 10 was designed in such a way that each acceleration signal + 6 can terminate each deceleration signal -b.

As can be seen, it is possible to equip the control piston with several effective piston surfaces and to provide different solenoid valves for inlet and outlet, so that the time course of pressure build-up and pressure reduction can be influenced. There are only two exemplary possibilities on the basis of FIG. 1-4 explained; these examples can be multiplied at will. However, with an increasing number of effective piston surfaces and an increasing number of Magnelventi-Ie, the structural effort also increases. For this, however, the pressure curve of the brake pressure in the wheel brake cylinders is better and better adapted to the time curve of the wheel speed vR. This adaptation is achieved through the different gradients of the pressure build-up (pi, ρ 5, ρ 6, ρ8) and the pressure decrease (ρ 2, ρ 3, ρ 4, ρ 7). The anti-skid device is operated in such a way that a pressure increase or pressure reduction adapted to the frictional connection conditions is carried out, so that the bumps, which are particularly disadvantageous, are completely avoided or at least greatly limited in number.

The curve of the brake pressure ρ and the curve of the vehicle speed vF and the wheel speed vR over time are shown in I "i g , where the straight sections ρ 1, ρ 6 and ρ 8 run parallel to each other and allow a rapid pressure increase, while the pressure increase ρ5 is flatter, so that the wheel has a longer opportunity to brake the vehicle under optimal friction conditions Pressure reduction ρ 2, ρ 3, ρ 4 and ρ 7 are provided, with the straight sections ρ 4 and ρ 7 again being parallel and representing the fastest possible way of reducing the pressure Druckaufbaugcsehwindigkeilcn, because a finer gradation of the pressure reduction allows better adaptation and greater security against n reaching the blocking limit. The in F i g. 4 marked points represent the following truck situations:

I. The first Vcr /. Delay signal - 6 1 occurs

II. A brake closure position is achieved

III. The second delay signal -62 occurs in addition

IV. A further breach of the problem is reached

V. The third delay signal -63 also occurs

VI. Another brake closure is achieved

VII. The first acceleration sign + b 1 up

VIII. In addition, there is the wide acknowledgment signal +62 on

IX. All delay signals -6 1, -62 and -6 J occur almost simultaneously

X. A braking final position is reached

XI. Both acceleration signals +61 and +62 occur almost simultaneously.

For this purpose 2 sheets of drawings

Claims (6)

Patent claims: 1. Control valve for an anti-lock, pressure medium-actuated vehicle brake, which is arranged between a supply and a brake line, has at least one solenoid valve each for controlling the inlet and outlet and several throttles,. receives signals from an electronic evaluation circuit that monitors the rotational behavior of the wheels and in which each of the signals, which differ according to the magnitude of the risk of locking, is assigned a predetermined gradient for reducing or building up the brake pressure, characterized in that the control valve (2) has a plurality of piston surfaces (16 , 17, etc.) having control piston (15), each piston surface (16, 17) being assigned a solenoid valve (13, 14 , etc.), which has an inlet and / or outlet function, and that the between each solenoid valve (13 , 14 , etc.) and the associated piston surface (16, 17, etc.) provided lines (22 to 30) are matched in their cross-sections. 2. Control valve according to claim 1, characterized in that only one solenoid valve (13) for the Inlet is provided which is in operative connection with all piston surfaces (16, 17, etc.). 3. Control valve according to claim 1 or 2, characterized in that in one line (22) between the solenoid valve (13) for the inlet and the outlet and the associated piston surface (16) a throttle (23) and a check valve (28) are sounded in parallel. 4. Control valve according to one of claims I to 3, characterized in that for the purpose of faster Ventilation of the individual piston surfaces (16, 17, etc.) in the respective door leading from an actuating valve (1) to the solenoid valve (14) Stciicrlciliing (6) a check valve (32) is provided is. 5. Control valve according to claim 1, characterized in that effectively several solenoid valves (13, 41 , etc.) for the variation of Druckaiifbaus and several solenoid valves (13, 14, 42, etc.) are provided for the variation of the pressure reduction, the number of Solenoid valves for the inlet and the number of solenoid valves for the outlet is less than or equal to the number of piston surfaces. 6. Control valve according to claim 2 or 5, characterized in that several or all of the solenoid valves for the outlet (13,14 etc. or 13,14,42 etc.) are hinicreinandergcschaltel via a common outlet line (24 or 52).