DE3244481A1 - DELAY DETECTING MODULATOR VALVE FOR VEHICLE BRAKE SYSTEMS - Google Patents

Description

PATENT LAWYERS

WUESTHOFF-v. PECHMANN-

EUROPEAN PATENT TORNEYS

1A-56 752

OR.-1 NC. FRANZ TUESTHOFF

'WC. PHIL. FREOA TTUESTHOFF (1927-1956) DIPL.-INC. GERHARD PULS (19J2-I971) DIPL.-CHEM. DR. E. BARBER OF PECHMANN DR.-ING. DIETER BEHRENS DIPL.-ING .; DIPL.-TIRTSCH.-ING. RUPERT GOETZ

D-8000 MUNICH SCHWEIGERSTRASSE 2 phone : (089) 66 20 ji

TELEGRAM: PROTECT PATENT

telex: j 24 070

December I, 1982

Patent application

Applicant:

Lucas Industries public limited company

Great King Street

Birmingham 19, West Midlands, England

Title:

Modulator valve for vehicle braking systems that detects deceleration

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DtPL.-ING. GERHARD PUlS (19J2-I971)

EUROPEAN PATENT TORNEYS. ζ, _Dlri .. _c "". _D , _E. m, " _E n of" chwnn

PR.-ING. DIETER BEHRENS DIPL ₁ -ING ₁ ; DIPL.-WIRTSCH.-1NG. RUPERT GOETZ

1A-56 752 D-8000 MUNICH 90

SCHWEIGERSTRASSE 2

phone: (089) 6620 ji
telegram: protectpatent
Telex: 524070

Delay sensing modulator valve
for vehicle braking systems

The invention relates to deceleration detecting modulator valves for vehicle brake systems, with a housing with a
Inlet and an outlet opening for brake pressure, a control piston working in the housing, which establishes the relationship between
able to control the inlet and outlet pressures, and an im
Housing arranged delay sensor, which is able to actuate a delay valve when the housing is delayed beyond a delay threshold value, through whose actuation the control carried out by the control piston can be influenced.

Many proposals have been made for valves of this type. Usually the brake pressure inlet of such a valve is connected to a brake pressure source, which is also connected to
is connected to the front wheel brakes, and the brake pressure outlet is connected to the rear wheel brakes, the control piston being designed so that at an inlet pressure which exceeds a corresponding threshold value, the increase in the outlet pressure is reduced compared to the increase in the inlet pressure
w'will to the changes of the

/ 2

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Weight distribution when decelerating the vehicle bill to wear.

It is known that to modify the relationship or the Relationship between the inlet and outlet pressures, the delay valve can be interpreted in different ways. The delay valve is used to account for the fact that to create a certain delay a loaded vehicle requires a higher brake pressure than an unloaded vehicle. It is therefore has been proposed to adjust the threshold value of the inlet pressure by making it dependent on the closure of the delay valve to modify. This avoids the use of a mechanical transmission that occurs when the vehicle load is changed appeals to.

In one type of such modulator valve, the delay valve is designed to provide a volume of fluid when it closes is enclosed in an adjustment chamber which is delimited by an adjustment piston which controls the control piston biasing spring controls. Usually a control spring for the control piston acts between the two pistons, however such an arrangement results in a relatively great length and not completely satisfactory operationally Characteristic values of the modulator valve.

A measure is known from GB-PS 2010425A which is based on aims to create better characteristics, but has resulted in a multi-component device.

It is an object of the invention to provide a modulator valve of the type described at the outset that has small dimensions has, is relatively cheap to manufacture and has satisfactory operational characteristics.

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According to the invention in a modulator valve is the initially

Change the type of delay sensor described in a cage

ordered, slidable in a / inlet pressure exposed chamber and for contact with a first contact surface on the housing and with a second contact surface on the control piston, it is elastic is preloaded, the delay valve on the control piston has a valve seat that is used to interrupt the connection with the inlet opening through the delay sensor can be closed, the cage has a valve opening section which can be placed against the delay sensor and is designed in this way is that the valve seat is opened when the control piston and the cage are out of positional relationship with respect to one another move out, in which the cage rests against the second contact surface, and the control piston has a first pressure-effective surface which is subjected to inlet pressure in order to exert a force on the control piston which is in the Cage acts in the opposite direction, and a second, oppositely acting pressure-effective surface, the outlet pressure exposed and larger than the first area, the area of the valve seat being included in the calculation of the first area is involved.

In the case of such a valve, after the valve seat has been closed by the delay sensor in the outlet / inlet pressure characteristic curve a considerable jump arise from the fact that the cage rests against the first contact surface, whereby the control piston is relieved of the spring force. The failure of the spring force on the control piston is an important factor which requires a substantial increase in inlet pressure before the outlet pressure rises again. Such a Jump is useful for offsetting the characteristic curve away from the theoretically ideal curve, which is otherwise from the following one Dosing section of the characteristic curve would be cut. This would lead to the rear wheels locking.

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With such a valve it is also possible to make the first and the second surface at least approximately the same, see above that it can be ensured that when the vehicle is loaded, a gain section of the characteristic curve that occurs when the vehicle is closed of the valve seat begins by the delay sensor and a slope corresponding to the ratio of the two areas has a slope of almost 45 °, which means that at low inlet pressures a large approximation of the theoretical Curve is possible.

The first contact surface is preferably formed by a step in the housing against which one end of the cage rests.

The valve opening portion of the cage is preferably from an annular, radially inwardly directed lip of the cage formed, which on the second contact surface on Control piston can be applied to determine the distance covered by the control piston and the cage together.

The resilient device for biasing the cage is preferred a compression spring which is supported on an end wall at the end of the cage opposite the control piston.

A direct sealing system can be provided between the delay sensor and the valve seat. Another possibility consists in interpreting a perforated end wall of the cage on the side facing the control piston so that they around their opening on the one hand together with the valve seat and on the other hand together with the delay sensor able to seal in order to bring about an indirect seal between the delay sensor and the valve seat.

In one embodiment for a two-circuit brake system, the control piston is made up of two normally adjacent one another Piston parts assembled, with a first piston part

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has the valve seat and at the end remote from the valve seat is exposed to the outlet pressure of a brake circuit and at its opposite end to the inlet pressure of this brake circuit, and a second piston part at its end remote from the first piston part is exposed to the unmodified master cylinder pressure in the other brake circuit. In the event of a fluid pressure failure
in the latter brake circuit, the first piston part is outside
Operation, so that the first-mentioned brake circuit supplied
Outlet pressure, compared to the inlet pressure is not reduced.

Embodiments of the invention are explained in more detail below with reference to schematic drawings. It shows:
V shows a longitudinal section through a modulator valve according to

of the invention, wherein the components are shown in the non-actuated state of the modulator valve,
FIG. 2 is a diagram to illustrate the mode of operation of the modulator valve according to FIG. 1,

Fig. 3 is an enlarged view of a relative to the embodiment according to Fig. 1 modified sealing arrangement,

4 shows a longitudinal section through a modulator valve according to
of the invention for a dual-circuit brake system, wherein
the components are shown in the non-actuated state of the modulator valve, and

5 is a diagram to illustrate the method of operation
of the modulator valve according to FIG. 4.

The modulator valve shown in Fig. 1 has a housing 1, in which a stepped bore 2 is composed of bore sections 3, 4 and 5 each of a smaller diameter. the Stepped bore 2 is closed at one end with a plug 6 which has an inlet opening 7 which is connected to a Master cylinder outlet is connectable. The stepped bore 2 with an outlet opening 8 is at its opposite end in connection with an actuator for

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Rear brakes can be connected. An externally stepped control piston 9 has a left piston section 10 of larger size Diameter which is displaceable in the bore section 5 and sealed against it by an O-ring seal 11, which is arranged in an outer, annular groove of the control piston 9, and a right piston portion 12 of smaller diameter, which is displaceable in a stationary ring 13 and arranged against it by an adjacent one O-ring 14 is sealed. The O-ring 14 is between the Wall of the bore portion 4 and the radially outer surface of the piston portion 12 pressed together radially. The ring 13 enables the machining of the stepped bore 2 from one end and at the same time forms the necessary, constriction complementary to piston section 12. Behind the ring 13 a vent opening 13 'leads to the outside.

In the control piston 9, an axial through hole is incorporated, which is normally a direct connection between the inlet opening 7 and the outlet opening 8. At the right end of the piston section 12 is a truncated cone shaped valve seat 15 formed which the bore 16 surrounds and to which a ball 17 acting as a delay sensor can be placed in a sealing manner. The 'ball 17 is in a tubular shape Cage 18 arranged.

The cage 18 is axially displaceable in the bore section 3 and in the direction of a step 19 in the housing 1 between the bore sections 3 and 4 is formed by one preloaded, in the example shown, formed by a coil spring compression spring 20 biased between the Stopper 6 and an end wall 21 formed in the example shown by a closure plate acts, which the ball Holds captive in the cage 18. The cage 18 has on his left end a radially inwardly directed, annular lip 22. This is on a contact surface 23 on a

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circular shoulder can be placed on the piston section 12 by reducing the outer diameter of an end section 24 was created. The end portion 24 is with considerable play in the. central opening formed by the lip 22 recorded. The length of the end section 24 is selected so that the ball 17 comes into contact with the cage 18 when the cage 18 is in contact of the contact surface 23 in a sealing manner against the valve seat 15 can without being hindered by the lip 22, and that only a small separating movement of the cage 18 and the control piston 9 in relation to each other is necessary before the lip 22 engages the ball 17 in order to remove it from the valve seat 15.

The cage 18 has at least one axial slot 25, the penetrates lip 22 and ensures that inlet pressure reaches the chamber in which O-ring 14 is located.

The operation of the modulator valve of FIG. 1 will now be described with reference to FIG. The continuously running curves A and B represent the theoretically ideal relationships between represents the rear and front wheel brake pressures for the driver-only vehicle and the fully loaded vehicle.

The actuation of the modulator valve when the vehicle is occupied only with the driver is considered first. In the first When the brakes are actuated, the components take those shown in FIG Positions. The housing 1 is installed in a vehicle so that the left end faces the front of the vehicle and a small angle is formed with the horizontal, so that the right end is lower than the left. Based on these In an inclined position, the ball 17 rests against the end wall 21 and has ample distance from the valve seat 15, so that initial increases in the inlet pressure through the bore 16 directly to the Outlet opening 8 are passed on and generate the curve section CD.

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324A481

56 752

According to FIG. 2, the curve section CD runs completely below the theoretical curve A. At low braking pressures, it is particularly important that the output pressure does not exceed the theoretical curve, because otherwise the rear wheels could lock. It is ensured that in point D lying immediately below curve A, the deceleration of the vehicle occupied only with the driver is just sufficient to cause the ball 17 in the cage 18 to roll to the left and to lie against the valve seat 15, the control piston 9 being held in the position shown in FIG. 1 due to the rightward force which is generated by the inlet pressure (equal to the outlet pressure) which acts on the opposite pressure-effective surfaces A _{1 of} the piston section 12 and A_ of the piston section 10. The area A ₁ corresponds to the bore of the ring 13, A_ the cross-sectional area of the bore section 5; because A "is greater than A ₁ , the excess force effective on the control piston 9 is directed to the right.

It is ensured that the fluid pressure excess force which acts on the control piston 9 and is directed to the right at point D the preload of the compression spring 20 is just the same State of the vehicle of the cage 18 at the point where the Ball 17 rolls from which stage 19 would have been moved.

If the inlet pressure is increased starting from point D when the vehicle is only occupied by the driver, this results from the Effect of the increasing inlet pressure on the area A, with the valve seat 15 closed, an increase to the left Fluid pressure force acting on the control piston 9, so that the control piston 9 moves to the left and by lifting of the game between the ball 17 and the lip 22 the ball 17 rests on lip 22. Because the cage 18 by its system is supported on the step 19 by the housing 1, results from the abutment of the ball 17 on the lip 22 a

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effective reduction of the area of the control piston 9 over which the inlet pressure acts. This area reduction is equal to the area A- which is enclosed by the line of contact of the ball 17 with the valve seat 15. Because the inside of the valve seat 15 as before via the bore 16 with the Outlet opening 8 is in communication, is also the area A_, on which the outlet pressure acts is effectively reduced so that the operationally effective area is A-A.

Furthermore, when the control piston 9 moves to the left, it moves out of the position shown in FIG. 1 relieved of the force of the compression spring 20, because this force by the application of the cage 18 to the step 19 completely from Housing 1 is added. This means that the inlet pressure must increase by an amount that compensates for the loss of spring force compensates.

The effective change in the area A _{3 of} the control piston 9 and the loss of the spring force mean that the inlet pressure must rise considerably, namely after point E, before the outlet pressure increases further.

At point E, the force generated by the inlet pressure acting on the control piston 9 to the right via an area A, -A is equal to the force generated by the outlet pressure acting on the control piston 9 to the left via the area A_-A is generated, so that with a further increase in the inlet pressure, the control piston 9 moves to the left and the ball 17 is lifted from the fixed lip 22 of the valve seat 15. When the control piston 9 moves back and forth, with the valve opening and closing, a metering effect then results which generates the curve section F according to FIG. 2, which has a gradient of (A ₁ -A ₃ ) Z ( A ₂ -A ₃ ) has.

BATH ORIGINAL

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Although the curve section F would eventually intersect the theoretical curve A, this only happens at high inlet pressures, where the front wheels would have locked anyway.

The operation of the modulator valve according to FIG Fig. 1 viewed with a fully loaded vehicle. In this vehicle condition the inlet pressure increases from C to G before the vehicle has decelerated enough to coast and to bring about the application of the ball 17 to the valve seat Ί5. It was ensured that the excess force directed to the right, from the to the right on the control piston 9 over an area A "-A. acting inlet pressure is generated, at point D equals the preload of the compression spring 20, so that the control piston 9 and the cage 18 when the inlet pressure increases from D to G by the increasing fluid pressure force on the control piston 9 with respect to the housing 1 to the right are moved and thereby increase the load in the compression spring "20 .

After the valve seat 15 has been closed at point G by the ball 17, a further increase in the inlet pressure acting on the area A, leads to a gradual adjustment of the control piston 9 together with the cage 18 to the left, so that the outlet pressure at a rate which is determined by the area ratio A ₁ ZA ₇ , increases since the valve seat 15 is closed. This creates the curve section GH. The invention enables this ratio to be relatively close to 1 in order to obtain a slope of a little under 45 ° so that a maximum gain of the point G is produced. At low inlet pressures there is therefore a close approximation of the course of the theoretical curve.

At point H, which is placed directly below the theoretical curve B, the cage 18 rests against the step 19 and almost simultaneously with this, a movement of the control

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piston 9 to the left to bring the lip 22 with the ball 17 in contact, the surface A, of the control piston 9 made ineffective. As in the case of an unladen vehicle, this results in a delay in the further increase in the outlet pressure as the inlet pressure increases, by the amount of the effective loss of the area A-. To be taken into account, and a relief of the control piston 9 from the spring force when the cage 18 rests against the step 19 in the housing 1. At point K, the _{force generated by the inlet pressure acting on the area A 1} -A ₁ and acting to the left on the control piston 9 is sufficient to overcome the right-directed force generated by the outlet pressure acting on the area A_-A_, see above that in this case, too, a metering begins, the relationship between outlet and inlet pressure being the same as for curve section F and generating curve section J, which is, in terms of effect, a continuation of the line representing curve section F.

The modulator valve shown in Fig.! 'Therefore generates the considerable shifts from D to E or from H to K in the characteristic curves to ensure that the actual Valve characteristics do not intersect the theoretical curves except at high inlet pressures and yet at low ones Pressures in the areas from C to D and C to H for the vehicle occupied or fully loaded with only the driver, the theoretical Follow curves pretty closely.

The end wall 21 has a group of openings 26 so that the ball 17 upon rapid actuation of the master cylinder due to sharp braking by fluid pressure forces on the valve seat 15 is pressed to move the point D towards lower pressures. The realization of this feature is -by the arrangement of the ball 17 in the direct fluid path between the inlet opening 7 and the outlet opening 8 simplified.

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The arrangement of all components in a single stepped bore 2 instead of in separate bores contributes to a reduction in the Manufacturing costs.

FIG. 3 shows a comparison with the embodiment according to FIG. 1 modified sealing arrangement with direct metal-to-metal contact between the ball 17 and the valve seat 15. In 1 and 3 corresponding components are denoted by the same reference numerals. In the embodiment according to 3 has the cage 18 on the piston section 12 facing Side one end wall 27 with a central hole 28 running on opposite sides of the end wall 27 from onto the end wall 27 glued-on elastic seat rings 29 and 30 is enclosed. The seat ring 29 can be attached to the valve seat 15 to create bevel on the piston section 12, to seal between the end wall 27 and the piston portion 12, and the ball 17 is able to contact the seat ring 30 in a sealing manner. When the inlet pressure rises for the first time the control piston 9 moves to the right and brings the bevel to rest on the seat ring 29. When the ball 17 then rolls forward and rests on the seat ring 30, will via the end wall 27 between the ball 17 and the inclined surface indirectly sealed at the end of the piston section 12. The radially inner edge of the bevel delimits the area A ^, which is made ineffective when the ball 17 rests on the seat ring 30 and the bevel on the seat ring 29.

The modulator valve shown in Fig. 4 is for a two-circuit brake system certainly. Components similar to those of the embodiments 1 and 3 correspond to the same reference numerals. In the embodiment shown the control piston is composed of two separable piston parts 31 and 32 which are in contact with one another, and it becomes a metering valve similar to the embodiment according to FIG. 3 used, with the exception that the seat ring 29 on

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the right end of the piston part. 32 is arranged. The bore 16 in the piston part 32 is via radial recesses or Grooves 34 in the left end face of the piston part 32 connected to an intermediate chamber 33 in the housing 1, with which the when Example shown transversely directed primary outlet opening 8 is in direct communication. ·.

The inlet port 7 is connected to an outlet 35 of a tandem master cylinder 36 connected, the second outlet 37 is connected to an opening 38 which is at the left end of the Piston part 31 opens into a chamber 39 which is directly connected to a secondary outlet opening 40. To the primary outlet port 8, an actuating device, not shown, for rear wheel brakes is connected, and the secondary outlet opening 40 is connected to an actuating device for front wheel brakes, also not shown.

The piston part 32 is an externally smooth piston, in which the right end is subjected to inlet pressure and the left end to primary outlet pressure, whereas the piston part 31 is stepped on the outside, with its larger left end secondary inlet pressure (equal to secondary outlet pressure) and its smaller right end to the pressure in the Intermediate chamber 33 is exposed. On the piston part 31, the area of its left end _{is denoted by A 1} and that of its right end is denoted by A ″. The cross-sectional area of the intermediate chamber 33 and that of the piston part 32 are denoted by A, the cross-sectional area of the seat ring 29 by A. However, these reference letters do not correspond to those used for the embodiment according to FIG.

It can be ensured that both brake circuits the characteristic curves of the modulator valve shown in FIG. 5 are the same as the characteristic curves of the embodiment according to FIG. 1, Corresponding curve sections are labeled identically. The pressure-effective area of the control piston 31,32,

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which is subjected to inlet pressure and acting in the opposite direction to cage 18 is A - A ,, because inlet pressure acts on the right end of piston member 32 and on the left end of piston member 31. The oppositely acting pressure-effective area of the control piston 31, 32 exposed to the outlet pressure is A ₃ -A ₃ . Thus, the slope of the characteristic curve section is GH (A ^ -A ₁ ) / (A_-A "), and that of the dosage sections F and J is (A ₃ -A, -A ₄ ) / (A_-A_-A.). If A, is smaller than A ₃ and the areas are selected appropriately, the same characteristic curves as in Fig. Can be obtained.

In the event of a pressure failure in the secondary brake circuit connected to the chamber 39, the left-facing area A ₁ for the inlet pressure is lost, so that the control piston 31, 32 is replaced by the primary inlet pressure which acts to the left on the area A ₃ at the right-hand end of the piston part 32, is held in the left end position in order to prevent the seat ring from sealing against the end wall 27 of the cage 18. Thus, even when the ball 17 rests on the seat ring 30, the intermediate chamber 33 remains in communication with the primary inlet opening 7 via the open valve seat formed by the seat ring 29, and maximum braking pressure is supplied to the rear wheels, as indicated by the dashed line L in FIG .

In a modified embodiment, not shown, of the modulator valve according to FIG. 4, the piston part 31 is a The piston is smooth on the outside and the piston part 32 is an externally stepped piston.

Claims (6)

DtPL.-INC. GERHARD PU LS (1952-1971) iÄ-56 752 D-8000 MUNICH 90 SCHWEIGERSTRASSE 2 TE LE PON: (089) 66 20 J I. TELEGRAM: PROTECTPATENT TELEX: 524070 Patent claims: (1.) Delay-sensing modulator valve for a vehicle brake system, with a housing with an inlet and an outlet opening for brake pressure, one working in the housing Control piston showing the relationship between inlet and outlet pressures able to control, and a delay sensor arranged in the housing, which over delays the housing a delay threshold is able to actuate a delay valve, through whose actuation the control piston control carried out can be influenced, characterized in that the delay sensor (17) is arranged in a cage (18), which is in an inlet pressure exposed chamber displaceable and to rest on a first contact surface (19) on the housing (1) and on a second The contact surface (23) on the control piston (9) is elastically pretensioned, and the delay valve on the control piston (9) has a valve seat (15) that has to interrupt the connection with the inlet opening (7) can be closed by the delay sensor (17) is, the cage (18) has a valve opening portion (22) which can be applied to the delay sensor (17) and so is designed so that the valve seat (15) is opened when the control piston (9) and the cage (18) with respect to one another move out of the positional relationship in which the cage (18) rests against the second contact surface (23), and that the control piston (9) has a first pressure-effective area (A ^) which is exposed to inlet pressure in order to exert a force on the control piston (9) which, in the opposite direction to the cage (18) / 2 • · * «· -"{'- 56 set direction acts, and a second, oppositely acting pressure-acting surface (A_), which is exposed to outlet pressure and greater than the first area (A.), the area (A-) of the valve seat (15) being included in the calculation of the first area (A,) is involved. 2. Valve according to claim 1, characterized in that the first contact surface of a step (19) in the Housing (1) is formed, to which one end of the cage (18) applies. 3. Valve according to claim 1 or 2, characterized in that the valve opening portion of the cage (18) is formed by an annular, radially inwardly directed lip (22) of the cage (18) which is attached to the second contact surface (23) on the control piston (9) can be applied to the control piston (9) and the cage (18) together determine the distance covered. 4. Valve according to one of claims 1 to 3, characterized ge indicates that the elastic device for biasing the cage (18) is a compression spring (20) which on one end wall (21) on the one opposite to the control piston (9) Supports the end of the cage (18). 5. Valve according to one of claims 1 to 4, characterized ge indicates that on the side facing the control piston (9) a perforated end wall (27) of the cage (18) is designed so that it is around its hole (28) on the one hand together with the valve seat (15) and on the other hand together able to seal with the delay sensor (17) to between the delay sensor (17) and the valve seat (15) to bring about an indirect seal. ι »ο ft β β - ϊ * - °°° * 56 6. Valve according to one of claims 1 to 5 for a two-circuit brake system, characterized in that that the control piston consists of two normally abutting one another Piston parts (31,32) is assembled, a first piston part (32) having the valve seat (15) and is designed so that it is removed from the valve seat (15) End exposed to the outlet pressure of a brake circuit and at its opposite end to the inlet pressure of this brake circuit is, and a second piston part (31) is designed so that it faces away from the first piston part (32) on its End of the unmodified master cylinder pressure in the other brake circuit is exposed. ■