DE2603380A1 - PNEUMATIC ACTUATING DEVICE FOR DISC BRAKES - Google Patents

Description

PATENT LAWYERS

HELMUT SCHROETER KLAUS LEHMANN

DIPL.-PHYS. DIPL.-INC.

Robert Howell Industries, Inc. cu-ho-10

Se / P - 26. I. 1976

Pneumatic actuator for disc brakes

That Essentials from Revelation

A heavy duty disc brake and a pneumatic actuator therefor are described. The pneumatic actuator may include a pair of annular pistons operatively connected for simultaneous movement, with means being provided for supplying pressurized air to the working surfaces of the pistons. However, it can also include a single spring loaded piston which is spring urged into the braking position, means being provided to direct compressed air to each side of the piston. The disk brake contains a plurality of relatively movable rotor and stator disks and preferably a closed cooling system with a circumferential fluid path.

Background and Summary of the Invention

The invention relates to the operation of heavy-duty disc brakes, e.g. truck disc brakes, by pneumatic devices. In the past it wasn't possible to use a purely pneumatic one Provide actuation for truck disc brakes, and because of the large forces required for a sufficient Braking must be applied and also because of the limitations on the size and location of such brake actuators, if you want to find a place in a vehicle. One

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However, purely pneumatic actuation has many advantages. Since no special liquid container is required, leakage is not nearly as important as in hydraulic systems and is much less likely to result in brake failure. Also are the maintenance requirements greatly reduced in the case of purely pneumatic actuating devices. In addition, these can be built more cheaply.

Despite the many advantages of purely pneumatic actuation, the actuators for heavy truck disc brakes were of the prior art is practically limited to the hydraulic mode of operation. Typical liquid operated devices for prior art disc brakes are disclosed in US Pat. No. 2,9 * 5 146, 3 036 869 and 3 108 658 are shown. Hydraulic actuation was necessary in such an environment because of the need to attach the disc brake unit to an axle Insufficient space for a pneumatic piston is large enough to allow heavy duty braking in a reasonable manner to operate, but at the same time to keep the assembly in such a size that it is arranged on a truck axle can be. U.S. Patent 3,680,666 suggests pneumatic actuation of a motor disc brake, but has one such actuation has not found practical application in heavy goods vehicles when the braking standards for trucks (in particular Flatbed trailers ^ as described in the Federal Regulations of Title 49, Chapter V, Part 57I _ Federal Motor Vehicle Safety Standards, Air Brake Systems Standard and Hydraulic Brake Systems in the Federal Register, Vol. 39, No. 97, May I7, 1974 and Vol. 37, No, 172, September 2, 1972j are laid down, should be fulfilled. According to the present invention, these standards can even be met with purely pneumatic actuation of the brakes.

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According to the present invention, a purely pneumatic actuating device is provided together with a heavy-duty Seheibenbrem sen unit. This actuating device preferably consists of a first annular piston which is arranged around a truck axle and has a supply of compressed air on one side, a vent opening in the cylinder behind the first Piston, a second annular piston which is in operative connection with the first, an air inlet on one side of this piston through a hollow component which establishes the operative connection between the first and the second annular piston, the second piston being designed to be operatively connected to be brought with discs of a heavy-duty disc brake. In this way, the effective area of a piston actuating device for the disc brake is greatly increased, while the size of the structural unit is only slightly increased, and this only in the longitudinal direction of the axis along which the arrangement of the brake is cheaper than in the width direction. While double pistons are known per se - see, for example, US Pat. No. 2,956,519 and 2,983,256, the combination of purely pneumatically actuated annular double pistons and a disc brake, or the advantages resulting therefrom, was not known from the prior art.

Another example of a purely pneumatic actuator consists of a single piston which is spring loaded in the closing direction and which can be opened as well as for effective braking with compressed air.

According to a preferred embodiment of the invention, the pneumatic actuator is on an improved, self-contained, oil-cooled heavy-duty disc flange arranged. The improved cooled disc brake consists of

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a plurality of rotors having grooves on their surface, and a plurality of stators which are in their Have internal passages, whereby a circuit for oil is established within the disc brake housing. the outer portions of the housing are designed to promote heat exchange, with oil from the housing due to the centrifugal force of the rotors is splashed onto the outer walls of the housing and cooled rapidly. The rotors have a self-pumping effect, reinforced by the grooves worked into their surface, which, together with the heat-exchanging ones Funds on the housing, for a self-employed, independent working cooling of the disc brake is ensured. There is significantly less oil in the housing than the capacity of the housing is, preferably about a third of the oil, that would have room in it, with the oil foaming during operation and a thin layer of oil is always between the rotors and the stators, which increases the service life the structural unit is greatly elongated compared to prior art devices.

It is the primary object of the invention to provide an improved heavy duty disc brake to create with purely pneumatic actuation. These and other objects of the invention will be apparent from US Pat detailed description in conjunction with the drawings and from the claims.

Brief description of the drawings

Fig.la is a side view, partly in section, of one Example of a disc brake assembly with a pneumatic actuation according to the present invention, attached to a truck axle,

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Pig.Ib is a partial side view, partially in section, of the disc brake assembly of FIG. 1 with a different actuator;

Pig. 2 is a perspective view, partly in section, of a modified pneumatic actuator;

Pig. 3 is an outer surface view of an example of a stator plate;

Pig. 4 is an inner surface view of an example of a stator plate;

Pig. Fig. 5 is an edge view of an example of a stator consisting of two stator plates with radial grooves up to its edge;

Fig. 6 is a view of an example of a rotor. Description of the invention in detail

An example of a heavy duty disc brake that accordingly According to the teaching of the present invention, it is indicated generally at 10 in the drawings. A Housing 12 with ends 14 and 16 includes all of the components of the brake assembly. The housing 12 is suitable for a Axle 18 of a vehicle to be braked, e.g. a truck, a trailer or the like. the two ends 14 and 16 of the housing are arranged in the installed state of the unit 10 along the axis 18 at a distance from one another. The housing 12 is preferably a self-contained unit, with no connection to outside of it.

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arranged radiating means or the like is required is. The housing can be cast from aluminum or the like, as can ends 14 and 16 thereof. Inside the case 12, a plurality of rotor disks 22 are provided next to a plurality of stator disks 30. A sleeve 20 is with the Axis 18 is connected by suitable means and the rotor disks are in turn connected to rotate together. Every Rotor disk 22 may carry a plurality of projections 24 which correspond to corresponding projections 26 on the outer periphery of the Sleeve 20 work together. The interengagement of the projections 24 and 26 allows the disks 22 to move relatively to the stator disks 33 along the sleeve 20 and parallel to the axis of rotation of the disks. Preferably, each of the rotors has 22 a plurality of generally radially extending grooves 28 machined in each face thereof, for a purpose to be described later.

Each of the stator disks 30 may consist of a pair of plates 32. Each of the plates 32 can have a plurality be formed by projections 39, which cooperate with a plurality of bolts 40 or the like, which in turn can serve to hold the housing ends 14 and 16 together. The mutual engagement of projections 39 and bolts 4o allows the longitudinal movement of the stator plates 30 along the bolts 40 parallel to the axis of rotation of the disks 22. Each plate 32 has a smooth outer surface 34 to cooperate with a surface of the rotor 22 and an inner surface 35 with a A plurality of radial grooves 37 extending therein from the center to the circumference. Inner surfaces 35 of a pair of Plates 32 are collapsed to form a stator disk 30. As shown in Fig. 5, the plates 32 can be so arranged. be arranged that the grooves 37 are staggered along the circumference or that the grooves 37 of a plate with the grooves of the

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others coincide. The grooves are shown in semicircular cross-section but can be of any other shape, including a triangular cross-section. In reality, no grooves are required at all, only one porous material; between two non-porous smooth ones Areas 34 bordered, this can be equivalent for the later be the purpose described. A pretensioning means such as a spring or springs 42 or the like, is provided to move the rotor and stator disks into the normally far apart relative position of Fig.l to press. The resilient means 42 can be of any suitable construction as long as they are only the disks 22 and 30 apart push away. The outer walls of the housing 12 are provided with projections 44, whereby they have a large surface for Heat transfer between the interior of the housing 12 and its exterior as well as an irregular surface for what is sprayed thereon create oil.

Cooling liquid such as sintered oil (e.g. Shell, Thermia-33) is filled into the housing 12, preferably so that it is about a Third of it fills (dash-dotted line in Fig.l). The disc brake won't work properly if the case is 12 is full of oil, since a free space is required in it. During the operation of the unit, the oil pulls air with it and adopts a foam-like structure instead of a pure liquid. In its foam form, it serves far more effectively for heat transfer than in its liquid form.

During braking, the rotors 22 and the stators are moved towards one another. Come during normal operation however, the surfaces of the rotors and stators never really come together (although a braking effect is also still present is, when they come together), on the other hand there is a very thin film of oil always between the panels, which contributes to the long service life of the building

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unit IO contributes. When the rotors 22 rotate, will oil splashed around inside the case. The oil in the vicinity of the centers of the disks 22 is passed through Centrifugal force thrown in the direction of the Urafang. As well as the Rotors and stators are brought closer together, a closed circuit is created for the oil, oil between the disc is thrown by the centrifugal force outwards against the projections 44 on the outer walls of the housing 12, the grooves 28 in the disks 22 favoring the radially outward movement. When the oil hits the tabs hits, it splatters, dragging air with it and thus providing an extremely effective means of heat transfer to the Housing 12 is. In addition, the projections 44 offer a large surface for the transfer of heat from the interior of the housing to its exterior.

After the oil splashes against the projections 44 and after sufficient movement of oil from the center of the assembly to its periphery creates a negative pressure in the center of the assembly generated. This negative pressure produces a sufficiently large force to allow some of the oil to pass through the perimeter of the assembly to pull the grooves 37 in the stators 30 towards the center. In this way a cycle is created. It should be noted that in the event that the grooves 37 were provided on the outer surface of the plates 32 of the stators 30 instead of in the middle, these grooves would only facilitate the centrifugal pumping action, but not the passage of oil to the center of the assembly would allow. In this way, the oil would become too hot and the structural unit 10 would not be adequately cooled occur. The effectiveness of the brakes would be reduced and their service life shortened. The circuit established is in

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Pig. la represented by arrows. It should be noted that all stators 30 need not have internal grooves 37 or passages as long as there are enough passages for inward movement of a sufficient amount of oil and as long as local hot spots are avoided.

The mutually directed movement of the disks 22 and 30 can be caused by a stator 50 at the end 16 of the housing 12, which is made a little thicker, with a pneumatic actuator 52 or 100 according to the present Invention together to act »e & tai. The pneumatic actuator 52 or 100 represents the relative movement of the Discs 22 and 30 required force available.

The pneumatic actuator shown in Fig.la and 2 52 includes a first piston 54 having a working surface 56 for the application of compressed air, which can be slid in a cylinder 55. Piston 54 and cylinder 55 are annular and suitable to be arranged together with the remaining part of the structural unit 10 around an axis 18 of a vehicle will. An air outlet 58 is in the cylinder 55 in the section provided, which is opposite to the working surface 56 of the piston 54, so that a movement of the piston 54 is not obstructed by compressed air in cylinder 55 under the force of compressed air to the left in Fig.la.

The first piston 54 is by any suitable means e.g., a plurality of rods 60 in operative connection with a second annular piston 64 which is slidable in an annular cylinder 68. the Cylinders 55 and 68 are typically different and pistons 54 and 64 typically have different sized surfaces their work surfaces to the actuation unit 52 in their i To make the operating environment as compact as possible. Of the

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Piston 64 has a working surface 65 to which compressed air can be applied and a surface 66 on the opposite side of surface 65 to rest against the last stator 50 for the relative movement of rotors 22 and stators 50. One of the means for operatively connecting the piston 54 to the piston 64 includes a hollow rod spring 61 with a passage 62 formed therein for air. Air supplied to either of the working surfaces of the pistons 54 or 64 is conveyed through the passage 62 to the working surface of the other piston, the effective surface area exposed to the pneumatic pressure medium being the sum of the working surface 56 of the piston 54 and the working surface 65 of the piston 64 is. In this way, a sufficiently large surface is created for the operation of the structural unit 10 solely with pneumatic means, while the dimensions of the housing 12 are not significantly increased, with an enlargement only along the axis 18 without interfering with the operation of the vehicle and without Increasing the mass of the unit takes place.

Suitable sealing means are between the pistons and 64 in the cylinders 55 and 68 and for the pressure transfer rods 60 and 61 are provided to avoid the passage of air.

Compressed air from a vehicle braking system may be introduced into cylinders 16 and 68 by any suitable means, such as the air inlets 70 and 70 'of Figs. 1 and 2, can be inserted. Inlet 70 is at the furthest back portion of the housing end 16 and provides the air first for the working surface 56 of the first piston 54 and then over the passage for the working surface 65 of the second piston 64 available. The inlet 70 * initially provides the air of the work surface 65 of the

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second piston 64 and then through passage 62 of the working surface 56 of the first piston 54 are available.

Another form of pneumatic actuator that is used to actuate an improved disc brake assembly according to a preferred embodiment of the invention for braking trucks or the like in accordance may be used with the Federal Regulations noted above is indicated generally at 100 in Figure Ib. A case end 116 of the disc brake assembly 10 is provided, the housing having a single annular piston 120 in an annular recess 118 and the direction of movement of the piston 120 is parallel to the axis of rotation of the axis 18.

The piston 120 can be in the annular recess 118 of the housing going back and forth. Sealing means are provided on piston 120 to define fluidized chambers 126 and 128 on each Side of the piston 120 to create. Means for transmitting the movement of the piston 120 to the stator 50 of the brake unit 10 for generating the braking effect are provided and preferably consist of a plurality (in the given example 8) rods 122, each rod 122 being either integral with the piston 120 or attached thereto and in a bore 123 in the Housing end 116 is longitudinally displaceable. Sealants 124 are between each rod 122 and its corresponding bore 123 intended.

The piston 120 is normally pushed to the brake applied position. (to the left in Fig.Ib) by a Biasing spring in actuation chamber 128. The biasing spring means is preferably in the form of a plurality (in the assumed Example 8) IJO conical springs located between the piston and the housing plate T are located in the chamber 128. Preferential

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Tapered springs are used in the interest of saving space. The dimensions of the brake assembly 10 as a whole are important to a truck or the like. If conical springs are used, the recess 118 need not be as large as in the case in which conventional coil springs are used, since in the retracted position of the piston 120 (position of Pig.Ib) only the thickness of one turn of a spring 130 between the Piston 120 and plate II7, instead of having a plurality of turns thick as would be the case with a coil spring. Preferably, the spring constants of the springs I30 are such that the springs apply approximately 60 % of the maximum braking force required to actuate the brake assembly 10. In this way, it is only necessary to apply about βθ % (slightly more) of the force necessary to brake the unit 10 through air introduced into the retraction chamber 126 to retract the piston 120 and only 40 $ (or slightly more) that to brake of the unit 10 by introducing air into the actuation chamber 128 to apply the brakes. The springs I30 also provide a fail-safe mechanism in the event that the compressed air source fails or is switched off, as the brakes apply with 60% of the maximum force (enough to stop the vehicle in an emergency and / or lock the wheels if that Vehicle is parked on a slope), even without compressed air.

Actuation and retraction of piston 120 is provided by one or more sources of compressed air. As shown in Fig. Ib is a special compressed air supply (138 or 13 ^) for the Operation and withdrawal provided. However, only one source and one switching valve can be provided, if this is desired. One of the sources, I38, is through a passage 136 connected to chamber 126, the other source I34 is connected to the chamber 128 via a passage I32. if the operational readiness of the vehicle is desired

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Air under pressure (sufficient to compress springs 1 ^ 0) is supplied to chamber 126 while no pressurized air is supplied to chamber 128 (chamber 128 can be vented instead) . In this way, the piston 120 is withdrawn, depressurization of the stator 50 is effected and the axis 18 is allowed to rotate. When braking of the vehicle is desired, air under pressure from source 1 ^ 4 is supplied to chamber 128 while no air is supplied to chamber 126, which is instead vented. This moves the piston to the left according to the view in FIG. 1b, which in turn causes the relative movement of the rotors and stators and consequently the braking of the axle 18. From this it can be seen that only a little more than 60 % (or whatever force was chosen for the springs) of the braking force really has to be applied by pneumatic means, whereby the pneumatic braking can be carried out in practice.

A mechanical piston puller I ² K) can be provided for the piston 120 in the event that both compressed air sources 134 and 138 fail and movement of the vehicle is desired. The piston puller I4o consists merely of a plurality of sealed rods which protrude away from the piston 120 and out of the housing end 116. The rods 122 can be gripped by any mechanical means and then the piston 120 withdrawn (and locked in the withdrawn position).

It is obvious to the average achmann that many changes can be made within the framework defined by the invention. For example, other means for movably guiding the panes and securing them could be provided, as well as other pretensioning means and other air inlet means.

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Claims (1)

- 14 - cu-ho-lO Claims Liquid cooled disc brake device; marked by a) a housing in which there is less liquid than the capacity of the housing, and that for the preservation of this amount of liquid sealed and with continued preservation of this amount of liquid is operable, b) a plurality of rotor disks which are rotatably mounted with respect to the housing about an axis of rotation within the housing are, c) a connection between the rotor disks and an external rotating body, which is optionally to be braked, d) a mounting of the rotor disks that is relatively movable along the axis of rotation, e) a plurality of stator disks in the housing with essentially flat outer disc surfaces that are at right angles to the axis of rotation, f) an attachment of the stator disks in juxtaposition to the rotor disks and in relative longitudinal mobility along the axis of rotation of the rotor disks below Preventing the rotation of the stator disks, 609832/0692 - 15 - cu-ho-lO g) a preload of rotor and stator disks to keep them in a disengaged position, whereby no braking effect is generated, h) a Wärraeaustauscheinriehtung, which on housing sections is formed which extend generally parallel to the axis of rotation, wherein the heat exchange device includes a plurality of ribs extending outwardly from the housing and generally radially away from the axis of rotation extend i) a closed circuit for the coolant during braking, so that the coolant from a position in near the axis of rotation of the rotor disks is pumped towards the heat exchanger device of the housing .. against which it splashes and is thereby foamed, from where it inwards towards the axis of rotation due to a Negative pressure can get near the axis of rotation, whereby the closed circuit inter alia by internal Passages for the cooling liquid run in at least one of the stator disks, j) a first device for moving the rotors and Stators towards each other against the force of the preload to effect braking. 2. Braking device according to claim 1, characterized gekennz e ici net, that the housing is cast from aluminum. 5. Braking device according to claim 1, characterized in that the amount of fluid contained in the housing is approximately one third of the maximum amount of liquid that can be grasped by the housing. 609832/0692 - 16 - cu-ho-lO 4. Braking device according to claim 1, characterized in that the rotors also in their surfaces Have passages that facilitate the pumping action of the rotors when braking. 5. Braking device according to claim 1, characterized by second means for pressing the disks against one another to effect braking, wherein the second device is independent of the first in its mode of operation. 6. Braking device according to claim 1, characterized in that g e k e η η - ζ ei c h η e t that the heat exchanger device also includes a plurality of ribs extending inwardly from said housing sections and generally radially inward Extend direction towards the axis of rotation. 7. Braking device according to claim 1, characterized through openings in the Stctor disks, which are evenly distributed over the entire device. 8. Braking device according to claim 1, characterized in that the means for preloading rotor and stator disks are resilient to keep them in a disengaged position. 9. Braking device according to claim 1, characterized in that the attachment of the rotor disks according to Kind of a sliding wedge is formed. 10. Braking device according to claim 1, characterized in that the fastening of the stator disks according to Kind of a sliding wedge is formed. 609832/0692 - 17 - cu-ho-lO 11. The device according to claim 1, characterized in that that the first device to move the rotors and stators towards each other is exclusively pneumatic is actuatable. 12. Disc brake device according to claim 11, characterized by the structure of the pneumatically operated Facility from: (i) a first annular piston in an annular cylinder on one End of the housing with a work surface that can be pressurized with compressed air, (ii) a second ring piston in a ring cylinder on the same End of the housing and with a work surface that can be acted upon by compressed air and one opposite it Area for operative connection with one of the panes, (iii) a device for producing an operative connection between the first and second pistons so that movement of a piston in one direction corresponds to movement of the other piston in the same direction entails, (iv) a device for producing a pressure medium connection between the working surfaces of the pistons, (v) a device for connecting the work surfaces of the Piston with a source of compressed air. 13. The device according to claim 12, characterized in that that the device for producing an operative connection between the first and the second piston consists of several rods. 14. The device according to claim 13 *, characterized in that that the means for establishing a pressure medium connection includes an air passage through one of the rods. 609832/0692 - 18 - cu-ho-10 15. Apparatus according to claim 12, characterized in that that the heat exchanger device includes a plurality of projections on the outer walls of the housing, which look inwards and outwards. 16. The device according to claim 12, characterized in that that the closed circuit is also formed by a plurality of generally radially extending grooves runs in the surfaces of the rotor disks, the self-pumping effect of the rotor disks being increased. 17 · Device according to claim 12, characterized in that that the cylinders for the first and the second piston are special and separate cylinders. 18. Device according to claim 17 *, characterized in that that the working area of the first piston is larger than the working area of the second piston. 19. The device according to claim 12, characterized in that that the working area of the second piston is greater than is the working surface of the first piston. 20. Disc brake device according to claim 11, characterized by the structure of the pneumatically operated Facility from: (i) an annular piston in an annular cylinder at one end of the housing, the piston in actuation of the cylinder and divides a retraction chamber, the retraction chamber being closer to the disks than the actuation chamber, (ii) a device for transmitting the force from the piston to the discs to move them, 609832/0692 - 19 - eu-ho-10 (iii) a plurality of conical springs in the actuation chamber between the piston and a stationary part of the housing for biasing the piston to push the discs into braking position, the total force exerted by the springs being sufficiently less than the total actuation force required for effective braking, so that a practically purely pneumatic actuation is possible, (iv) a device for supplying compressed air to the retraction chamber, so that the piston in the cylinder is movable to separate stator and rotor disks into one Position, in which case it is desired to move the disks apart, the device to supply compressed air to the retraction chamber while no compressed air is supplied to the actuation chamber is supplied, and in the case by making the braking position of the discs for effective braking it is asked for; by the device for supplying compressed air to the actuation chamber, compressed air for actuation chamber is supplied while no compressed air is supplied to the retraction chamber. 21. Heavy-duty disc brake device according to claim 20, characterized in that the device for transmitting the force from the piston to the discs a plurality of spaced apart rods extending through the retraction chamber. 22. Heavy-duty disc brake device according to claim 20, characterized in that the device a mechanical retraction device to move the discs 609832/0692 contains > which is operatively connected to the piston and extends through the actuation chamber in a direction outwardly from this chamber, the mechanical retraction device for moving the piston against the preload being detectable by the springs. 609832/0692 Blank page