DE1555603A1 - Hydraulic braking system - Google Patents

Description

Monsieur GRATZMULLER Neuilly / France

Hydraulic braking system

The present invention relates to a hydraulic brake system
and relates in particular to the braking of one or more wheels that run with a surrounding pneumatic tire on one or more surfaces with changing grip conditions and wherein the contact pressure between the wheel tires and the treads can fluctuate within wide limits.

The invention is generally applicable to hydraulically operated brake systems with at least one master cylinder, its
Piston can be actuated from the outside and to which at least one brake cylinder is connected via a line filled with brake fluid, the resp. whose pistons in turn actuate the braking devices,

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The invention is applied to such hydraulic brake systems characterized in that a further pressure cylinder containing a freely displaceable piston with its the brake fluid containing chamber is connected to the hydraulic line in parallel, this pressure cylinder having an elastic counterforce exerts on the hydraulic line, the maximum value of which is approximately that for non-slip braking under the most unfavorable grip conditions required braking force, and wherein the hydraulic line is designed so that the freely movable piston of the pressure cylinder

.the
is held in the rest position by / elastic counterforce on a line-side stop.

This arrangement results in an automatic limitation of the braking force to a maximum permissible value under the most unfavorable conditions Adhesion conditions so that the wheel tires cannot slip or slide on the rolling surface, which is a major reason for a represents rapid wear and tear.

The brake system designed according to the invention is particularly advantageous for those cases in which the braking is controlled automatically, ie without the involvement of a brakeman who sets or selects the braking force depending on the respective circumstances, the grip conditions and the desired braking intensity.

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It is particularly advantageous to use the invention as follows will be described in the case of facilities in which the vehicles or wagons to be braked trigger the braking themselves by they actuate the piston of the master cylinder.

In this case, the controllability of the pressure in the mentioned pressure cylinder and the stroke length of its piston, which affects the actuators for the vehicles to be braked, a brake pressure of constant value, even if the differences in the dimensions of the vehicle parts, which act on the brake actuators, relatively large are. As already mentioned above, this constant value of the brake pressure corresponds to a maximum permissible braking under the most unfavorable conditions.

In a preferred embodiment of the invention, the pressure cylinder consists of an oil-pneumatic cylinder, the aforementioned elastic counterforce is exerted by a pressurized gas cushion. According to a further embodiment of the invention is a brake fluid containing reservoir with relatively low internal pressure is provided, which preferably also consists of an oil-pneumatic pressure cylinder and likewise parallel to the hydraulic line with the interposition of a

009849/0309 BAD ORJOLNAt.

Only a non-return valve that is permeable in the direction of the line is connected which means that the hydraulic line is always kept full of brake fluid will.

In a particularly expedient and advantageous form of application the inventive piston of the master cylinder is about vertically arranged and pivotally mounted at its lower end axis or shaft actuated, which is a free at its upper end running wheel provided with a brake drum, which when running on the side surface of a car to be braked under Pivoting of the vertical axis or shaft is braked.

The invention is illustrated below by the description of some exemplary embodiments explained in more detail in connection with the attached drawing, in which show:

Fig. 1 in a schematic representation of a simple embodiment -

form of the brake system according to the invention;

Fig. 2 shows a modification of this with a device for

Interruption of the braking process without the piston of the master cylinder moving back into its rest position will;

009849/0309

BAD ORfGJN ^. .. .., '.- .;

Fig. 3 shows a preferred embodiment of the invention, wherein

an automatic braking of rolling carriages, e.g. B. tram, takes place;

Fig. 4 shows the same arrangement according to Fig. 3, but in braking

position, while in Fig. 3 the system in the rest position is shown;

5 shows a part of the hydraulic line in a simplified one

Execution.

The brake system shown schematically in Fig. 1 contains the essentials Elements of a conventional hydraulic brake system, in particular a master cylinder 2, the piston 4 of which can be actuated from the outside by means of a suitable device which is simplified in the drawing is represented by a brake lever 6. This master cylinder 2 is via a hydraulic line 8 with one or more brake cylinders 10 connected, whose piston or pistons 12 act on one or more brake shoes or brake pads 14. These brake shoes or brake pads 14 come in turn when the brake is applied to the braking surface of a drum or a disc to the plant, which is firmly attached to a Wheel 16 are arranged. A return spring 18 brings the brake shoes or blocks when the braking process is canceled in their starting position

009 849/030 9

BAD ORIGIIsfaÜ, '' "

ment back.

According to the invention, a further pressure cylinder 20 is now by means of a Line 22 is connected to the hydraulic line 8 and parallel thereto. This pressure cylinder 20 contains a freely displaceable piston 24, which the interior of the cylinder into a lower, brake fluid containing chamber 26 and an upper causing an elastic counterforce Chamber 28 divides. This elastic counterforce is preferably obtained by a pressurized gas cushion, which is filled into the upper chamber 28 of the pressure cylinder 20 through a valve 30. In the rest position of the brake system shown in Fig. 1 is the freely displaceable piston 24 of the oil-pneumatic pressure cylinder 20 at the lower end of its stroke at the bottom of the with Brake fluid-filled chamber 26 or at a corresponding

* Stop on.

This rest position, the freely displaceable piston 24 on a lower stop rests, can be achieved that the Hydraulic line designed accordingly and filled with brake fluid is or by setting the rest position of the piston 4 in the master cylinder 2, for example by means of a controllable, on the The stop acting on the piston 4 or the lever 6, or by a controllable stop for the freely displaceable piston 24.

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The upper chamber 28 of the pressure cylinder 20 is filled with a gas, e.g. Nitrogen, filled with a predetermined pressure P, the corresponds approximately to the maximum permissible pressure acting on the brake cylinder 10, in order to ensure a non-slip braking of the person to be braked To achieve wheels under the most unfavorable grip conditions.

If now, by actuating the brake lever 6, a force Q is exerted on the piston 4 of the master cylinder 2 and on the brake cylinder a pressure Pi is transmitted, which is so great that with bad Liability conditions there is a risk of sliding or slipping, an amount of brake fluid corresponding to the difference P ^ - P arrives into the pressure cylinder 20, the piston 24 of which rises as a result.

The pressure cylinder 20 is designed so that the increase of the piston 24 only a relatively small increase ρ of the pressure of the hydraulic line and the total pressure P + ρ does not exceed a maximum value for braking without sliding or sliding under the most unfavorable grip conditions is permissible.

It follows that by applying the invention, how

the braking force exerted by the brake lever 6 is also large, even if this force is above a predetermined value Q,

009849/0309 ORIGINAL BATHROOM

a braking force is always obtained which is almost constant and is at the maximum permissible braking value. Such Brake system can be used with particular advantage in a device for automatic braking where the brake lever 6 is operated without taking into account the respective conditions and without controlling the braking force. For example, it is sufficient to use in simple way to determine that the lever 6 must cover at least a distance a, which is sufficient to at least a small amount of brake fluid in the pressure cylinder 20 to push, and you get in all cases an almost constant brake pressure, how large the total distance actually covered of the brake lever is too.

In the modification shown in FIG. 2, the brake system contains also a memory 32 for the brake fluid with a relatively large amount low internal pressure, which is also connected in parallel to the hydraulic line 8, via a line 34 into which a check valve 36 is installed.

This brake fluid reservoir 32 preferably consists of one another oil-pneumatic pressure cylinder, which, however, has a much lower internal pressure, e.g. on the order of ten times the order of magnitude less than the other pressure cylinder 20 has. With this out

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ORIGINAL BATHROOM -

A further valve 38 is also provided as a guide, which is closed in the normal rest position and is arranged in a secondary line parallel to the check valve 36. This valve 38 can manually, mechanically, electromagnetically or in any other suitable manner and allows temporary relief of the hydraulic line 8, i.e. releasing the brake without the brake lever 6 being returned to its rest position, while the Hydraulic line 8 for carrying out the braking process under pressure stands as shown in FIG.

In this position, the brake lever 6 presses on the piston 4 of the master cylinder 2 and the brake fluid comes under this pressure on the one hand in the brake cylinder 10 and on the other hand in the lower chamber 26 of the pressure cylinder 20 as soon as the pressure in the hydraulic line 8 reaches the constant value P or P + ρ as explained above is. The hydraulic line is in this case through the valves 36 and 38 kept closed. If the brake lever 6 is held in this braking position, for example by the element 42 of an automatic Brake actuation, it is sufficient to counteract the action of the valve 38 To open the spring 40 temporarily in order to let the pressure in the hydraulic line 8 drop, since this causes the brake fluid to flow out of the chamber 26 of the pressure cylinder 20 and partly from the brake cylinder 10 in the pressure cylinder 32 can enter with low internal pressure and the

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freely displaceable piston 24 comes to rest under the action of the gas cushion in the chamber 28 at its lower stop.

If thereupon the external action of the element 42 ceases, for example by a process which is described below in connection 3 and 4 will be described, the ratio is massive low pressure of the pressure cylinder 32 to remove the brake fluid from this pressure cylinder while raising the check valve 36 to press into the master cylinder 2, whereby the piston 4 and the brake lever 6 moved back into their rest position will.

The entire braking system is then ready for the next braking operation.

In the embodiment shown in Fig. 5, the check valve

36 and the externally operable valve 38 to form a single valve

37 united, its cone 39 like the cone of a check valve works, which, however, can be temporarily lifted from its valve seat to interrupt the braking process, and by a plunger 41 which is actuated by hand, electromagnetically, mechanically or the like.

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Normally the pressure in the hydraulic line 8 holds the valve cone 39 on its seat, but a weak spring 43 can be provided which, together with a spring 35, the return movement of the plunger 41 in the rest position, so that the valve cone 39 does not affect the friction of the plunger 41 within the valve body needs to overcome.

The embodiment of the invention as shown in Fig. 3 in the rest position and is shown in Fig. 4 in the working position, represents a special advantageous and expedient application in an automatic Braking device, which is intended to be on a Platform 46 to stop rolling trams44.

Axles or shafts 6 are arranged on both sides of the track 46, of which only one is shown in the drawing and the one on her at the top end a free-running wheel 16 with a pneumatic tire 48. This wheel 16 is fixed to a brake drum 50 or a similar one acting, cooperating with brake shoes or blocks Braking surface connected. The approximately vertically arranged axle 6 is seated with its lower end in a fixed fork joint 52 and is pivotable about a pin 54 arranged parallel to the rails by an angle α as soon as a trolley 44 is at the braking point arrives and the wheel 16 with its pneumatic tire 48 on the

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Side surface of the cart or preferably on a roll strip 42 runs up against the side of the car. Braking is then sufficient of the wheel 16 to stop the trolley, for example to tilt it for emptying.

The braking system also contains the same elements, as described in connection with FIG. 2, the corresponding elements having the same reference numerals. The axis 6 acts here as a brake lever 6, the mode of operation of which has already been described. The master cylinder 2 is on one fixed point 56 articulated, while the brake cylinder 10 is pivotable seated on a support arm 58 which is fixedly arranged on the axis 6. The rod 60 of the piston 12 can with the brake shoes within the Brake drum 50 with the interposition of a control linkage 62 connected, which is provided with several holes for adjustment.

The operation of this arrangement is the same as that used in conjunction has been described with FIG. 2, in particular by this braking system in the absence of a trolley on track 46 returns to its starting position according to FIG. 3, namely below the effect of the pressure cylinder 32 with low internal pressure, which the brake fluid through the check valve 36 in the hydraulic

0098

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\ r. \ - Ah '■' ■ -

- 13
• Let line 8 flow back.

As soon as a truck arrives at the braking point (Fig. 4), presses this the shafts 6 depending on the carriage width, the construction tion differences, the track profile, etc. more or less by one Angle a to the side and the wheel 16 is automatically braked, as described above, by the inventive Arrangement of the pressure cylinder 20 with an always constant braking force.

The system is set up in this way, and in particular the rest position of the carriage 16 opposite the track 46 so that, taking into account different widths of the trolley, in front especially the narrowest car, the angular shift a of the shaft at the same time as the piston 4 is displaced, at least a small amount of brake fluid enters the pressure cylinder 20 leaves. In this way, it is certain that in this case, too, the braking process will be carried out with a predetermined one, due to the dimensions of the pressure cylinder 20 given brake pressure takes place.

In the places where the carriage widths are at the upper limit, the displacement of the piston 4 naturally creates a lot larger amount of brake fluid moves, but then the

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excess amount in the printing cylinder 20 according to the invention entry.

In this way, the brake pressure and the system are always pressure of the pneumatic tire 48 on the rolling strip 42 of the trolley always constant at a value which is selected so that a Sliding or sliding even under the most unfavorable grip conditions, if, for example, the braking surfaces are damp, is excluded.

This avoids premature wear of the pneumatic tires by sliding or sliding, which is particularly important in such devices It is important that several thousand braking operations are carried out per day.

However, the adjustment of such a brake system generally leads in the course of time to a more or less large reduction in the distance between the shaft 6 and the center of the trolley, which, however, cannot be checked continuously. It can therefore be relatively long way of the piston 4 form dangerous overpressures in the usual hydraulic lines. However, this disadvantage is increased by the Arrangement according to the invention avoided with certainty, since this

BATH ORIGINAL

due to the contact pressure and brake pressure set at the beginning is maintained in the same amount.

In the illustration according to FIG. 4 it can be seen that as soon as a trolley is stopped, the brake lever or the shaft 6 is held in the braking position. To solve these braking, it is sufficient then the valve 38 _s of mechanical or temporarily open hand, drops whereby the brake pressure on the value of the pressure cylinder 32 with a low internal pressure. As soon as the trolley is moved by hand or by a gradient in the tracks, the brake system returns to its starting position as described above, under the action of the gas cushion in the lower chamber of the pressure cylinder 32, which presses the brake fluid back into the master cylinder 2.

009949/0309

Claims (9)

PATENT CLAIMS: 1. Hydraulic braking system with at least one master cylinder, whose piston can be actuated from the outside and to which at least one brake cylinder is connected via a hydraulic line, whose piston or pistons actuate the braking elements, characterized in that that another, a freely movable piston (24) containing pressure cylinder (20) with its chamber (26) containing the brake fluid on the hydraulic line (8) parallel is connected for this purpose, this pressure cylinder exerting an elastic counterforce on the hydraulic line, the maximum value of which corresponds approximately to the braking force required for non-slip braking under the most unfavorable grip conditions, and where the Hydraulic line is designed so that the freely movable piston of the printing cylinder in the rest position due to the elastic counterforce is held against a line-side stop. . 2. Brake system according to claim 1, characterized in that the pressure cylinder (20) is an oil-pneumatic cylinder and contains a pressurized gas cushion as an elastic counterforce. 009849/0309 3. Brake system according to claim 1, characterized in that the pressure cylinder (20) contains a spring as an elastic counterforce. 4. Brake system according to claim 1, characterized in that a Brake fluid containing memory (32) with relatively low internal pressure in parallel on the hydraulic line (8) with the interposition of a non-return valve that is permeable in the direction of the line (36) is connected. 5. Brake system according to claim 4, characterized in that the memory (31) consists of a further pressure cylinder. 6. Brake system according to claim 4 and 5, characterized in that that parallel to the check valve (36) another one from the outside check valve that can be actuated against the action of a spring (40) (38) is arranged, when actuated, an outflow of the pressurized brake fluid into the memory (32) and thus the braking process is interrupted without the Piston (4) of the main cylinder (2) is moved back into its rest position. 7. Brake system according to claim 6, characterized in that the two check valves to a valve (37) with a common 009849/0309 - 18 seeds valve cones (39) are combined. 8. Brake system according to claim 1-7, characterized in that the piston (4) of the master cylinder (2) of an approximately vertically arranged under its lower end pivotally mounted shaft (6) is actuated, which at its upper end a free-running, with a brake drum (5) provided wheel (16) carries the when running is braked on the side surface (42) of a carriage (44) to be braked while pivoting the vertical shaft. 9. Brake system according to claim 8, characterized in that the second check valve (38) by hand, mechanically or electromagnetically is actuatable. 009849/0309