SE539048C2

SE539048C2 - A vehicle low pressure brake valve arrangement

Info

Publication number: SE539048C2
Application number: SE1450831A
Authority: SE
Inventors: Rydsmo Erik; Axelsson Peter; Haglund Lennart
Original assignee: Autoliv Dev
Priority date: 2014-07-02
Filing date: 2014-07-02
Publication date: 2017-03-28
Also published as: SE1450831A1

Description

TITLE A vehicle low pressure brake valve arrangement DESCRIPTION OF THE INVENTION The present invention relates to a vehicle braking arrangement comprising a braking plate and a link arm arranged to connect the braking plate to a vehicle. The braking plate is movable from a rest position with a certain ground clearance to a braking position where contact is made with the ground. The braking plate further comprises a sealing rim, running circumferentially and being arranged to at least partially contact the ground in the braking position, such that an at least partly enclosed volume then is formed between the braking plate and the ground. The vehicle braking arrangement comprises a low pressure source that is fluidly connectable to the volume via a valve assembly.

In many traffic situations it is desired to acquire an enhanced braking effect, for example at collision situations and when the road grip is lost. One way to achieve an enhanced braking effect is described in US 8356685, where a braking plate may be lowered. When lowered, a vacuum chamber of the plate faces the road, the vacuum chamber being evacuated such that a retaining function is obtained by the plate being pressed against the road due to the lowered pressure in the vacuum chamber. The lowered pressure is obtained by means of a gas generator acting on a so-called Venturi tube.

Gas generators in emergency brakes of this kind are suitably connected to the vacuum chamber via a valve assembly that is arranged to be opened when the braking plate is in the braking position. Due to the relative short time of braking effect, the timing of when opening such a valve assembly is critical for the function of the emergency brake.

Such valve assemblies are for example described in JPH01262238 and DE3025388. However, arrangements of these kinds that employ electromagnets, are unreliable regarding correct timing since several parts such as detectors and a control unit are required to control the electromagnet. All these parts enhance costs and increases the risk of malfunction.

It is therefore an object of the present invention to provide an uncomplicated valve assembly that provides a secure functionality with correct timing for its opening.

Said object is achieved by means of a vehicle braking arrangement comprising a braking plate and a link arm arranged to connect the braking plate to a vehicle. The braking plate is movable from a rest position with a certain ground clearance to a braking position where contact is made with the ground. The braking plate further comprises a sealing rim, running circumferentially and being arranged to at least partially contact the ground in the braking position, such that an at least partly enclosed volume then is formed between the braking plate and the ground. The vehicle braking arrangement comprises a low pressure source that is fluidly connectable to the volume via a valve assembly.

The valve assembly comprises at least one openable portion in a separating layer having a certain thickness with a first side that is arranged to face the ground, and a second side that is arranged to face away from the ground. Said at least one openable portion has a corresponding at least partly circumferentially running weakened portion defining a break line. The valve assembly further comprises at least one break member that is attached to the second side of the separating layer, at least partly inside a corresponding break line. Said at least one break member is arranged to be moved such that the corresponding openable portion is opened at least partly along its break line by means of a decelerating mass acting on said break member when the braking plate reaches the braking position.

According to an example, all break members are positioned inside an enclosure that either is a low pressure source, and/or is connected to at least one low pressure source.

According to another example, each one of said at least one break member comprises a corresponding break part that is attached to the second side of the separating layer, and a corresponding rod part that extends away from the second side of the separating layer and presents a certain angle against said second side. Said rod part has a first end and a second end, where said first end is attached to the corresponding break part.

According to another example, said rod part is arranged to at least indirectly rest against a fixed surface when the braking plate is moved from the rest position to the braking position. Said second end is arranged to move away from the fixed surface when the braking plate has reached the braking position such that said angle is decreased and such that said rod part exerts a bending force on a corresponding break part. Said break part is then arranged to move along with the corresponding rod part such that each corresponding openable portion is opened at least partly along its break line. According to another example, each one of said at least one break member comprises at least one break part that is attached to the second side of the separating layer, and at least one lever part that is attached to and extends away from at least one break part at a certain distance from the second side of the separating layer. The valve assembly comprises at least one moveable part that is movable to and from said lever part. Said at least one moveable part is arranged: to rest against a corresponding lever part when the braking plate is in the rest position, to move away from said lever part when the braking plate is moved from the rest position to the braking position, and to move against said lever part when the braking plate has reached the braking position such that said lever part is pressed towards the second side of the separating layer.

Then, said at least one moveable part exerts a bending force on each corresponding break part via said lever part (32), where said break part then is arranged to move such that each corresponding openable portion is opened at least partly along its break line.

According to another example, each of said at least one lever part is attached to and extends between at least two break parts at a certain distance from the second side of the separating layer.

Other examples are evident from the dependent claims.

A number of advantages are obtained by means of the present invention. Mainly, an uncomplicated valve assembly for a vehicle vacuum emergency brake is provided, having a secure functionality with correct timing for its opening.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described more in detail with reference to the appended drawings, where: Figure 1 shows a schematical side view of a vehicle during normal running with the vehicle braking arrangement in its rest position; Figure 2 shows a schematical side view of a vehicle with the vehicle braking arrangement in braking position; Figure 3 shows a schematical perspective bottom view of a vehicle braking plate; Figure 4 shows a schematical section side view of a first example of a vehicle braking plate in a first state; Figure 5 shows a schematical section side view of the first example of the vehicle braking plate in a second state; Figure 6 shows a schematical cut-open top view of the first example of the vehicle braking plate without break members; Figure 7 shows a schematical cut-open top view of the first example of the vehicle braking plate in the first state; Figure 8 shows a schematical cut-open top view of the first example of the vehicle braking plate in the second state; Figure 9 shows a schematical section side view of a second example of a vehicle braking plate in a first state; Figure 10 shows a schematical section side view of the second example of the vehicle braking plate in a second state; and Figure 11 shows a schematical side view of alternative low pressure sources.

DETAILED DESCRIPTION With reference to Figure 1, showing a side view of a vehicle 1, where the vehicle 1 comprises wheels 2, 3 which are in contact with the ground 4 during normal running. Here, the vehicle 1 is assumed to be running in a forward direction V. At the rear of the vehicle 1, attached to a bottom floor 5, an emergency braking system 6 is arranged and is shown in its rest position during normal running conditions, more or less obscured by the outer body of the vehicle 1, and preferably arranged to not disturb the vehicle's normal ground clearance G.

Figure 2 corresponds to Figure 1, but here the emergency braking system 6 is shown with the braking plate 7 in the braking position. The braking plate 7 has here rapidly been displaced towards the ground to a braking position, for example by means of a pre-loaded spring 8a, as shown in Figure 3, being comprised in a link assembly 8.

With reference to Figure 3, the braking plate 7 comprises a sealing rim 9, running circumferentially and providing a sealing between the braking plate 7 and the ground 4. An enclosed volume 10 is formed between the braking plate 7 and the ground 4 when the braking plate is in the braking position. The volume 10 may not be completely enclosed due to leakage in the sealing rim 9, for example due to unevenesses in the surface of the ground 4.

The emergency braking system 6 comprises a low pressure source 11 that is fluidly connectable to the volume 10 via a valve assembly 12 (not shown in Figure 3).

The low pressure source 11 may be in the form of a low pressure container as shown in Figure 3, but this is only an example. The low pressure source 11 may for example also be in the form of an expanding volume, a Venturi tube, an engine air intake system or similar. An expanding volume may for example be in the form of a tubular airbag that separates two opposing walls, attached to the tubular airbag, when the tubular airbag is inflated.

How the pressure is lowered in the inner volume is not part of this invention, many different arrangements are of course possible.

In the following, the present invention will be described with reference to Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8. Figure 4 shows a side section view of a first example of the braking plate when the braking plate is moved from the rest position to the braking position, and Figure 5 shows a corresponding view when the braking plate is in the braking position. Figure 6, Figure 7 and Figure 8 show a cut-open top view of the first example of the braking plate. Figure 6 shows the valve assembly without any break members, Figure 7 corresponds to Figure 4 and Figure 8 corresponds to Figure 5. According to the present invention, the valve assembly 12 comprises two openable portions 14, 15 in a separating layer 13 having a certain thickness with a first side 13a that is arranged to face the ground 4 and a second side 13b that is arranged to face away from the ground 4. Each openable portion 14, 15 has a corresponding at least partly circumferentially running weakened portion 16, 17 defining a break line. The valve assembly 12 further comprises two break members 18, 29; inside each break line 16, 17 a corresponding first break member 18 and second break member 19 is attached to the openable portions 14, 15 on the second side 13a of the separating layer. The break members 18, 19 are arranged to be moved such that the openable portions 14, 15 are opened at least partly along the break lines 16, 17 by means of a decelerating mass acting on the break members 18, 19 when the braking plate 7 reaches the braking position. In this example, the break line 16, 17 or only partly circumferentially running, but may have a circumferential extension. Furthermore, here the mass acting on the break members 18, 19 is in the break members 18, 19 themselves, and in a connecting rod 26 that will be described below.

More in detail, each break member 18, 19 comprises a corresponding break part 20, 21 that is attached to the openable portions 14, 15 on the second side 13b of the separating layer. Each break member 18, 19 also comprises a rod part 22, 23 that extends away from the second side 13b of the separating layer and presents a certain angle 9 against said second side 13b. Each rod part 22, 23 has a corresponding first end 24a, 25a and second end 24b, 25b, where each first end 24a, 25a is attached to the corresponding break part 20, 21, and the second ends are attached to each other by means of a connecting rod 26. The valve assembly 12 is comprised in a low pressure container 11 positioned on the second surface 13b, having an inner volume VI.

In this example, this means that the low pressure source is in the form of a low pressure container, but that is only an example. The valve assembly 12 should be comprised in a container, but that container does not have to be a low pressure container, but any container that in turn is connected to an external low pressure source of any suitable kind, for example as discussed above. Combinations of low pressure sources are of course conceivable.

The connecting rod 26 is arranged to rest against a fixed surface 27 mounted to the low pressure container 11 when the braking plate 7 is moved from the rest position to the braking position. The connecting rod 26, and thus the second ends 24b, 25b, are arranged to move away from the fixed surface 27 when the braking plate 7 has reached the braking position such that said angle 9 is decreased, and such that the rod parts 22, 23 exert a bending force on the corresponding break part 20, 21, The break parts 20, 21 are arranged to move along with the rod parts 22, 23 such that the openable portions 14, 15 are opened at least partly along the corresponding break lines 16, 17.

In other words, when the braking plate 7 is moved from the rest position to the braking position, the rod parts 22, 23 and the connecting rod 26 are accelerated, and when the braking plate 7 is moved from the rest position to the braking position these parts are rapidly decelerated, continuing their motion due inertia, and performing the opening of the openable portions 14, 15. During the acceleration, the rod parts 22, 23 and the connecting rod 26 are held motionless due to the fixed surface 27.

In the braking position, the valve assembly 12 is opened as described above, and then the pressure is lowered in the volume 10 by means of the low pressure source 11 that becomes fluidly connected with the volume 10. The braking plate 7 is then pressed against the ground 4 by a conferred pressure difference between air outside the volume 10 and air in the volume 10 such that a retaining force between the braking plate 7 and the ground 4 is obtained.

The retaining force is dependent of the magnitude of pressure drop, which in its turn is dependent on the sealing properties of the sealing rim, and the capacity of the low pressure generation.

A second example of a valve assembly 12' will now be described with reference to Figure 9 and Figure 10. Figure 9 shows a side section view of a first example of the braking plate when the braking plate is moved from the rest position to the braking position, and Figure 10 shows a corresponding view when the braking plate is in the braking position.

As shown in Figure 9, the emergency braking system 6' comprises a the valve assembly 12' which in turn comprises a break member 28 that comprises a first break part 30, a second break part 31 and a lever part 32, where the break parts 30, 31 are attached to the openable portions 14, 15 on the second side 13b of the separating layer. The lever part 32 is attached to, and extends between, said break parts 30, 31 at a certain distance from the second side 13b of the separating layer.

The valve assembly 12' comprises a moveable part 33, here in the form of a cylinder, that is movable to and from the lever part 32 along an axis 34 extending perpendicular to the separating layer 13. The cylinder 33 is arranged to rest against the lever part 32 when the braking plate 7 is in the rest position, to move away from the lever part 32 when the braking plate 7 is moved from the rest position to the braking position, and to move against the lever part 32 when the braking plate 7 has reached the braking position. Then the lever part 32 is pressed by the cylinder 33 towards the second side of the separating layer, as shown in Figure 10.

The cylinder 33 then exerts a bending force on the break parts 30, 31 via the lever part 32, where the break parts 30 ,31 then are arranged to move along with the cylinder 33 and the lever part 32 such that the openable portions 14, 15 are opened at least partly along their corresponding break lines 16, 17.

In other words, when the braking plate 7 is moved from the rest position to the braking position, the cylinder 33 is accelerated, and when the braking plate 7 is moved from the rest position to the braking position, the cylinder is rapidly decelerated, continuing its motion due inertia, and performing the opening of the openable portions 14, 15. During the acceleration, the cylinder is pressed against a top roof of the low pressure container 11.

The cylinder 33 may be any form of moveable part such as a suitable weight that runs along the axis 34. In order for the moveable part 33 to run along the axis 34 it is guided in a suitable way, for example by being positioned in a guiding tube 35 as indicated with a dashed line.

In the second example, the mass acting on the break member is separate from the break member.

The invention is not limited to the examples above, but may vary freely within the scope of the appended claims. For example, the link arm 8 is in Figure 3 shown to comprise a spring arrangement 8a which is arranged to enable a quick deployment of the braking plate 7, but other such arrangements are conceivable, such as pyrotechnical deployment arrangements.

The emergency braking system 6 is generally constituted by a vehicle braking arrangement.

Generally, as mentioned previously, the valve assembly 12 should be comprised in a container, but that container does not have to be a low pressure container, but may be a container, or more generally an enclosure, that is connected to a low pressure source. In Figure 11, the valve assembly 12 is schematically indicated to be positioned in a container 36 that is not a low pressure source, and which container 36 is fluidly connectable to a low pressure source 37 via a valve 38 and a tube 39. The low pressure source 37 may for example be a low pressure container, a Venturi tube, an engine air intake, and/or combinations thereof.

There may be any suitable number of break members in a valve assembly 12, 12' according to the present invention, where some may be connected to each other. There may thus be one or more connecting rods 2 6, where a connecting rod may connect two or more rod parts. Independently of if the a rod part is connected to another rod part via a connecting rod or not, at least one rod part may comprise a weight, for example at its second end 24b, 25b, in order to increase the opening functionality. When there is a connecting rod 26, the connecting rod may be equipped with an additional weight.

Depending on configuration of the valve assembly 12, 12', each break member 18, 28 may comprise one or several break parts 20, 21; 30, 31. In the examples above, several break parts may for example be connected to each other in a line and then connected to one or more rod parts or lever parts. In the second example, several break parts may be positioned along a circumference where a star-shaped lever part is connected to each one.

Depending on the configuration in the second example, there may be one or more moveable parts.

The number of openable portions is at least one, the number of break members and the form of the break member being adapted to the number of openable portions. In the second example there may thus be only one openable portion and a break member with only one break part that is attached to a lever part.

Where a break line is partly circumferentially running, a part of the corresponding openable portion may still be connected to the rest of the separating layer 13 and act as a hinge after being opened. Otherwise, if a break line is circumferentially running, the corresponding openable portion will be detached from the rest of the separating layer 13 after being opened.

The parts of the break member may have different sectional shapes such as flat, round and U-shaped.

The separating layer may be of any suitable material, for example in the form of a plastic or metal plate. The separating layer can be smooth or having a suitable surface structure. As an example, the separating layer may have a thickness of about 0,8mm, and the thickness of the break line may be <0,3mm, preferably about 0,15mm. These figures are only provided as an example, other thicknesses and relations between the thickness of the separating layer and the break line are of course possible.

The separating layer, which is comprised in the braking plate 7, may furthermore have different thicknesses at different portions, for example in order to acquire a desired rigidity.

In order to obtain the opening of the openable portions according to the present invention, the deployment of the braking plate from the rest position to the braking position should have a certain speed, for example in the range of 4m/s to 8m/s. Other ranges are of course conceivable. If the deployment is too slow, the effect of the decelerating mass will be to small to open the openable portions.

Claims

1. A vehicle braking arrangement (6) comprising a braking plate (7) and a link arrangement (8) arranged to connect the braking plate (7) to a vehicle (1), the braking plate (7) being movable from a rest position with a certain ground clearance to a braking position where contact is made with the ground (4), where the braking plate (7) further comprises a sealing rim (9), running circumferentially and being arranged to at least partially contact the ground (4) in the braking position, such that an at least partly enclosed volume (10) then is formed between the braking plate (7) and the ground (4), where the vehicle braking arrangement (6) comprises a low pressure source (11) that is fluidly connectable to the volume (10) via a valve assembly (12, 12'), characterized in that the valve assembly (12, 12') comprises at least one openable portion (14, 15) in a separating layer (13) having a certain thickness with a first side (13a) that is arranged to face the ground (4), and a second side (13b) that is arranged to face away from the ground (4), said at least one openable portion (14, 15) having a corresponding at least partly circumferentially running weakened portion (16, 17) defining a break line, where the valve assembly (12) further comprises at least one break member (18, 19; 28) that is attached to the second side (13b) of the separating layer (13), at least partly inside the corresponding break line (16, 17), said at least one break member (18, 19) being arranged to be moved such that the corresponding openable portion (14, 15) is opened at least partly along its break line (16, 17) by means of a decelerating mass acting on said break member (18, 19; 28) when the braking plate (7) reaches the braking position.

2. A vehicle braking arrangement (6) according to claim 1, characterized in that all break members (18, 19; 28) are positioned inside an enclosure (11, 36) that either is a low pressure source, and/or is connected to at least one low pressure source (37).

3. A vehicle braking arrangement (6) according to any one of the claims 1 or 2, characterized in that each one of said at least one break member (18, 19) comprises a corresponding break part (20, 21) that is attached to the second side (13b) of the separating layer (13), and a corresponding rod part (22, 23) that extends away from the second side (13b) of the separating layer (13) and presents a certain angle (9) against said second side (13b), said rod part (22, 23) having a first end (24a, 25a) and a second end (24b, 25b), where said first end (24a, 25a) is attached to the corresponding break part (20, 21).

4. A vehicle braking arrangement (6) according to claim 3, characterized in that said rod part (22, 23) is arranged to at least indirectly rest against a fixed surface (27) when the braking plate (7) is moved from the rest position to the braking position, and where said second end (24b, 25b) is arranged to move away from the fixed surface (27) when the braking plate (7) has reached the braking position such that said angle (9) is decreased and such that said rod part (22, 23) exerts a bending force on a corresponding break part (20, 21), where said break part (20, 21) is arranged to move along with the corresponding rod part (22, 23) such that each corresponding openable portion (14, 15) is opened at least partly along its break line (16, 17).

5. A vehicle braking arrangement (6) according to any one of the claims 3 or 4, characterized in that two or more rod parts (22, 23) are attached to each other at their second ends (24b, 25b).

6. A vehicle braking arrangement (6') according to claim 1, characterized in that each one of said at least one break member (28) comprises at least one break part (30, 31) that is attached to the second side (13b) of the separating layer (13), and at least one lever part (32) that is attached to and extends away from at least one of said least one break part (30) at a certain distance from the second side (13b) of the separating layer (13), where the valve assembly (12') comprises at least one moveable part (33) that is movable to and from said lever part (32), where said at least one moveable part (33) is arranged to rest against one corresponding lever part (32) of said at least one lever part (32) when the braking plate (7) is in the rest position, to move away from said lever part (32) when the braking plate (7) is moved from the rest position to the braking position, and to move against said lever part (32) when the braking plate (7) has reached the braking position such that said lever part (32) is pressed towards the second side (13b) of the separating layer (13), such that said at least one moveable part (33) exerts a bending force on each corresponding break part (30, 31) via said lever part (32), where said break part (30, 31) then is arranged to move such that each corresponding openable portion (14, 15) is opened at least partly along its break line (16, 17).

7. A vehicle braking arrangement (6') according to claim 6, characterized in that each of said at least one lever part (32) is attached to and extends between at least two break parts (30, 31) at a certain distance from the second side (13b) of the separating layer (13).

8. A vehicle braking arrangement (6) according to any one of the previous claims, characterized in that when the valve assembly (12) is opened, the pressure is lowered in the volume (10) by means of the low pressure source (11), and the braking plate (7) is pressed against the ground (4) by a conferred pressure difference between air outside the volume (10) and air in the volume (10) such that a retaining force between the braking plate (7) and the ground (4) is obtained.

9. A vehicle (1) comprising the vehicle braking arrangement (6, 6') according to any one of the claims 1-8.