U.S. patent application number 09/727731 was filed with the patent office on 2001-08-16 for actuator module for a vehicle brake and vehicle brake with such an actuator module.
Invention is credited to Franz, Siegfried, Mohr, Kurt.
Application Number | 20010013450 09/727731 |
Document ID | / |
Family ID | 7869764 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013450 |
Kind Code |
A1 |
Mohr, Kurt ; et al. |
August 16, 2001 |
Actuator module for a vehicle brake and vehicle brake with such an
actuator module
Abstract
The invention relates to an actuator subassembly for a vehicle
brake with a drive, which is connected to an input side of a lever
arrangement, wherein an output side of the lever arrangement is
adapted to operate at least one friction element of the vehicle
brake. If a vehicle brake of this kind is used as a parking brake,
static preloading forces occur at the friction element. In order
that these forces may still be taken up within the actuator
subassembly, it is proposed that the lever arrangement be changed
over from a service brake region, in which it is self-releasing,
beyond its force reversal point into a parking brake position, in
which it is self-locking. Various operating possibilities for an
actuator subassembly of this kind and the use thereof in a vehicle
brake are described.
Inventors: |
Mohr, Kurt; (Halsenbach,
DE) ; Franz, Siegfried; (Koblenz, DE) |
Correspondence
Address: |
MACMILLAN SOBANSKI & TODD, LLC
ONE MARITIME PLAZA FOURTH FLOOR
720 WATER STREET
TOLEDO
OH
43604-1619
US
|
Family ID: |
7869764 |
Appl. No.: |
09/727731 |
Filed: |
December 1, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09727731 |
Dec 1, 2000 |
|
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PCT/EP99/03274 |
May 12, 1999 |
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Current U.S.
Class: |
188/106F ;
188/106R |
Current CPC
Class: |
F16D 2121/24 20130101;
B60T 13/686 20130101; F16D 2123/00 20130101; B60T 13/148 20130101;
F16D 2125/68 20130101; F16D 65/18 20130101; F16D 2121/14 20130101;
F16D 2125/40 20130101 |
Class at
Publication: |
188/106.00F ;
188/106.00R |
International
Class: |
F16D 065/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 1998 |
DE |
19824771.0 |
Claims
1. Actuator subassembly for a vehicle brake with a drive (100),
which is connected to an input side of a lever arrangement (102),
wherein an output side of the lever arrangement is adapted to
operate at least one friction element (104) of the vehicle brake,
characterised in that the lever arrangement (102) can be changed
over from a service brake region, in which it is self-releasing,
beyond its force reversal point into a parking brake position, in
which it is self-locking.
2. Actuator subassembly according to claim 1, characterised in that
the lever arrangement (102) lies against a stop (118) in the
parking brake position.
3. Actuator subassembly according to claim 1 or 2, characterised in
that a second mobile stop (120) either confines the lever
arrangement (102) in the service brake region or allows it to move
into the parking brake position.
4. Actuator subassembly according to claim 3, characterised in that
the second mobile stop (120) is coupled to the lever arrangement
(102), wherein tensile and compressive forces can be
transmitted.
5. Actuator subassembly according to claim 3 or 4, characterised in
that an electrically controllable actuating device (122) operates
the second mobile stop (120).
6. Actuator subassembly according to claim 5, characterised in that
the second mobile stop (120) is stable in the absence of current in
the position which confines the service brake region.
7. Actuator subassembly according to any one of the preceding
claims, characterised in that the drive (100) comprises an electric
motor (124) with a spindle drive (126).
8. Actuator subassembly according to claim 7, characterised in that
the spindle drive (126) is self-releasing.
9. Actuator subassembly according to claim 8, characterised in that
the electric motor (124) is a unidirectional motor.
10. Actuator subassembly according to any one of the preceding
claims, characterised in that the lever arrangement (102) comprises
a lever (128) on which a force (F) can act via an operating
device.
11. Actuator subassembly according to claim 10, characterised in
that the operating device of the lever (128) is constructed as a
mechanical appliance which can be manually operated.
12. Actuator subassembly according to claim 10 or 11, characterised
in that the operating device of the lever (128) comprises an
electrically operable second drive.
13. Actuator subassembly according to any one of claims 10 to 12,
in so far as this refers back to claim 3, characterised in that the
operating device of the lever (128) is mechanically coupled to the
second mobile stop (120).
14. Actuator subassembly according to either of claims 12 and 13,
in so far as this refers back to claims 12, 7 and/or 5,
characterised in that the electrically controllable actuating
device of the second mobile stop (120), and the electric drives of
the operating device of the lever (128) and of the spindle drive
(126) are supplied by either separate or common voltage
sources.
15. Actuator subassembly according to any one of the preceding
claims, characterised in that the lever arrangement comprises two
arms (108, 110), the first arm (108) of which is half as long as
the second arm (110), wherein the first arm (108) is hinged at its
first end to the second arm (110) in the centre of the latter and
is supported by way of its second end in a locating bearing (112),
and the second arm (110) is connected at its first end via a
movable bearing (114) to the axially displaceable friction element
(104) and is optionally loaded at its second end via the drive
(100) with a force acting in the direction of the locating bearing
(112).
16. Vehicle brake, characterised by at least one actuator
subassembly according to any one of the preceding claims.
17. Vehicle brake according to claim 16, characterised in that a
respective actuator subassembly according to any one of claims 10
to 15, in so far as this refers back to claim 10, is disposed on
each wheel brake of at least one axle, wherein the levers (128) of
the actuator subassemblies can be operated by a common operating
device with the force (F).
Description
[0001] The invention relates to an actuator subassembly for a
vehicle brake and a vehicle brake with an actuator subassembly of
this kind.
[0002] Brake equipment in the vehicle brake field generally
comprises a service brake system and a parking brake system.
[0003] It is also usual to provide each vehicle wheel with a brake
having a disc- or drum-shaped friction surface as well as a
friction element and an actuator, which presses the friction
element against the friction surface when the brake is operated.
The subassembly comprising the actuator and the friction element is
called "actuator subassembly" in the following.
[0004] In a motor vehicle the service and the parking brake system
generally employ a common brake, whereas their operating and
transmission devices are separate. This is required for safety
reasons and on account of legal regulations.
[0005] In this respect the operation of the actuator subassembly
for a service brake function is usually effected by the pedal force
and an auxiliary force, with pneumatic (vacuum, compressed air),
hydraulic and also electrical energy primarily being used to
produce the auxiliary force. In contrast, the parking brake system
is generally operated manually, by hand or foot, and maintained in
this state by mechanical means.
[0006] The object of more recent developments of vehicle brakes is
also to perform the parking brake function by means of auxiliary
energy, such as, e.g. electrical energy, in order to simplify the
brake system. A further aim is to minimise the constructional
volume and the weight of the brake at the wheel in order to keep
the unsprung mass of the motor vehicle as low as possible.
[0007] Where known vehicle brakes are concerned, the holding force
for a parking brake function is applied by means of auxiliary or
external energy directly by a drive of the actuator subassembly. In
this connection locking and emergency release devices are required
in case the power supply for the drive, e.g. the electricity supply
of an electric motor, should fail, so that the parking brake
initially remains locked and can be released if required. Devices
of this kind are expensive and in some cases require a considerable
amount of power for the drive.
[0008] The applicant's publication WO 98/01682 discloses an
actuator subassembly in which a drive can move a friction element
of the vehicle brake via a toggle arrangement. This actuator
subassembly can also perform the function of a parking brake by
introducing an additional input force into the toggle arrangement.
However the fact that a permanent, very high holding force has to
be applied while operating the parking brake proves to be
problematic in this respect.
[0009] The object of the invention is therefore to provide an
actuator subassembly for a vehicle brake which does not have these
disadvantages. This object is achieved by the actuator subassembly
indicated in claim 1. Subclaims relate to advantageous
developments. Further features, advantages and properties of the
invention are illustrated on the basis of the following description
with reference to the drawings.
[0010] FIG. 1 shows an embodiment of an actuator subassembly
according to the invention in a part-sectional side view, with a
lever arrangement positioned in the service brake region.
[0011] FIG. 2 shows an actuator subassembly according to claim 1
with the lever arrangement in the parking brake position.
[0012] FIG. 1 represents an embodiment of an actuator subassembly
according to the invention with a drive 100, which is connected to
an input side of a lever arrangement 102, which transmits an
introduced driving force to a friction element 104, which is
thereby pressed against a brake disc 106.
[0013] The illustrated lever arrangement with two arms 108 and 110,
the first arm 108 of which is half as long as the second arm 110,
is particularly suitable for carrying out the concept according to
the invention. The first arm 108 is hinged at its first end to the
second arm 110 in the centre of the latter and is supported by way
of its second end in a locating bearing 112. The second arm 110 is
connected at its first end via a movable bearing 114 to the axially
displaceable friction element 104 and is optionally loaded at its
second end via the drive 100 with a force acting in the direction
of the locating bearing 112. Both the drive 100 as well as the
locating bearing 112 and the movable bearing 114 of the friction
element 104 are loaded without any transverse force as a result of
this particularly advantageous configuration.
[0014] The lever arrangement 102 is self-releasing in the state
represented in FIG. 1. If the force which is introduced is reduced,
the friction element 104 is therefore returned on account of its
preload, without this movement being inhibited by the lever
arrangement 102.
[0015] FIG. 2 represents the actuator subassembly according to
claim 1 in a state in which the lever arrangement 102 is in the
parking brake position.
[0016] In a further configuration of the invention the lever
arrangement 102 comprises a force reversal point which lies on an
axis 116. By moving the lever arrangement 102 beyond this force
reversal point, the lever arrangement can be changed over from the
service brake region into a parking brake position. The lever
arrangement 102 expediently lies against a stop 118 in this
position, so that it is maintained in this position.
[0017] The lever arrangement 102 is self-locking in this position.
If the driving force which is introduced is cancelled, the friction
element 104 is prevented from executing a return movement by the
lever arrangement 102. The preloading force of the friction element
104, which is pressed against the brake disc 106, is thereby taken
up within the brake. This signifies a considerable advantage, as no
force acts on the operating device of the vehicle brake in the
parking brake position. The operating device of the vehicle brake
can therefore be formed in a simpler and less expensive manner. The
fact that the parking brake position can be maintained
independently of operating and transmission devices of the vehicle
brake makes the brake system safer.
[0018] As in the case of the preferred embodiment of the invention,
the lever arrangement 102 can easily be held in the parking brake
position by means of a mechanical stop disposed in a stationary
fashion on the housing or similar limiting means.
[0019] The preloading force between the friction element 104 and
the brake disc 106 which is maintained by the lever arrangement is
in this case dependent on the distance of the stop 118 from the
axis 116. The smaller this distance, the greater the preloading
force which is transmitted by the lever arrangement 102 to the
friction element 104.
[0020] A further hydraulic transmission stage may optionally also
be disposed between the lever arrangement 102 and the friction
element 104 in order to increase the force applied by the friction
element 104 to the brake disc 106. It is also possible to dispose
resilient compensating members such as, e.g. wave washers, between
these two elements in order to facilitate the movement of the lever
arrangement 102 beyond its force reversal point and compensate for
wear of the friction element 104.
[0021] While a particularly advantageous embodiment of the lever
arrangement 102 is shown in FIGS. 1 and 2, other lever arrangements
are conceivable. For example, the arm 108 may be omitted and the
service brake region of the lever arrangement 102 confined by a
stop on the arm 110 in a simplified construction of the arm
108.
[0022] On account of legal safety regulations, the vehicle brake
may not be changed over to the parking brake position when in the
service brake state without operating the parking brake system. In
order to meet this requirement, a second mobile stop 120 is
therefore advantageously provided which either confines the lever
arrangement 102 in the service brake region or allows it to move
into the parking brake position. This prevents the vehicle brake
from taking up the parking brake position when this is not
desired.
[0023] As a result of coupling a mobile stop 120 of this kind to
the lever arrangement 102, it is also possible to apply both
compressive forces which confine the service brake region and
tensile forces which can change the lever arrangement 102 over from
the maximum position of the service brake region into the parking
position. The lever arrangement 102 may thus be moved into and/or
out of the parking brake position by means of the mobile stop 120.
An arrangement of this kind can satisfy the legal requirement for a
separate operating device for the service and parking brake.
[0024] It is also possible for the mobile stop 120 to be operated
by an electrically controllable actuating device. In this case it
is particularly advantageous for the second mobile stop 120 to be
stable in the absence of current in the position which confines the
service brake region, so that the energy consumption is minimal
during the service brake function. A bistable change-over switch,
for example, which is only energised when operated, may be used for
this purpose. A moving magnet is used as actuating device in the
embodiment represented in FIGS. 1 and 2 in order to achieve
particularly high operating forces.
[0025] The drive 100 comprises an electric motor 124 with a spindle
drive 126. An actuator subassembly of this kind may therefore be
used in a vehicle brake of the so-called brake-by-wire type.
Particular advantages are achieved if the spindle drive 126 which
is used is self-releasing, for the self-releasing action of the
toggle arrangement 102 is fully effective in a case of this kind.
However it should be borne in mind that self-locking of the lever
arrangement 102 is also necessary if the spindle drive 126 is not
of self-locking construction, as self-locking of the spindle drive
126 would not in itself be sufficient also to maintain the parking
brake function under changing environmental influences (e.g.
cold-heat load). When using a self-releasing spindle drive 126, the
electric motor 124 may be a unidirectional motor, which is of a
compact design and has a low current consumption. A motor of this
kind can be operated at low voltage.
[0026] The lever arrangement 102 comprises a lever 128 on which a
force F acts via an operating device. The lever 128 is in this
respect preferably formed such that it extends out of the housing
of the actuator subassembly.
[0027] On account of the lever principle, the relatively long lever
128 enables a small operating force F of the operating device to be
converted into a large output force on the friction element 104.
The operating device of the lever 128 may therefore be constructed
as a mechanical appliance which can be manually operated, e.g. a
known hand brake lever with a traction cable transmission can be
used here.
[0028] However it is advantageous for the operating device of the
lever 128 to comprise an electrically operable second drive in
order to obtain a vehicle brake which can be operated purely by
electrical means. A combination of a manually operable operating
device of the lever 128 with an electrically operable second drive
is also appropriate. Should the voltage supply of the electric
drives fail, both an emergency braking and an emergency release
function of the vehicle brake can be achieved via manual operation.
In order to simplify an emergency release function of this kind and
as a low-budget application, the operating device of the lever 128
may be mechanically coupled to the second mobile stop 120, so that
the second mobile stop 120 is also moved when the lever 128 moves
and the lever arrangement 102 is allowed to move into the parking
brake position. This coupling may be effected mechanically via an
additional transmission, so that an increased force can be applied
to the second mobile stop 120 when changing the lever arrangement
102 over from the parking brake position to the service brake
region.
[0029] According to the embodiments presented above, the lever
arrangement 102 can be moved by means of the drive 100, the mobile
stop 120 or the operating device of the lever 128 from the service
brake region into the parking brake position or from the parking
brake position into the service brake region. In order to satisfy
the legal requirements for separate operation of the service brake,
the parking brake and an emergency brake, as well as the emergency
release function of the parking brake, combinations of the
above-mentioned drive and operating means are optionally possible.
When using a plurality of electric drives, it is in particular of
advantage for the electrically controllable actuating device of the
second mobile stop 120 and the electric drives of the operating
device of the lever 128 and the spindle drive 126 to be supplied by
either separate or common voltage sources. This measure also
guarantees redundant implementation of the brake function in a
brake system of the brake-by-wire type.
[0030] The described actuator subassemblies may be used in their
various embodiments within a vehicle brake. It is in particular of
advantage to mount on each wheel brake of at least one axle a
respective actuator subassembly, each of which comprises a lever
128 and which can be jointly operated via an operating device with
the force F.
* * * * *