U.S. patent application number 12/717517 was filed with the patent office on 2010-10-21 for compressed air generator unit for a vehicle and method for the control thereof.
This patent application is currently assigned to KNORR-BREMSE Systeme fuer Nutzfahrzeuge GmbH. Invention is credited to Eduard GERUM.
Application Number | 20100266425 12/717517 |
Document ID | / |
Family ID | 40193688 |
Filed Date | 2010-10-21 |
United States Patent
Application |
20100266425 |
Kind Code |
A1 |
GERUM; Eduard |
October 21, 2010 |
Compressed Air Generator Unit for a Vehicle and Method for the
Control Thereof
Abstract
A compressed air generator system for a vehicle includes at
least one drive motor having a compressed air generator for
generating compressed air, an electrical motor coupled to the
compressed air generator for driving the compressed air generator;
a controllable coupling for coupling the compressed air generator
to the at least one drive motor, a control device for controlling
the compressed air generator unit, and a synchronization device for
synchronizing a compressed air generator rotational speed of the
compressed air generator and an output rotational speed of the at
least one drive motor. The controllable coupling is switchable with
a synchronized compressed air generator rotational speed and output
rotational speed. A corresponding method controls the compressed
air generator system.
Inventors: |
GERUM; Eduard; (Rosenheim,
DE) |
Correspondence
Address: |
CROWELL & MORING LLP;INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
KNORR-BREMSE Systeme fuer
Nutzfahrzeuge GmbH
Muenchen
DE
|
Family ID: |
40193688 |
Appl. No.: |
12/717517 |
Filed: |
March 4, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2008/007206 |
Sep 4, 2008 |
|
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12717517 |
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Current U.S.
Class: |
417/223 ;
417/410.1 |
Current CPC
Class: |
B60T 17/02 20130101 |
Class at
Publication: |
417/223 ;
417/410.1 |
International
Class: |
F04B 49/00 20060101
F04B049/00; F04B 35/04 20060101 F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 6, 2007 |
DE |
10 2007 042 319.7 |
Claims
1. A compressed-air generating system of a commercial vehicle with
at least one drive motor, the system comprising: a compressed-air
generator for generating compressed air; an electric motor
operatively coupled to the compressed-air generator for driving the
compressed-air generator; a controllable clutch operatively
configured to couple the compressed-air generator to said at least
one drive motor; a control device operatively configured to control
the compressed-air generating system; a synchronizing device
operatively configured to synchronize a rotation speed of the
compressed-air generator and an output rotation speed of said at
least one drive motor; and wherein the control device controls said
controllable clutch to be shiftable when the compressed-air
generator rotation speed and the output rotation speed of said at
least one drive motor are synchronized by the synchronization
device.
2. The compressed-air generating system according to claim 1,
wherein the synchronizing device comprises: a first determination
device for determining said rotation speed of the compressed-air
generator; a second determination device for determining said
output rotation speed of said at least one drive motor; a
comparator for comparing the compressed-air generator rotation
speed and the output rotation speed; a control unit for the
electric motor, the control unit being configured to control the
electric motor; and a shifting unit operatively configured for
shifting the controllable clutch when the compressed-air generator
rotation speed and the output rotation speed are synchronized.
3. The compressed-air generating system according to claim 1,
wherein the electric motor control unit is operable to set a
rotation speed of the compressed-air generator and to set idling
and generator modes of the electric motor.
4. The compressed-air generating system according to claim 1,
wherein the controllable clutch is a positively locking, shiftable
clutch.
5. The compressed-air generating system according to claim 4,
wherein the controllable clutch is a dog clutch.
6. The compressed-air generating system according to claim 1,
wherein the controllable clutch is coupled to an output of a drive
train of the commercial vehicle.
7. The compressed-air generating system according to claim 1,
wherein the synchronizing device is incorporated into the control
device.
8. A method for controlling a compressed-air generating system of a
vehicle with at least one drive motor, the method comprising the
acts of: driving a compressed-air generator with an electric motor
in order to generate compressed air; synchronizing a rotation speed
of the compressed-air generator with an output rotation speed of
the at least one drive motor; and shifting a controllable clutch
when the rotation speeds are synchronous, in order to couple the
compressed-air generator to the at least one drive motor in order
to generate the compressed air.
9. The method according to claim 8, wherein the act of
synchronizing comprises the acts of: determining a rotation speed
of the compressed-air generator; determining an output rotation
speed of the at least one drive motor; comparing the determined
rotation speeds and generating a control signal for an electric
motor control unit; and actuating an electric motor by the electric
motor control unit based on the control signal relating to the
output rotation speed of the drive motor for synchronizing the
compressed-air generator rotation speed with the output rotation
speed.
10. The method according to claim 8, wherein the act of shifting
comprises the acts of: engaging the controllable clutch via a
shifting unit; and controlling the electric motor in an idling
state by way of the electric motor control unit.
11. The method according to claim 9, wherein the act of shifting
comprises the acts of: engaging the controllable clutch via a
shifting unit; and controlling the electric motor in an idling
state by way of the electric motor control unit.
12. The method according to claim 8, wherein the act of shifting
comprises the acts of: engaging the controllable clutch via a
shifting unit; and controlling the electric motor in a generator
state by the electric motor control unit in order to generate
electrical energy.
13. The method according to claim 9, wherein the act of shifting
comprises the acts of: engaging the controllable clutch via a
shifting unit; and controlling the electric motor in a generator
state by the electric motor control unit in order to generate
electrical energy.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of PCT International
Application No. PCT/EP2008/007206, filed Sep. 4, 2008, which claims
priority under 35 U.S.C. .sctn.119 from German Patent Application
No. DE 10 2007 042 319.7, filed Sep. 6, 2007, the entire
disclosures of which are herein expressly incorporated by
reference.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] The invention relates to a compressed-air generating system
of a vehicle, and to a method for controlling such a system.
[0003] Compressed-air generating systems of this kind currently
employ compressors and/or compressed-air generators for generating
compressed air, for example for a service brake in a vehicle such
as a commercial vehicle, which are driven exclusively directly by
the drive motor of such a vehicle. In commercial vehicles, the
drive motor is in most cases an internal combustion engine in the
form of a diesel engine. For the purpose of saving energy,
solutions with a mechanical disconnection clutch which is arranged
between the drive and the compressed-air generator are known to the
applicant.
[0004] In the case of vehicles which are equipped with a hybrid
drive, it is necessary for the supply of compressed air to be
ensured even when the drive motor is switched off. Electrically
driven compressed-air generators are used in this case. The drive
is in the form of an electric motor which is equivalent to a
disengaged clutch in the switched-off state, with no power being
lost in this state. However, during normal operation, an electric
motor of this type has a considerable disadvantage since the
conversion of mechanical energy into electrical energy and vice
versa causes energy loss.
[0005] The object of the present invention is therefore to provide
a compressed-air generating system which eliminates or reduces the
above-mentioned disadvantages and exhibits minimal energy
consumption in an electrically driven compressed-air generator.
[0006] The object is achieved by a compressed-air generating system
and method of controlling same, having at least one drive motor. A
compressed-air generator is provided for generating compressed air.
An electric motor, which is coupled to the compressed-air
generator, drives the compressed-air generator. A controllable
clutch couples the compressed-air generator to the at least one
drive motor. A control device controls the compressed-air
generating system, and a synchronizing device synchronizes a
rotation speed of the compressed-air generator and an output
rotation speed of the at least one drive motor. The controllable
clutch is shiftable when the compressed-air generator rotation
speed and the output rotation speed are synchronized.
[0007] According to the invention, it is possible to also drive a
compressed-air generator, which is driven by an electric motor, by
a drive motor of the vehicle via a disconnection clutch or
controllable clutch. The clutch is engaged only when the
compressed-air generator is accelerated by the electric motor to an
output rotation speed of the drive motor of the vehicle or has been
synchronized with the output rotation speed.
[0008] This therefore has the advantageous effect that the energy
consumption for generating compressed air in a compressed-air
generator with an electric drive is reduced, since the electric
motor is switched to an idling state as soon as the compressed-air
generator is driven by the drive motor, so that no further losses
arise.
[0009] Synchronization of the rotation speed of the compressed-air
generator with the output rotation speed of the drive motor has the
effect that no frictional losses occur when the clutch is engaged.
As a result, the maintenance intervals for a friction clutch are
advantageously extended.
[0010] A method according to the invention for controlling a
compressed-air generating system of a vehicle with at least one
drive motor includes the following method steps:
[0011] (V1) driving a compressed-air generator with an electric
motor in order to generate compressed air;
[0012] (V2) synchronizing a rotation speed of the compressed-air
generator with an output rotation speed of the at least one drive
motor; and
[0013] (V3) shifting a controllable clutch when the rotation speeds
are synchronous, in order to couple the compressed-air generator to
the drive motor in order to generate compressed air.
[0014] Without this synchronization, a friction clutch would have
to be designed to be very sturdy since the compressed-air generator
exhibits high peak torques. In a preferred embodiment, provision is
made for the controllable clutch to be in the form of a positively
locking shiftable clutch. This permits an advantageously simple
configuration of a shift clutch with high transmission torques.
This positively locking shiftable clutch may be, for example, a
bolt clutch or a toothed clutch. A particularly robust design is
possible particularly when this shift clutch is a dog clutch.
[0015] In a further embodiment, the synchronization device is
provided with: a first determination device for determining the
rotation speed of the compressed-air generator; a second
determination device for determining the output rotation speed of
the at least one drive motor; a comparison device for comparing the
compressed-air generator rotation speed and the output rotation
speed; an electric motor control unit for controlling the electric
motor; and a shifting unit for shifting the controllable clutch
when the compressed-air generator rotation speed and the output
rotation speed are synchronized.
[0016] Measurement signals and information relating to the rotation
speeds of the drive motor and/or of an output of the drive motor,
for example on a gear mechanism of a drive train of the vehicle,
which are already present in the vehicle can advantageously be used
in this case. The electric motor control unit may use, for example,
rotation speed signals of the electric motor from its own rotation
speed sensors, in order to determine the compressed-air generator
rotation speed. Therefore, the shift clutch can be subjected to
intelligent control in order to always ensure reliable switching on
of the compressed-air generator when compressed-air is required.
The control device may also report information which is important
for the driver of the vehicle and display such information for
him.
[0017] In a further embodiment, provision is made for the electric
motor control unit to be designed to set the compressed-air
generator rotation speed, and to set an idling mode and a generator
mode of the electric motor. When the drive motor of the vehicle
drives the compressed-air generator when the shift clutch is
engaged, the electric motor is switched to an idling state. That is
to say it forms only a low rotation resistance in its bearings and
co-rotates freely. However, in another embodiment, it is also
possible for the electric motor to be switched to a generator
state, that is to say the electric motor can serve as an additional
power source in this case and, for example, charge the vehicle
battery or operate as an emergency power source.
[0018] In a further embodiment, the controllable clutch is coupled
to an output of a drive train of the vehicle. This may be, for
example, on a gear mechanism of the drive train of the vehicle. As
a result, it is possible for a drive torque for the compressed-air
generator to be produced by the wheels of the vehicle in a manner
driven by way of the drive train even when the motor is switched
off or at a low drive motor rotation speed when the vehicle is
coasting.
[0019] In a further embodiment, the synchronizing device is a
constituent part of the control device, as a result of which space
can be saved. In addition, control elements, for example
processors, of the control device can take on the tasks of rotation
speed determination, comparison, etc.
[0020] In a hybrid drive, only the electric motor can drive the
compressed-air generator when the drive motors are switched off,
with the controllable clutch being disengaged.
[0021] Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of one or more preferred embodiments when considered in
conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
[0022] The single FIGURE is a schematic block diagram of an
exemplary embodiment of a compressed-air generating system
according to the invention.
DETAILED DESCRIPTION OF THE DRAWING
[0023] In the single FIGURE, solid lines between functional units
represent a transmission of force, for example by torque
transmission, and dashed lines represent control connections, for
example for control signals and/or measurement signals.
[0024] A vehicle, which is only schematically indicated here, has,
in this example, a hybrid drive with a first drive motor 2, for
example an internal combustion engine in the form of a diesel
engine, and a further drive motor 2' in the form of an electric
motor or machine. These drive motors 2, 2' are coupled to a drive
train 13 which includes a gear mechanism 14 and a drive axle 18, in
which a differential gear mechanism and two wheels are provided. A
motor controller 19 is connected to the drive motors 2, 2' and to
the gear mechanism 14.
[0025] In this example, the gear mechanism 14 is equipped with an
output 15 for coupling to a compressed-air generating system 20 via
a clutch drive KA, for example a shaft.
[0026] The compressed-air generating system 20 has a compressed-air
generator 1 or compressor, which is coupled to an electric motor 3
and to a controllable clutch 4, and a control device 5 for
controlling the compressed-air generating system 20. The
compressed-air generator 1 draws in intake air AL during operation,
compresses this intake air and conveys it as compressed air DL to a
compressed-air reservoir 7, from which the compressed air DL is
taken as required, for example for a brake system of a commercial
vehicle.
[0027] The control device 5 has a synchronizing device 6 with a
first determination device 8 for a compressed-air generator
rotation speed d1, a second determination device 9 for an output
rotation speed d2 of the drive motor 2, 2' (in this case the output
15), a comparison device 10, an electric motor control unit 11 and
a shifting unit 12.
[0028] The control device 5 is also coupled with pressure sensors
16 for detecting a pressure of the intake air AL at the
compressed-air generator 1 and a pressure of the compressed air DL
(either at the compressed-air generator 1 or at the compressed-air
reservoir 7). Rotation speed sensors 17 on a coupling shaft between
the electric motor 3 and the compressed-air generator 1 and on a
coupling shaft between the compressed-air generator 1 and the
controllable clutch 4 are likewise coupled to the control device 5
and transmit measurement signals of the associated rotation speeds.
The electric motor 3 can be equipped with an integrated rotation
speed sensor, (indicated by a branched control path). The control
unit 5 is also coupled to the controllable clutch 4 and to the
motor controller 19.
[0029] The functioning of the individual functional units of the
compressed-air generating system 20 is described below. One of the
drive motors 2, 2' is in operation. The controllable clutch 4 is
initially disengaged. When compressed air is required in the
compressed-air reservoir 7, the first determination device 8
determines the output rotation speed d2 of the drive motor 2, 2'
via the connection to the motor controller 19. The second
determination device 9 determines the rotation speed d1 of the
compressed-air generator 1. The comparison device 10 compares the
rotation speeds d1 and d2. When there is a difference, the
comparison device generates a signal for the electric motor control
unit 11 which drives the electric motor 1 and sets it to a rotation
speed d1 corresponding to the output rotation speed d2, that is to
say it is synchronized with this. The shifting unit 12 then
connects the controllable clutch 4, that is to say the controllable
clutch is engaged and couples the drive motor 2, 2' to the
compressed-air generator 1 via the output 15 and the gear mechanism
14. The drive motor 2, 2' now drives the compressed-air generator 1
and the electric motor 3 is switched to an idling state by the
electric motor control unit 11.
[0030] If the drive motor 2, 2' is not in operation and pressure is
required, only the electric motor 3 is switched on and drives the
compressed-air generator 1.
[0031] Synchronization of the rotation speeds d1 and d2 makes it
possible for the controllable clutch 4 to be designed with a robust
configuration as a shiftable positively locking clutch. This may
be, for example, a dog clutch, a toothed clutch or a bolt clutch
with an electric drive.
[0032] It is therefore also possible to use a friction clutch or a
combination including a dog clutch and a friction clutch, for
example as a kind of synchronizer ring.
[0033] The control device 5 can also have a signalling device
which, for example, provides information for the driver. This may
be, for example, a fault message, maintenance message, etc.
TABLE-US-00001 Table of Reference Numerals 1 Compressed-air
generator 2, 2' Drive motor 3 Electric motor 4 Clutch 5 Control
device 6 Synchronizing device 7 Compressed-air reservoir 8 First
determination device 9 Second determination device 10 Comparison
device 11 Electric motor control unit 12 Shifting unit 13 Drive
train 14 Gear mechanism 15 Output 16 Pressure sensor 17 Rotation
speed sensor 18 Drive axle 19 Motor controller 20 Compressed-air
generating system AL Intake air DL Compressed air d1 Compressed-air
generator rotation speed d2 Output rotation speed KA Clutch
drive
[0034] The foregoing disclosure has been set forth merely to
illustrate the invention and is not intended to be limiting. Since
modifications of the disclosed embodiments incorporating the spirit
and substance of the invention may occur to persons skilled in the
art, the invention should be construed to include everything within
the scope of the appended claims and equivalents thereof.
* * * * *