U.S. patent application number 09/760207 was filed with the patent office on 2001-08-09 for arrangement for producing a vacuum in a motor vehicle system.
Invention is credited to Hagen, Aurel, Klein, Peter, Mauz, Lothar, Pradt, Arthur, Schweizer, Bernhard, Wunderlich, Klaus.
Application Number | 20010011456 09/760207 |
Document ID | / |
Family ID | 7627327 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010011456 |
Kind Code |
A1 |
Hagen, Aurel ; et
al. |
August 9, 2001 |
Arrangement for producing a vacuum in a motor vehicle system
Abstract
In an arrangement for producing a vacuum in a motor vehicle
system including an internal combustion engine with an air intake
system, a vacuum-operated power brake system for braking the
vehicle and a fuel vapor adsorption system for collecting fuel
vapors, a vacuum pump is provided which has a suction side in
communication selectively with the vacuum operated power brake
system and the fuel vapor adsorption system and a discharge side in
communication with the air intake system of the internal combustion
engine.
Inventors: |
Hagen, Aurel; (Stuttgart,
DE) ; Klein, Peter; (Stuttgart, DE) ; Mauz,
Lothar; (Esslingen, DE) ; Pradt, Arthur;
(Herrenberg, DE) ; Schweizer, Bernhard; (Eutingen,
DE) ; Wunderlich, Klaus; (Waiblingen, DE) |
Correspondence
Address: |
Klaus J. Bach
4407 Twin Oaks Drive
Murrysville
PA
15668
US
|
Family ID: |
7627327 |
Appl. No.: |
09/760207 |
Filed: |
January 12, 2001 |
Current U.S.
Class: |
60/397 ; 123/520;
188/356 |
Current CPC
Class: |
B60T 17/02 20130101;
F02M 25/089 20130101; B60T 13/46 20130101 |
Class at
Publication: |
60/397 ; 123/520;
188/356 |
International
Class: |
F02M 025/07; F16D
065/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 13, 2000 |
DE |
100 01 060.1 |
Claims
What is claimed is:
1. An arrangement for producing a vacuum in a motor vehicle system
including an internal combustion engine with an air intake system,
a vacuum operated power brake system for braking said vehicle, a
fuel vapor adsorption system for collecting fuel vapors and a pump
having a suction side in communication selectively by a power brake
vacuum line with said vacuum-operated power brake system and by a
regeneration line with said fuel vapor adsorption system, and a
discharge side in communication by a delivery line with the air
intake system of said internal combustion engine.
2. An arrangement according to claim 1, wherein said pump is in
electric motor driven suction pump.
3. An arrangement according to claim 1, wherein said pump is driven
by said internal combustion engine and a separating clutch is
provided which can be activated electromagnetically.
4. An arrangement according to claim 1, wherein said pump is an
enclosed, explosion-protected diaphragm pump.
5. An arrangement according to claim 1, wherein said fuel vapor
adsorption system includes an activated-carbon canister provided
with HC-sensors which are connected, by signal lines, to an
electronic control unit.
6. An arrangement according to claim 5, wherein said power brake
system includes an electronic control unit, and a vacuum pressure
sensor is provided in said power brake system and is connected, via
a signal line, to said electronic control unit.
7. An arrangement according to claim 6, wherein said electronic
control unit is integrated in an electronic engine-control unit of
said internal combustion engine.
8. An arrangement according to claim 1, wherein a changeover valve
is provided between the diaphragm pump section side and the fuel
adsorption system and the power brake system for selectively
connecting said power brake system and said fuel adsorption system
to the pump section side, said changeover valve being a 3/2-port
directional control valve, which is spring-biased to a position
providing for the connection of said power brake system to said
pump suction side.
9. An arrangement according to claim 7, wherein a regenerating line
extends between said 3/2-port directional control valve and said
fuel adsorption system, said regenerating line including a pulsed
fuel-tank vent valve for controlling the regeneration air flow
volume to said engine.
10. An arrangement according to claim 9, wherein said 3/2-port
directional control valve and said fuel-tank vent valve are
connected via signal lines to said electronic control unit and said
electronic engine-control unit.
11. An arrangement according to claim 1, wherein a first non-return
valve is arranged in a vacuum line extending between said 3/2-port
directional control valve and said power brake system.
12. An arrangement according to claim 1, wherein a throttle element
is provided in the intake system for regulating the amount of air
supplied to said internal combustion engine and said delivery line
between said diaphragm pump and said intake system is connected to
said intake system upstream of an intake air throttle element
disposed in the engine air intake duct.
13. An arrangement according to claim 12, wherein a further vacuum
line extends between the air intake duct downstream of said
throttle element and the power brake system and a second non-return
valve is provided in said further vacuum line.
14. Method of controlling the arrangement for producing a vacuum
according to claim 1, wherein, with a vacuum less than a
predetermined value present in the power brake system, the 3/2-port
directional control valve is switched in such a manner that the
diaphragm pump suction side and the power brake system are in
communication and the vacuum pump is operated.
15. A method according to claim 14, wherein the fuel-tank vent
valve is activated via a pulse-width-modulated activating signal of
the control unit as a function of engine load and a predetermined
charge of the fuel vapor adsorption system when a vacuum is present
in said regeneration line.
Description
[0001] The invention relates to an arrangement for producing a
vacuum in a motor vehicle system including a pump, which is
connected, with its suction side, to a pneumatic power brake system
for generating a vacuum in the power brake system.
[0002] It is known in practice that diesel engines are provided
with vacuum pumps, which are connected with their suction side to a
power brake system in order to produce the vacuum required for its
operation. Air taken in from the latter is discharged to the
surroundings. Vacuum pumps are needed because diesel engines are
operated essentially without the throttle elements, which are
provided in the intake ducts of spark-ignition engines. Therefore,
in contrast to conventional spark-ignition engines, negative
pressure, that is a vacuum, which can be used for operating the
power brake systems, is not produced in the intake duct of a diesel
engine.
[0003] In the case of conventional spark-ignition engines, the
airflow to the engine cylinders is restricted in accordance with
the amount of fuel injected by a throttle valve arranged in the
intake duct. During partial-load operation of the spark-ignition
engine, the throttle valve position is controlled to the extent
that the cross-section constriction in the intake duct causes the
cylinders to have a correspondingly smaller filling. This results
in a negative pressure in the suction manifold downstream of the
throttle valve. The negative pressure is used in spark-ignition
engines for the evacuation of a vacuum reservoir for the power
brake system.
[0004] Moreover, this vacuum is used in the prior art for the
regeneration of a fuel-vapor adsorption system. The vacuum in the
intake region is employed to generate a scavenging airflow through
the activated-carbon canister.
[0005] To meet exhaust-emission regulations, warm-up procedures
require that modern engines are driven with retarded ignition and
increased idling speed. Also, the power consumed and the friction
generated by additional equipment increase the load on the engine.
As a result, the throttle valve has to be opened relatively wide
during engine warm-up so that the vacuum available during this
operating period is very small.
[0006] With further efficiency-increasing measures in the
spark-ignition engine for a reduction of the consumption, the
throttling means may even be fully replaced by controlled direct
fuel injection with throttle-free load control and variable inlet
valve operation. In these engine concepts, virtually no usable
vacuum will be generated in the intake duct, i.e. the intake duct
serves exclusively for the supply of air to the cylinders.
[0007] This means that, in the new engine concepts, either the
throttle valve is omitted or it is largely ineffective for
producing a vacuum.
[0008] As a result, a vacuum sufficient for operating power brake
systems can no longer be generated in the intake duct.
[0009] For this reason, even in motor vehicles having
spark-ignition engines, the vacuum is produced sometimes by
providing a suction pump as it is done in connection with diesel
engines, in order to permit operation of the power brake system.
Systems of this type are disclosed in DE-A 2 347 701 and WO
93/11983.
[0010] However, it has so far not been possible in any of the
above-described systems to satisfactorily use the pump in
connection with the fuel-vapor-retaining systems arranged in motor
vehicles.
[0011] The object of the present invention is to provide an
arrangement with which a power brake system and a fuel-retaining
(fuel vapor adsorption) system can be operated by a vacuum
generated by a pump wherein, at the same time, the fuel consumption
is reduced and the amount of pollutants emitted are minimized.
SUMMARY OF THE INVENTION
[0012] In an arrangement for producing a vacuum in a motor vehicle
system including an internal combustion engine with an air intake
system, a vacuum-operated power brake system for braking the
vehicle and a fuel vapor adsorption system for collecting fuel
vapors, a vacuum pump is provided which has a suction side in
communication selectively with the vacuum operated power brake
system and the fuel vapor adsorption system and a discharge side in
communication with the air intake system of the internal combustion
engine.
[0013] With the arrangement according to the invention, a vacuum
can be produced which is sufficient and always available for the
operation of a power brake system and which is available over the
entire operating range of an internal combustion engine. Moreover,
efficient regeneration of a fuel-vapor-retaining system is made
possible.
[0014] Such a fuel-vapor-adsorption system can also be operated in
the high load range or in the full load range of the engine. During
high load operation, a high air mass flow is supplied to the engine
so that a very efficient regeneration is possible. At the same
time, the conversion of the fuel vapors in the engine is
particularly effective because of better engine charge conditions.
Also, with conventional throttle-controlled engines an insufficient
vacuum is generated during high load engine operation for proper
braking operation or for a proper regeneration of the fuel vapor
adsorber.
[0015] The activation of the power-brake system and the
regeneration of the fuel vapor adsorber system can be achieved with
a single pump. The air flow or air/fuel-vapor flow generated by the
pump is introduced into the intake system of the internal
combustion engine.
[0016] Further advantages and embodiments of the invention will
become apparent from the following description of the invention
based on the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
[0017] The single FIGURE shows a circuit diagram of an arrangement
for producing a vacuum in a motor vehicle in accordance with the
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0018] An arrangement 1 for producing a vacuum in a motor-vehicle
system comprises a pump 2, which is connected at its suction side,
via a line arrangement 3, to a pneumatic power brake system 4. In
addition, an activated-carbon canister 5 of a fuel-vapor-adsorbing
system 6, which is known per se and is in communication with a fuel
tank 27, is connected to the line arrangement 3 at the suction side
of the pump 2. The pump 2 is connected at its delivery side to an
air-intake system 7 of an internal combustion engine 8.
[0019] The pump 2 is a suction pump driven preferably by an
electric motor 9. An encapsulated explosion-protected diaphragm
pump 2 has been found to be particularly advantageous, since a
diaphragm pump has no leakages and, at a high vacuum without gas
flow, consumes only a small amount of power because the gas in the
pump chamber acts as a pneumatic spring.
[0020] In another embodiment, the pump may be driven by the
internal combustion engine via an electromagnetic clutch.
[0021] During operation of the arrangement 1, an explosive fuel/air
mixture is pumped by the diaphragm pump 2 from the activated-carbon
canister 5 to the engine intake duct 7. The diaphragm pump 2
functions in a similar manner as a rubber-bellow system. It is not
subject to leakage. No fuel/air mixture flowing from the
activated-carbon canister 5 can escape into the surroundings on the
suction side of the diaphragm pump 2. The same is true for the
delivery side, since the fuel/air mixture conducted on this side of
the diaphragm pump 2 is conveyed through the leak-proof line 23 to
the intake system 7 and passes from there directly into the
internal combustion engine 8, where it is combusted. The engine
shown here is a spark-ignition engine.
[0022] In contrast to other pumps, the diaphragm pump 2 does not
have a shaft extending through a housing wall so that no medium can
escape. Such a pump has therefore exceptional explosion-proof
properties.
[0023] The activated-carbon canister 5 is provided with HC sensors
10, which are connected to an electronic control unit 13 via signal
lines 11. The HC-sensors 10 are provided for determining the charge
of the activated carbon canister 5. The values determined are
transmitted continuously to an electronic motor-control unit 13,
which can be a conventional engine-control unit.
[0024] The power brake system 4 is provided with a pressure sensor
14, which is connected to the electronic control unit 12 via a
signal line 15 and which determines the pressure present in the
power brake system 4. This value is transmitted to the control unit
12 via the signal line 15.
[0025] In the present exemplary embodiment, the electronic control
unit 12 is designed as a separate component of the device 1.
However, it is of course within an expert's discretion to integrate
the electronic control unit 12 in a control unit, which is already
present in the motor vehicle. This may be for example the
electronic engine-control unit 13 of the internal combustion engine
8.
[0026] A change-over valve designed as a spring-resetting 3/2-port
directional control valve 16 is arranged between the diaphragm pump
2, the activated-carbon canister 5 and the power brake system 4.
Depending on its switching position, communication is established,
via the line system 3, between the diaphragm pump 2 and the power
brake system 4 or, by way of a line 17, between the pump 2 and the
activated-carbon canister 5.
[0027] The regenerating line 17 includes a pulsed fuel tank vent
valve 18 and extends between the 3/2-port directional control valve
16 and the activated-carbon canister 5. The 3/2-port directional
control valve 16 and the fuel-tank vent valve 18 are in
communication with the electronic control unit 12 and the
electronic engine-control unit 13 via signal lines 19, 20, 21.
[0028] In order to ensure reliable operation, a first non-return
valve 22 is arranged in the line 3 between the 3/2-port directional
control valve 16 and the power brake system 4. If the diaphragm
pump 2 breaks down, air is therefore prevented from flowing into
the power brake system 4, and a vacuum present in the power brake
system 4 can be maintained.
[0029] A throttle element (which is not illustrated as it is known
per se) for controlling the amount of air supplied to the internal
combustion engine 8 is provided in the intake system 7. A line 23
extends from the diaphragm pump 2 to the intake system 7 and is
connected thereto upstream of the throttle element, in the
direction of intake air flow. This arrangement ensures that the air
evacuated from the power brake system 4 and the air/fuel vapor
mixture from the activated-carbon canister are introduced into the
intake air duct upstream of the throttle element or the throttle
valve. In this way, introduction of air and air/fuel mixture into
the intake pipe, which may be evacuated downstream of the throttle
valve is avoided so that the throttling of the internal combustion
engine 8 cannot be circumvented. The outlay for the control
arrangement of the engine is therefore not increased.
[0030] A further line 24 of the line system 3 is provided between
the intake system 7 and the power brake system 4. The further line
24 is connected to the intake manifold 25 of the intake system 7
downstream of the throttle element. The further line 24 permits a
vacuum produced by a throttle element in the intake system 7 to be
used additionally for the evacuation of the power brake system 4.
However, the vacuum is only applied if it is greater than the
vacuum, which can be produced by the electric pump motor 9. The
pump motor 9 is switched on by the control unit 22 when the vacuum
in the power brake system becomes less than a predetermined value
sufficient to safely operate the power brakes.
[0031] In order to avoid a back-flow of air/fuel mixture from the
intake system 7 into the power brake system 4, a second non-return
valve 26 is provided in the further line 24.
[0032] During operation of the engine, the diaphragm pump 2 is
switched on as a function of the charge of the activated carbon
canister 5 and/or of the negative pressure (vacuum) state of the
power brake system 4. However, in this case the vacuum requirement
of the power brake system 4 is the principal parameter for the
electronic control unit 12 because of vehicle safety consideration.
This means that, when a pressure above a desired negative pressure
is present in the power-brake system 4 that is the vacuum is less
than the predetermined value, the 3/2-port directional control
valve 16 is switched in such a manner that the diaphragm pump 2 and
the power brake system 4 are in line connection and the latter is
evacuated by the diaphragm pump 2.
[0033] The switching of the 3/2-port directional control valve 16
takes place via the electronic control unit 12 at an appropriate
signal from the pressure sensor 14. For this action, the 3/2-port
directional control valve 16 is de-energized so that, in this rest
position of the 3/2-port directional control valve 16, the suction
side of the diaphragm pump 2 is connected to the power brake system
4. It is therefore ensured that the valve 16 is spring-biased to a
position in which the vacuum for the power brake system 4 is
provided when there is an electrical line interruption to the
3/2-port directional control valve 16.
[0034] The fuel adsorbing system 6 is regenerated by switching of
the 3/2-port directional control valve 16 depending on need.
However, the valve 16 can be switched over only when the power
brake system 4 has a vacuum supply sufficient for safe operation of
the brakes.
[0035] The activated carbon canister 5 is regenerated depending on
charge sensing means 10 disposed in the activated-carbon canister
5. For this purpose, the diaphragm pump 2 is activated and the
3/2-port directional control valve 16 is energized, whereby the
connection between the diaphragm pump 2 and the activated-carbon
canister 5 is established. As a result, an additional air/fuel
mixture is supplied to the internal combustion engine 8 resulting
in a change of the lambda value of the exhaust gas. Based on the
lambda value change, the regeneration procedure of the
activated-carbon canister 5 is controlled by the control unit 12
and the engine-control unit by a pulsing of the fuel-tank vent
valve 18.
[0036] To ensure that the pump is switched on as much as possible
only when needed particularly in order to keep the power
consumption and the wear of the diaphragm pump 2 to a minimum, the
charge of the activated carbon canister 5 is evaluated by
evaluation electronics of the electronic control unit 12 using the
signals from the HC-sensors 10 in the activated-carbon canister 5.
Depending on this evaluation, the diaphragm pump 2 is switched on
as required in order to regenerate the fuel-adsorbing system 6.
[0037] The fuel-tank vent valve 18 is activated by a
pulse-width-modulated activating signal of the electronic unit 12,
depending on the engine load and engine speed, when there is a
sufficiently large vacuum in the regenerating line 17 and the
activated-carbon canister 5 has a sufficiently large charge to
justify regeneration.
[0038] Since with the pump 2 a virtually constant vacuum level is
available, there is a precisely determinable characteristic curve
available for controlling the flow volume through the fuel-tank
vent valve 18 as a function of the activating signal. As a result,
the flow control is greatly simplified and the maximum allowable
regenerating flow volume can be supplied to the engine so that
operation of the pump is generally necessary only for short
periods.
[0039] The fuel-tank vent valve 18 is a valve, which can merely be
opened and closed. Its opening cross-section cannot be varied. In
order to control the flow volume from the activated-carbon canister
5 to the internal combustion engine 8, it is necessary to provide a
flow cross-section corresponding to the operating state of the
internal combustion engine 8 and the state of the adsorbing system
6. Since, however, the fuel-tank vent valve 18 can only be
completely opened or closed, the opening and closing of the
fuel-tank vent valve 18 is pulsed in order to simulate a variable
opening cross-section.
[0040] The pulsing of the fuel-tank vent valve 18 takes place via
the pulse-width-modulated signal of the control unit 12, which may,
for example, be a square-wave signal recurring at a frequency of 10
Hz. The pulse width of the signal determines the energizing
duration and therefore also the opening duration of the fuel-tank
vent valve 18. Different pulse widths are therefore used to obtain
different opening durations simulating a variable cross section of
the fuel-tank vent valve 18.
[0041] When the activated-carbon canister 5 is fully charged, the
fuel-tank vent valve 18 is operated at a very small pulse ratio.
When the activated-carbon canister 5 has a small charge, the
fuel-tank vent valve 18 is operated at a large pulse ratio. Since a
vacuum is constantly provided by the diaphragm pump 2, the pulse
ratio depends on the charge of the activated-carbon canister 5 and
on the air mass flow through the internal combustion engine 8.
[0042] The arrangement for producing a vacuum in a motor vehicle
system is particularly suitable for use in connection with
spark-ignition engines. However, it may, of course, also be used in
diesel engines or other internal combustion engines, specifically
whenever a power brake system and a fuel adsorption system are to
be supplied with a sufficient operating vacuum.
* * * * *