WO2002090163A2 - Hydraulic vehicle retarder and method of controlling such retarder - Google Patents

Hydraulic vehicle retarder and method of controlling such retarder Download PDF

Info

Publication number
WO2002090163A2
WO2002090163A2 PCT/SE2002/000878 SE0200878W WO02090163A2 WO 2002090163 A2 WO2002090163 A2 WO 2002090163A2 SE 0200878 W SE0200878 W SE 0200878W WO 02090163 A2 WO02090163 A2 WO 02090163A2
Authority
WO
WIPO (PCT)
Prior art keywords
proportional valve
control unit
retarder
pressure
air pressure
Prior art date
Application number
PCT/SE2002/000878
Other languages
French (fr)
Other versions
WO2002090163A3 (en
Inventor
Marcus STEÉN
Bengt Samuelsson
Original Assignee
Volvo Lastvagnar Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Volvo Lastvagnar Ab filed Critical Volvo Lastvagnar Ab
Publication of WO2002090163A2 publication Critical patent/WO2002090163A2/en
Publication of WO2002090163A3 publication Critical patent/WO2002090163A3/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T10/00—Control or regulation for continuous braking making use of fluid or powdered medium, e.g. for use when descending a long slope
    • B60T10/02—Control or regulation for continuous braking making use of fluid or powdered medium, e.g. for use when descending a long slope with hydrodynamic brake

Definitions

  • Hydraulic vehicle retarder and method of controlling such retarder
  • the present invention relates to a hydraulic retarder installation for motor vehicles, comprising a stator solidly mounted in a housing, a rotor rotatably mounted in the housing, a reservoir for hydraulic fluid, an electrically operated proportional valve in a compressed air connection between a source of compressed air and the reservoir, an electronic control unit, which controls the proportional valve as a function of signals from a brake control, and an air pressure sensor, which sends a signal to the control unit dependent on the air pressure on the outlet side of the proportional valve.
  • the invention also relates to a method of controlling the braking torque form such a hydraulic retarder installation.
  • Retarder installations known up to now of this type have control units which, in response to a signal to activate the retarder to apply a certain braking torque, initially apply a current over the solenoid of the proportional valve, which is estimated to provide an air pressure corresponding to the requested braking torque.
  • the control unit In order to obtain a rapid response, i.e. a rapid increase in pressure, the control unit initially directs an electric current of higher magnitude than what is required to maintain the de- sired braking torque. The air pressure feeds back the current value of the pressure obtained, and the control unit then corrects the electrical control current so that the current value of the pressure is adjusted towards a predetermined pressure, which corresponds to the requested braking torque.
  • the braking torque which is initially obtained upon activation of the retarder will vary between different retarder installations. At one extreme the torque will be substantially higher than what is desired. Gradually the retardation is eased to the desired level by feeding back the pressure to the control unit. At the other extreme, the torque will be substantially lower than that desired, which will instead result in the initial retardation being lower than what is desired. The retardation will then gradually increase to the desired level by feed-back of the pressure to the control unit.
  • the purpose of the present invention is to achieve a hydraulic retarder installation of the type described by way of introduction, through which variations in the reaction between the different proportional valves can be compensated so that the braking torque upon activation of the retarder can be controlled more rapidly towards the requested torque.
  • control unit there are stored command values of the pressure on the outlet side of the proportional valve at a number of levels and values of the electric current through the proportional valve at said pressure levels and that the control unit is arranged, upon actuation of the brake control for activating the retarder, through utilization of the stored electric current values and feed-back of the measured air pressure on the outlet side of the proportional valve to control the proportional valve towards a pressure corresponding to the requested braking torque.
  • the control unit is activated according to the invention, under stationary conditions, both as regards the control- ling of the proportional valve by the control unit and the signal from the air pressure sensor to the control unit to read and store various connected values of pressure and electric current strengths and upon activation of the retarder said connected values are utilized to control the proportional valve towards a pressure corresponding to the requested braking torque.
  • the same response is obtained in different retarder installations re- gardless of the spreading and the difference in reaction between the different proportional valves.
  • Fig. 1 shows a schematic perspective view of a known hydraulic retarder
  • Fig. 2 shows a schematic diagram of one embodiment of a re- tarder installation according to the invention
  • Fig. 3 is a diagram of the response of the proportional valve in a known retarder installation upon activation of the retarder
  • Fig. 4 is a corresponding diagram of the reaction of the proportional valve in a retarder installation according to the invention
  • Fig. 5 is a calibration diagram.
  • the retarder 1 shown in Fig. 1 is a hydraulic retarder which is known per se and comprises a housing 2 with a stator 3 arranged solidly in the housing and a rotatably mounted rotor 4, which is connected, in a manner not shown in more detail here, to the output shaft of the vehicle gearbox and thus also to the vehicle propeller shaft 5.
  • the retarder 1 has a tank 6 for hydraulic fluid and a cooler 7 for cooling the fluid.
  • the retarder 1 is controlled by an electronic control unit (control computer) 8, which can be the same unit as that controlling the various functions of the engine, the clutch and the transmission.
  • the control unit 8 controls a regulator valve in the form of an electrically operated proportional valve 9, which is coupled between a compressed air source (accumulator tank) 10 and the hydraulic fluid tank 6 of the retarder 1.
  • a compressed air source accumulator tank
  • the hydraulic fluid tank 6 of the retarder 1 When compressed air is supplied to the tank 6, fluid is pressed in between the rotor 4 and the stator 3 of the retarder, thus gene-rating braking torque, the magnitude of which is dependent on the volume of the fluid which is pressed by the com- pressed air into the chamber in which the rotor rotates.
  • the magnitude of the fluid volume is dependent on the pressure of the compressed air supplied to the tank 6, and this pressure is determined by the setting of the proportional valve 9. This setting is in turn determined by the strength of the electric current which the control unit 8 sends to the solenoid of proportional valve 9.
  • a brake control 11 which can be a separate retarder control or the ordinary brake pedal of the vehicle.
  • the control 11 sends a signal to the control unit 8 representing the braking torque requested by the driver.
  • the control unit 8 then sends out a predetermined current depending on the requested braking torque. Manufacturing tolerances, resulting in a certain variation as regards the setting of the proportional valve 9 and thus the pressure which determines the braking torque, cause in this case variations in the initial braking torque between different retarder installations having identically program-med control units 8.
  • the control unit 8 provides initially an electric current I is accordance with a regulator algorithm, designed in a known manner.
  • a regulator algorithm designed in a known manner.
  • the control unit 8 adjusts the electric current to the value I f , which provides the value of the pressure corresponding to the command value corresponding to the requested braking torque. Since the final level I f of the electric current is not initially known, normally there is always an oscillation sequence, which results in poorer braking torque during the oscillating approach sequence.
  • Fig. 4 shows corresponding electric current and pressure curves for a hydraulic retarder installation with a control unit 8 in which there are stored , according to the invention, the command values of the pressure p on the outlet side of the proportional valve 9 at a number of levels and the electric current I through the valve at these pressure levels.
  • the air pressure p and the corresponding current I are measured and stored in the control unit for later use in compouting I f .
  • a number of different air pres- sures p and corresponding electric surrents I can be measured and stored in the control unit 8 to increase the performance of the retarder installatino for differrent requested braking torques. This is illustrated in the diagram in Fig. 5.
  • the control unit 8 In order to obtain a more rapid and more even build up of torque towards the requested torque, the control unit 8 initially sends out an electric current I consisting of I f calculated from the calibration data together with a supplement ⁇ I from a regulator algorithm.
  • the supplement ⁇ I is initially required during the period from t 0 to t 2 to accelerate the buildup of torque, while I f is used in the stationary condition after the time t 2 , where ⁇ I can be zero, when that calibration data is entirely adapted to the retarderinstallation. Since the final level I f of the electric current is known from the start, there is normally no oscillation approach.

Abstract

Hydraulic retarder installation with a retarder which is controlled by an electronic control unit (8), which regulates, via an electrically operated proportional valve (9), the air pressure in a hydraulic fluid reservoir (6), said pressure determining the braking torque. In the control unit there are stores command values of the pressure at a number of levels and values of the electric current through the valve at these levels. The control unit is disposed, upon activation of the retarder, by utilizing the stored electric current values and feed back of the measured air pressure on the outlet side of the proportional valve, to control the valve towards a pressure, which corresponds in turn to the requested braking torque.

Description

Hydraulic vehicle retarder and method of controlling such retarder
The present invention relates to a hydraulic retarder installation for motor vehicles, comprising a stator solidly mounted in a housing, a rotor rotatably mounted in the housing, a reservoir for hydraulic fluid, an electrically operated proportional valve in a compressed air connection between a source of compressed air and the reservoir, an electronic control unit, which controls the proportional valve as a function of signals from a brake control, and an air pressure sensor, which sends a signal to the control unit dependent on the air pressure on the outlet side of the proportional valve.
The invention also relates to a method of controlling the braking torque form such a hydraulic retarder installation.
Retarder installations known up to now of this type have control units which, in response to a signal to activate the retarder to apply a certain braking torque, initially apply a current over the solenoid of the proportional valve, which is estimated to provide an air pressure corresponding to the requested braking torque. In order to obtain a rapid response, i.e. a rapid increase in pressure, the control unit initially directs an electric current of higher magnitude than what is required to maintain the de- sired braking torque. The air pressure feeds back the current value of the pressure obtained, and the control unit then corrects the electrical control current so that the current value of the pressure is adjusted towards a predetermined pressure, which corresponds to the requested braking torque.
Due to tolerances and variations in the characteristics of the valve springs of the proportional valves, the braking torque, which is initially obtained upon activation of the retarder will vary between different retarder installations. At one extreme the torque will be substantially higher than what is desired. Gradually the retardation is eased to the desired level by feeding back the pressure to the control unit. At the other extreme, the torque will be substantially lower than that desired, which will instead result in the initial retardation being lower than what is desired. The retardation will then gradually increase to the desired level by feed-back of the pressure to the control unit.
The purpose of the present invention is to achieve a hydraulic retarder installation of the type described by way of introduction, through which variations in the reaction between the different proportional valves can be compensated so that the braking torque upon activation of the retarder can be controlled more rapidly towards the requested torque.
This is achieved according to the invention by virtue of the fact that in the control unit there are stored command values of the pressure on the outlet side of the proportional valve at a number of levels and values of the electric current through the proportional valve at said pressure levels and that the control unit is arranged, upon actuation of the brake control for activating the retarder, through utilization of the stored electric current values and feed-back of the measured air pressure on the outlet side of the proportional valve to control the proportional valve towards a pressure corresponding to the requested braking torque.
Before the retarder installation is put into operation in the vehicle, the control unit is activated according to the invention, under stationary conditions, both as regards the control- ling of the proportional valve by the control unit and the signal from the air pressure sensor to the control unit to read and store various connected values of pressure and electric current strengths and upon activation of the retarder said connected values are utilized to control the proportional valve towards a pressure corresponding to the requested braking torque. In this way the same response is obtained in different retarder installations re- gardless of the spreading and the difference in reaction between the different proportional valves.
The invention will be described in more detail below with reference to examples shown in the accompanying drawings, where Fig. 1 shows a schematic perspective view of a known hydraulic retarder, Fig. 2 shows a schematic diagram of one embodiment of a re- tarder installation according to the invention, Fig. 3 is a diagram of the response of the proportional valve in a known retarder installation upon activation of the retarder, Fig. 4 is a corresponding diagram of the reaction of the proportional valve in a retarder installation according to the invention and Fig. 5 is a calibration diagram.
The retarder 1 shown in Fig. 1 is a hydraulic retarder which is known per se and comprises a housing 2 with a stator 3 arranged solidly in the housing and a rotatably mounted rotor 4, which is connected, in a manner not shown in more detail here, to the output shaft of the vehicle gearbox and thus also to the vehicle propeller shaft 5. The retarder 1 has a tank 6 for hydraulic fluid and a cooler 7 for cooling the fluid.
As can be seen schematically in Fig. 2, the retarder 1 is controlled by an electronic control unit (control computer) 8, which can be the same unit as that controlling the various functions of the engine, the clutch and the transmission. The control unit 8 controls a regulator valve in the form of an electrically operated proportional valve 9, which is coupled between a compressed air source (accumulator tank) 10 and the hydraulic fluid tank 6 of the retarder 1. When compressed air is supplied to the tank 6, fluid is pressed in between the rotor 4 and the stator 3 of the retarder, thus gene-rating braking torque, the magnitude of which is dependent on the volume of the fluid which is pressed by the com- pressed air into the chamber in which the rotor rotates. The magnitude of the fluid volume is dependent on the pressure of the compressed air supplied to the tank 6, and this pressure is determined by the setting of the proportional valve 9. This setting is in turn determined by the strength of the electric current which the control unit 8 sends to the solenoid of proportional valve 9. When the retarder 1 is to be activated, the driver actuates a brake control 11, which can be a separate retarder control or the ordinary brake pedal of the vehicle. The control 11 sends a signal to the control unit 8 representing the braking torque requested by the driver. The control unit 8 then sends out a predetermined current depending on the requested braking torque. Manufacturing tolerances, resulting in a certain variation as regards the setting of the proportional valve 9 and thus the pressure which determines the braking torque, cause in this case variations in the initial braking torque between different retarder installations having identically program-med control units 8.
In order to obtain a rapid response, i.e. an even and rapid build up of torque towards the requested torque, the control unit 8 provides initially an electric current I is accordance with a regulator algorithm, designed in a known manner. One example is illustrated in Fig. 3. By feedback to the control unit by means of a pressure sensor 12 which senses the value of the pressure, the control unit 8 adjusts the electric current to the value If, which provides the value of the pressure corresponding to the command value corresponding to the requested braking torque. Since the final level If of the electric current is not initially known, normally there is always an oscillation sequence, which results in poorer braking torque during the oscillating approach sequence.
Fig. 4 shows corresponding electric current and pressure curves for a hydraulic retarder installation with a control unit 8 in which there are stored , according to the invention, the command values of the pressure p on the outlet side of the proportional valve 9 at a number of levels and the electric current I through the valve at these pressure levels. Under stationary conditions, the air pressure p and the corresponding current I are measured and stored in the control unit for later use in compouting If. A number of different air pres- sures p and corresponding electric surrents I can be measured and stored in the control unit 8 to increase the performance of the retarder installatino for differrent requested braking torques. This is illustrated in the diagram in Fig. 5. In order to obtain a more rapid and more even build up of torque towards the requested torque, the control unit 8 initially sends out an electric current I consisting of If calculated from the calibration data together with a supplement ΔI from a regulator algorithm. The supplement ΔI is initially required during the period from t0 to t2 to accelerate the buildup of torque, while If is used in the stationary condition after the time t2, where ΔI can be zero, when that calibration data is entirely adapted to the retarderinstallation. Since the final level If of the electric current is known from the start, there is normally no oscillation approach.

Claims

Claims
1. Hydraulic retarder installation for motor vehicles, comprising a retarder (1) with a stator (3) solidly mounted in a housing (2), a rotor (4) rotatably mounted in the housing, a reservoir (6) for hydraulic fluid, and an electrically operated proportional valve (9) in a compressed air connection between a source of compressed air (10) and the reservoir, an electric control unit (8), which controls the proportional valve as a function of signals from a brake control (11), and an air pressure sensor (12), which sends a signal to the control unit dependent on the air pressure on the outlet side of the proportional valve, characterized in that in the control unit (8) there are stored command values (Pn) of the pressure on the outlet side of the proportional valve (9) at a number of levels and values (In) of the electric current through the proportional valve at said pressure levels and that the control unit is arranged, upon actuation of the brake control (11) for activating the retarder (1), through utilization of the stored electric current values and feed-back of the measured air pressure on the outlet side of the proportional valve (9) to control the proportional valve towards a pressure corresponding to the requested braking torque.
2. Method of controlling the braking torque from a hydraulic retarder (1), having a stator (3) solidly mounted in a housing (2), a rotor (4) rotatably mounted in the housing, a reservoir (6) for hydraulic fluid, and an electrically operated proportional valve (9) in a com- pressed air connection between a source of compressed air (10) and the reservoir, an electronic control unit (8), which controls the proportional valve as a function of signals representing braking moment requested by the driver, and an air pressure sensor (12), which sends a signal to the control unit dependent on the air pressure on the outlet side of the proportional valve, characterized in that the control unit (8) is activated under sta- tionary conditions, both as regards the controlling of the proportional valve by the control unit and the signal from the air pressure sensor to the control unit, to read and store various connected values of pressure (pn) and electric current strengths (In) and upon activation of the retarder said connected values are utilized to control the proportional valve (9) towards a pressure corresponding to the requested braking torque.
PCT/SE2002/000878 2001-05-10 2002-05-07 Hydraulic vehicle retarder and method of controlling such retarder WO2002090163A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0101637-7 2001-05-10
SE0101637A SE523147C2 (en) 2001-05-10 2001-05-10 Hydraulic vehicle retarders and ways to control them

Publications (2)

Publication Number Publication Date
WO2002090163A2 true WO2002090163A2 (en) 2002-11-14
WO2002090163A3 WO2002090163A3 (en) 2003-11-27

Family

ID=20284047

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2002/000878 WO2002090163A2 (en) 2001-05-10 2002-05-07 Hydraulic vehicle retarder and method of controlling such retarder

Country Status (2)

Country Link
SE (1) SE523147C2 (en)
WO (1) WO2002090163A2 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4688384A (en) * 1985-04-15 1987-08-25 The Jacobs Manufacturing Company Braking boost pressure modulator and method
US5771997A (en) * 1994-11-26 1998-06-30 Voith Turbo Gmbh Braking system in conjunction with a hydrodynamic retarder, specifically for motor vehicles
DE19848546C1 (en) * 1998-10-22 2000-04-20 Voith Turbo Kg Vehicle hydrodynamic retarder control method provides over-pressure during initial timed interval before reduction to network pressure over second timed interval
EP1063137A2 (en) * 1999-06-25 2000-12-27 Voith Turbo GmbH & Co. KG Valve device for controlling the operation of an hydrodynamic retarder

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4688384A (en) * 1985-04-15 1987-08-25 The Jacobs Manufacturing Company Braking boost pressure modulator and method
US5771997A (en) * 1994-11-26 1998-06-30 Voith Turbo Gmbh Braking system in conjunction with a hydrodynamic retarder, specifically for motor vehicles
DE19848546C1 (en) * 1998-10-22 2000-04-20 Voith Turbo Kg Vehicle hydrodynamic retarder control method provides over-pressure during initial timed interval before reduction to network pressure over second timed interval
EP1063137A2 (en) * 1999-06-25 2000-12-27 Voith Turbo GmbH & Co. KG Valve device for controlling the operation of an hydrodynamic retarder

Also Published As

Publication number Publication date
SE0101637L (en) 2002-11-11
WO2002090163A3 (en) 2003-11-27
SE0101637D0 (en) 2001-05-10
SE523147C2 (en) 2004-03-30

Similar Documents

Publication Publication Date Title
KR101941302B1 (en) Method for adjusting the clamping force exerted by a parking brake
US5333707A (en) Controller for retarder
US5791745A (en) Brake pressure control system with the controlled pump for filling accumulator
KR100430171B1 (en) Hydraulic vehicle power brake device with at least one electrically controllable valve
US5326158A (en) Brake controlling apparatus for electric vehicle
JPH04331653A (en) Motor driven valve control hydraulic pump for feeding base pressure in brake pressure controller
JP4817479B2 (en) Method and apparatus for operating electric pump / motor of electrohydraulic pressure pump of automobile brake device
EP1808347A1 (en) Brake device and controller for the same
EP1529704B1 (en) Method and device for controlling regulation, drying and regeneration of a regulator dryer unit in a pneumatic-hydraulic braking system of a vehicle
JPH10194099A (en) Control method of pressure in at least one wheel brake and device thereof
KR970706160A (en) Hydraulic brake system and pressure control method (HYDRAULIC BRAKING SYSTEM AND PRESSURE-REGULATING METHOD)
JPH10236292A (en) Control method and device for pressure in at least single wheel brake
US6533369B2 (en) Brake system and method having secondary hydraulic braking in a de-energized operational mode
US6120107A (en) Compressor and air dryer control system
GB2312481A (en) Controlling the brake system of a vehicle
US6679565B2 (en) Gain scheduling for controlled force application
US6709073B2 (en) Control command modification to minimize saturation effects for controlled force application
JPH09290743A (en) Braking force control device
US6443535B1 (en) Deceleration and compensation for low vacuum levels in a brake-by-wire braking system
JPH09507661A (en) Electronic pressure relief system for traction slip control
WO2002090163A2 (en) Hydraulic vehicle retarder and method of controlling such retarder
US6585332B2 (en) Brake control device for a vehicle
JPH1148950A (en) Hydraulic pressure braking device
JP3826963B2 (en) Brake hydraulic pressure control device
US6070954A (en) Brake control system for an electrically operated vehicle

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SD SE SG SI SK SL TJ TM TN TR TT TZ UA UG US UZ VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase in:

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP