CA2161619A1 - Arrangement for preheating hydraulic circuits - Google Patents
Arrangement for preheating hydraulic circuitsInfo
- Publication number
- CA2161619A1 CA2161619A1 CA002161619A CA2161619A CA2161619A1 CA 2161619 A1 CA2161619 A1 CA 2161619A1 CA 002161619 A CA002161619 A CA 002161619A CA 2161619 A CA2161619 A CA 2161619A CA 2161619 A1 CA2161619 A1 CA 2161619A1
- Authority
- CA
- Canada
- Prior art keywords
- hydraulic
- oil
- piston rod
- preheating
- tank
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/04—Special measures taken in connection with the properties of the fluid
- F15B21/045—Compensating for variations in viscosity or temperature
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
- F15B15/08—Characterised by the construction of the motor unit
- F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
- F15B15/1423—Component parts; Constructional details
- F15B15/1485—Special measures for cooling or heating
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L53/00—Heating of pipes or pipe systems; Cooling of pipes or pipe systems
- F16L53/30—Heating of pipes or pipe systems
- F16L53/32—Heating of pipes or pipe systems using hot fluids
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/04—Special measures taken in connection with the properties of the fluid
- F15B21/042—Controlling the temperature of the fluid
- F15B21/0427—Heating
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
The preheating of hydraulic systems is prior art. It is generally done by operating the system without load until the prescribed minimum temperature is attained. However, in the known types of preheating circuits the operating elements (hydraulic cylinders) are not included. The invention relates to an arrangement in which the operating elements are included in the heating circuit.Appropriate circuits are provided for the various operating states of the hydraulic cylinder, i.e. "neutral", "retract piston rod" and "extend piston rod".
The provision of an additional passageway in the piston rod through which the hydraulic oil can pass into the hydraulic cylinder is an essential feature by means of which the oil can circulate without the application of pressure while the system is in the neutral operating state. By using the invention, it is possible to preheat hydraulic circuits in the neutral, non-operating state, thusavoiding damage to the operating elements, increasing the lifetime of the wear parts and guaranteeing reliable operation of the hydraulic system. The inventionis suitable in particular for use in conveyor systems operating in cold regions.
The provision of an additional passageway in the piston rod through which the hydraulic oil can pass into the hydraulic cylinder is an essential feature by means of which the oil can circulate without the application of pressure while the system is in the neutral operating state. By using the invention, it is possible to preheat hydraulic circuits in the neutral, non-operating state, thusavoiding damage to the operating elements, increasing the lifetime of the wear parts and guaranteeing reliable operation of the hydraulic system. The inventionis suitable in particular for use in conveyor systems operating in cold regions.
Description
-2-The invention relates to an invention for preheating hydraulic circuits, including the drive systems, in order to guarantee functional and op~,aLiolldl reliability. It is particularly suitable for the operation of hydraulic systems at low ambient temperatures, such as the operation of conveying equipment in cold 5 regions.
It is a known fact that at low ambient temperatures hydraulic systems can be got ready for operation by preheating the fluid reservoir or the hydraulic lines and by flushing hydraulic oil through the lines without the .~ tiol1 of pressure. For example, German Patent 268 044 describes a procedure and a 10 device for heating or cooling hydraulic lines; according to this procedure the system is preheated by heating up a section of the hydraulic lines by circulating hot air in a twin-chamber passageway. In this procedure, the hydraulic fluid is pumped around the system of hoses and tubing and is maintained at operating temperature. Intheilllllledià~vicinityoftheoperatingelement,e.g. ahydraulic 15 cylinder, a connecting line fitted with a short-circuit valve through which the hydraulic oil flows back is provided between the feed line and the return line.
In order to exclude the possibility of the operating element being influenced in an uncontrolled manner, the supply and return lines are each separated from the operating element by a shut-off valve. In this way, the 20 hydraulic fluid in the operating element is excluded from the heating circuit. If the ~perating element is then actuated, heated hydraulic fluid flows into the cold operating element and this leads to operational disturbances or increased wear. In extreme cases even a thermal shock, which is the most critical of all stresses, may occur. The functional disturbances caused in this manner do not 25 disappear again until these equipment elements have become thoroughly warmed up.
Operating elements which are operated relatively rarely and then only for short periods of time, are for the most part exposed to unfavourable operating conditions because at low ambient temperatures the operating elements arc 30 rarely if at all thoroughly heated.
, . , _ _ _ _ .. .. . _ . _
It is a known fact that at low ambient temperatures hydraulic systems can be got ready for operation by preheating the fluid reservoir or the hydraulic lines and by flushing hydraulic oil through the lines without the .~ tiol1 of pressure. For example, German Patent 268 044 describes a procedure and a 10 device for heating or cooling hydraulic lines; according to this procedure the system is preheated by heating up a section of the hydraulic lines by circulating hot air in a twin-chamber passageway. In this procedure, the hydraulic fluid is pumped around the system of hoses and tubing and is maintained at operating temperature. Intheilllllledià~vicinityoftheoperatingelement,e.g. ahydraulic 15 cylinder, a connecting line fitted with a short-circuit valve through which the hydraulic oil flows back is provided between the feed line and the return line.
In order to exclude the possibility of the operating element being influenced in an uncontrolled manner, the supply and return lines are each separated from the operating element by a shut-off valve. In this way, the 20 hydraulic fluid in the operating element is excluded from the heating circuit. If the ~perating element is then actuated, heated hydraulic fluid flows into the cold operating element and this leads to operational disturbances or increased wear. In extreme cases even a thermal shock, which is the most critical of all stresses, may occur. The functional disturbances caused in this manner do not 25 disappear again until these equipment elements have become thoroughly warmed up.
Operating elements which are operated relatively rarely and then only for short periods of time, are for the most part exposed to unfavourable operating conditions because at low ambient temperatures the operating elements arc 30 rarely if at all thoroughly heated.
, . , _ _ _ _ .. .. . _ . _
-3-The object of the invention is therefore to avoid these disadvantages.
According to the invention, an arrangement is provided for preheating hydraulic circuits in conveying machinery used in low-temperature environments. The purpose is to guarantee operational reliability by flushing out 5 the pipelines by circulating the oil in a non-pressurized state and by providing preheating of the oil reservoirs. In accordance with the invention, the hydraulic cylinder or hydraulic cylinders are included in the preheating circuit and for this purpose an additional transfer pas:,agc~ c~y is provided in the lifting piston rod.
This creates an additional Co11, ,eu~iul~ between the piston space and the system 10 of hydraulic lines. By means of the valves provided for the purpose, special circuits can be brought into operation to permit the non-pressurized circulationof the oil as well as to retract and extend the piston rod.
The specific hydraulic circuits for the three states provide - non-pressurized circulation - retracting piston rod and - extending piston rod.
The advantage of the invention is that when conveying machinery and other equipment is used in cold environments, the entire hydraulic system can be preheated to guarantee operational reliability and reduced wear, and as a 20 result normal operating conditions can be ,,,c,;,,L.. .,ed at all times.
An embodiment of the invention is illustrated in the drawing and described in more detail below. The drawing shows Fig. 1: AdidyldlllllldLiuviewofaheight-~ llct~hleboomforaconveying system, and5 Fig. 2: The circuit diagram for a simple hydraulic lifting device according to Fig. 1.
Fig. 1 depicts a boom 1 of the kind used as a discharge boom on an excavator, spreader or similar. This boom 1 can be pivoted horizontally by a
According to the invention, an arrangement is provided for preheating hydraulic circuits in conveying machinery used in low-temperature environments. The purpose is to guarantee operational reliability by flushing out 5 the pipelines by circulating the oil in a non-pressurized state and by providing preheating of the oil reservoirs. In accordance with the invention, the hydraulic cylinder or hydraulic cylinders are included in the preheating circuit and for this purpose an additional transfer pas:,agc~ c~y is provided in the lifting piston rod.
This creates an additional Co11, ,eu~iul~ between the piston space and the system 10 of hydraulic lines. By means of the valves provided for the purpose, special circuits can be brought into operation to permit the non-pressurized circulationof the oil as well as to retract and extend the piston rod.
The specific hydraulic circuits for the three states provide - non-pressurized circulation - retracting piston rod and - extending piston rod.
The advantage of the invention is that when conveying machinery and other equipment is used in cold environments, the entire hydraulic system can be preheated to guarantee operational reliability and reduced wear, and as a 20 result normal operating conditions can be ,,,c,;,,L.. .,ed at all times.
An embodiment of the invention is illustrated in the drawing and described in more detail below. The drawing shows Fig. 1: AdidyldlllllldLiuviewofaheight-~ llct~hleboomforaconveying system, and5 Fig. 2: The circuit diagram for a simple hydraulic lifting device according to Fig. 1.
Fig. 1 depicts a boom 1 of the kind used as a discharge boom on an excavator, spreader or similar. This boom 1 can be pivoted horizontally by a
-4-drive mechanism which is not further described here and it can be pivoted vertically by the hydraulic cylinder 2. In the process, a tensile load is applied to the hydraulic cylinder 2.
The designations used for the individual operating elements depicted in5 the circuit diagram for the simple hydraulic lifting device according to Fig. 2 are the desiy"alions p,t:s.,,iL,ed for such circuits and they reveal the operating principle of the circuit to any expert familiar with this field. Consequently, it is unnecessary to provide any further detailed descriptions of these operating elements and their method of operation.
One special feature that should be mentioned is that the pressure-limiting valve VD1 is used to protect the circuit against any ~""~ell"i~l~d excess pressure, the filter F with bypass VR3 is used to purify the returning fluid 3, and the flow control valve VDr1 is used to limit the lowering rate.
It is furthermore especially important that the piston rod 4 of the 15 hydraulic cylinder 2, which bears the customary designation MY1 in the circuit diagram shown in Fig . 2, possesses a passag~ ~r. dy (also referred to as "additional transfer" passag~u;) 6 running in the longitudinal direction.
In the unpressurized circulation mode, the pump P1 pumps oil 3 from the tank T through the ' ~-;Lio,1c,l control valve VW1; P-->A through 20 passageway 6 in the piston rod 4 of the hydraulic cylinder MY1 and into the piston space 5 of the cylinder. In the process, the check valve VR2 is forced open. The oil 3 emerging at connection point A on the hydraulic cylinder MY1 flows back into tank T via the directional control valve VW2; AB-- > T, which is in its open middle setting.
In this constellation, the pre-heated hydraulic oil 3 gives off heat to the working cylinder MY1. In addition, the opening pressure of the check valve VR2 generates an additional temperature increase which has a positive effect on the overall operation.
. ` 2161619
The designations used for the individual operating elements depicted in5 the circuit diagram for the simple hydraulic lifting device according to Fig. 2 are the desiy"alions p,t:s.,,iL,ed for such circuits and they reveal the operating principle of the circuit to any expert familiar with this field. Consequently, it is unnecessary to provide any further detailed descriptions of these operating elements and their method of operation.
One special feature that should be mentioned is that the pressure-limiting valve VD1 is used to protect the circuit against any ~""~ell"i~l~d excess pressure, the filter F with bypass VR3 is used to purify the returning fluid 3, and the flow control valve VDr1 is used to limit the lowering rate.
It is furthermore especially important that the piston rod 4 of the 15 hydraulic cylinder 2, which bears the customary designation MY1 in the circuit diagram shown in Fig . 2, possesses a passag~ ~r. dy (also referred to as "additional transfer" passag~u;) 6 running in the longitudinal direction.
In the unpressurized circulation mode, the pump P1 pumps oil 3 from the tank T through the ' ~-;Lio,1c,l control valve VW1; P-->A through 20 passageway 6 in the piston rod 4 of the hydraulic cylinder MY1 and into the piston space 5 of the cylinder. In the process, the check valve VR2 is forced open. The oil 3 emerging at connection point A on the hydraulic cylinder MY1 flows back into tank T via the directional control valve VW2; AB-- > T, which is in its open middle setting.
In this constellation, the pre-heated hydraulic oil 3 gives off heat to the working cylinder MY1. In addition, the opening pressure of the check valve VR2 generates an additional temperature increase which has a positive effect on the overall operation.
. ` 2161619
-5-The lower function is controlled by directional control valve VW2.
In this case, the solenoid a in ' ~iLiol-al control valve VW1 is energized and the passageway P-->A; B--~T is established. At the same time, the energized solenoid a in directional control valve VW1; P--> I blocks the 5 unpressurized circulation of the oil.
The oil 3 leaving directional control valve VW2 flows into the piston space 5, which is now sealed off by the check valve VR2. As the pressure builds up, it open up the holding valve VR1 via the pressure-limiting valve VD2.The oil 3 leaving on the differential side of the hydraulic cylinder MY1 is able10 to flow back into the tank T via the passag~wdy connection in the directional control valve VW2; B-->T. The hydraulic cylinder MY1 is extended.
When the solenoids a of d;,el,Lional control valves VW1 and VW 2 are switched off, the process comes to an end. The control pressure drops up via the flow control valve VDr2 and the holding valve VR1 locks the hydraulic 15 cylinder MY1.
The raise function is controlled via ' t:-,Lio,1cl1 control valve VW2.
In this case, the solenoid b of directional control valve VW1 is energized and the passageway P~>B, A-->T is established. At the same time, the energized solenoid a of the directional control valve VW1; P-- I, T-- I blocks the 20 unpressurized circulation of the oil.
The oil 3 emerges from the passaU~.,y B of directional control valve VW2 and flows through the return valve VR1 into piston rod space 7. The oil 3 emerging on the piston side of the hydraulic cylinder MY1 is able to flow back into the tank T via the passageway A-->T in directional control valve 25 VW2. The hydraulic cylinder MY1 is retracted.
In this case, the solenoid a in ' ~iLiol-al control valve VW1 is energized and the passageway P-->A; B--~T is established. At the same time, the energized solenoid a in directional control valve VW1; P--> I blocks the 5 unpressurized circulation of the oil.
The oil 3 leaving directional control valve VW2 flows into the piston space 5, which is now sealed off by the check valve VR2. As the pressure builds up, it open up the holding valve VR1 via the pressure-limiting valve VD2.The oil 3 leaving on the differential side of the hydraulic cylinder MY1 is able10 to flow back into the tank T via the passag~wdy connection in the directional control valve VW2; B-->T. The hydraulic cylinder MY1 is extended.
When the solenoids a of d;,el,Lional control valves VW1 and VW 2 are switched off, the process comes to an end. The control pressure drops up via the flow control valve VDr2 and the holding valve VR1 locks the hydraulic 15 cylinder MY1.
The raise function is controlled via ' t:-,Lio,1cl1 control valve VW2.
In this case, the solenoid b of directional control valve VW1 is energized and the passageway P~>B, A-->T is established. At the same time, the energized solenoid a of the directional control valve VW1; P-- I, T-- I blocks the 20 unpressurized circulation of the oil.
The oil 3 emerges from the passaU~.,y B of directional control valve VW2 and flows through the return valve VR1 into piston rod space 7. The oil 3 emerging on the piston side of the hydraulic cylinder MY1 is able to flow back into the tank T via the passageway A-->T in directional control valve 25 VW2. The hydraulic cylinder MY1 is retracted.
Claims (4)
1. An arrangement for preheating hydraulic circuits in conveying machinery used in low-temperature environments, the purpose being to guarantee operational reliability by flushing out the pipelines by circulating the oil in a non-pressurized state and by providing preheating of the oil reservoirs, characterized in that the hydraulic cylinder or hydraulic cylinders (2) are included in the preheating circuit and for this purpose an additional transfer passageway (6) is provided in the lifting piston rod (4), thus creating an additional connection between the piston space (5) and the system of hydraulic lines, and furthermore by means of the valves provided for the purpose, special circuits can be brought into operation to permit the non-pressurized circulationof the oil as well as to retract and extend the piston rod (4).
2. An arrangement for preheating hydraulic circuits according to Claim 1, characterized in that, when in the non-pressurized oil circulation mode, the valves provide for circulation of the oil from the tank (T), via the passageway (6) in the piston rod (4), into the piston space (5) of the hydrauliccylinder (MY1) and back into tank (T).
3. An arrangement for preheating hydraulic circuits according to Claim 1, characterized in that in order to extend the piston rod (4), oil (3) ispumped from the tank (T) into the piston space (5) of the hydraulic cylinder (MY1) and while the pressure is being applied, excess oil (3) can flow back from the piston rod space (7) into the tank (T) and the extending of the piston rod is terminated by closing all the valves.
4. An arrangement for preheating hydraulic circuits according to Claim 1, characterized in that the retraction of the piston rod (4) is accomplished by directing the hydraulic oil (3) from the tank (T) into the piston rod space (7) while at the same time forcing the hydraulic oil (3) from the piston space (5) into the tank (T) and the retraction process is terminated by closing all the valves.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4439454A DE4439454C2 (en) | 1994-11-04 | 1994-11-04 | Circuit arrangement for preheating hydraulic circuits |
| DEP4439454.3 | 1994-11-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2161619A1 true CA2161619A1 (en) | 1996-03-12 |
Family
ID=6532502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002161619A Abandoned CA2161619A1 (en) | 1994-11-04 | 1995-10-27 | Arrangement for preheating hydraulic circuits |
Country Status (4)
| Country | Link |
|---|---|
| CN (1) | CN1130726A (en) |
| CA (1) | CA2161619A1 (en) |
| DE (1) | DE4439454C2 (en) |
| RU (1) | RU2140022C1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9403434B2 (en) | 2014-01-20 | 2016-08-02 | Posi-Plus Technologies Inc. | Hydraulic system for extreme climates |
| CN113309747A (en) * | 2021-06-24 | 2021-08-27 | 陕西法士特齿轮有限责任公司 | Hydraulic valve block temperature control simulation system and test method for hydraulic automatic transmission |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19627974C2 (en) * | 1996-07-11 | 2003-02-06 | Getrag Getriebe Zahnrad | Hydraulic actuator and method for bleeding a hydraulic actuator |
| JP2003097516A (en) | 2001-09-25 | 2003-04-03 | Hitachi Ltd | Hydraulic device |
| DE10230860A1 (en) * | 2002-07-09 | 2004-01-22 | Zf Friedrichshafen Ag | Hydraulic fluid system for a hydraulic control unit comprises a hydraulic fluid filter is arranged between a pressure control valve and a hydraulic fluid reservoir |
| DE10313487A1 (en) | 2003-03-26 | 2004-10-14 | Zf Friedrichshafen Ag | Hydraulic system for driving load, has pressure fluid source that pumps out fluid from fluid reservoir to actuate loads, in which each load has pressure fluid supply lines that connect to pressure fluid source based on actuation of load |
| CN101743362A (en) * | 2007-06-29 | 2010-06-16 | 维米尔制造公司 | Hydraulic system with thermal shock protection |
| EP2282029B2 (en) | 2009-06-29 | 2022-04-20 | Joseph Vögele AG | Self-propelled machine |
| CN102003430B (en) * | 2010-11-23 | 2013-01-02 | 山东钢铁股份有限公司 | Hydraulic cylinder |
| WO2012086695A1 (en) * | 2010-12-21 | 2012-06-28 | 株式会社小松製作所 | Pipe layer and warm-up method for pipe layer |
| CN102418725B (en) * | 2011-10-24 | 2013-03-20 | 中联重科股份有限公司 | Pumping equipment and distribution hydraulic system |
| CN102788050A (en) * | 2012-07-27 | 2012-11-21 | 柳州柳工挖掘机有限公司 | Oil changing and buffering device and pilot hydraulic control system with same |
| DE102013221082A1 (en) * | 2013-10-17 | 2015-04-23 | Robert Bosch Gmbh | hydraulic cylinders |
| RU2555095C1 (en) * | 2014-02-25 | 2015-07-10 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Тюменский государственный нефтегазовый университет" (ТюмГНГУ) | Hydrocylinder with movable piston part |
| AT514919B1 (en) * | 2014-06-25 | 2015-05-15 | Avl List Gmbh | METHOD FOR OPERATING AN AUTOMATIC TRANSMISSION OR A DOUBLE COUPLING GEARBOX |
| FR3044054B1 (en) * | 2015-11-20 | 2018-08-10 | Db Industries | AUTOMATIC RINSING DEVICE FOR HYDRAULIC CYLINDERS WITH DOUBLE EFFECT |
| NL2017106B1 (en) * | 2016-07-05 | 2017-06-13 | Fugro N V | Unmanned underwater vehicle and method for controlling hydraulic system |
| CN110513361A (en) * | 2019-09-02 | 2019-11-29 | 柳州柳工挖掘机有限公司 | Construction machinery hydraulic system and hydraulic oil method for controlling temperature rise |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CS237612B1 (en) * | 1983-01-31 | 1985-09-17 | Ladislav Rach | Wiring diagram for temperature regulation of working liquid |
| DD268044A1 (en) * | 1987-12-11 | 1989-05-17 | Verlade Und Transportanlagen P | METHOD AND DEVICE FOR HEATING OR COOLING HYDRAULIC PIPING |
-
1994
- 1994-11-04 DE DE4439454A patent/DE4439454C2/en not_active Expired - Fee Related
-
1995
- 1995-10-27 CA CA002161619A patent/CA2161619A1/en not_active Abandoned
- 1995-11-01 CN CN95118149A patent/CN1130726A/en active Pending
- 1995-11-02 RU RU95118728A patent/RU2140022C1/en active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9403434B2 (en) | 2014-01-20 | 2016-08-02 | Posi-Plus Technologies Inc. | Hydraulic system for extreme climates |
| CN113309747A (en) * | 2021-06-24 | 2021-08-27 | 陕西法士特齿轮有限责任公司 | Hydraulic valve block temperature control simulation system and test method for hydraulic automatic transmission |
Also Published As
| Publication number | Publication date |
|---|---|
| DE4439454C2 (en) | 1997-09-04 |
| CN1130726A (en) | 1996-09-11 |
| DE4439454A1 (en) | 1996-05-09 |
| RU2140022C1 (en) | 1999-10-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20021028 |