EP0724542B1 - Electrohydraulic lifting device for motor vehicles - Google Patents

Electrohydraulic lifting device for motor vehicles Download PDF

Info

Publication number
EP0724542B1
EP0724542B1 EP95900255A EP95900255A EP0724542B1 EP 0724542 B1 EP0724542 B1 EP 0724542B1 EP 95900255 A EP95900255 A EP 95900255A EP 95900255 A EP95900255 A EP 95900255A EP 0724542 B1 EP0724542 B1 EP 0724542B1
Authority
EP
European Patent Office
Prior art keywords
conduit
main cylinder
fluid
cylinder
support platforms
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.)
Expired - Lifetime
Application number
EP95900255A
Other languages
German (de)
French (fr)
Other versions
EP0724542A1 (en
Inventor
Fausto Manganelli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ravaglioli SpA
Original Assignee
Ravaglioli SpA
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 Ravaglioli SpA filed Critical Ravaglioli SpA
Publication of EP0724542A1 publication Critical patent/EP0724542A1/en
Application granted granted Critical
Publication of EP0724542B1 publication Critical patent/EP0724542B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F7/00—Lifting frames, e.g. for lifting vehicles; Platform lifts
    • B66F7/06—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement
    • B66F7/08—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement hydraulically or pneumatically operated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F7/00—Lifting frames, e.g. for lifting vehicles; Platform lifts
    • B66F7/06—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported by levers for vertical movement
    • B66F7/065—Scissor linkages, i.e. X-configuration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F7/00—Lifting frames, e.g. for lifting vehicles; Platform lifts
    • B66F7/10—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported directly by jacks
    • B66F7/16—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported directly by jacks by one or more hydraulic or pneumatic jacks
    • B66F7/20—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms supported directly by jacks by one or more hydraulic or pneumatic jacks by several jacks with means for maintaining the platforms horizontal during movement
    • 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/22—Synchronisation of the movement of two or more servomotors

Definitions

  • the present invention relates to the technical field concerned with devices used to lift motor vehicles.
  • scissor lifts that are adapted to be fixed to the floor or to be set in a properly prepared seat.
  • the above mentioned devices basically include a pair of support platforms 1 that are horizontal and parallel to one another, these support platforms being long enough to hold the vehicle to be lifted.
  • the support platforms 1 are mounted on pairs of tie rods 2 which are hinged to one another at their midpoint, like a scissor, while respective cylinders 3 are connected to them.
  • sloped tracks 4 aimed at permitting a vehicle to run over the support platforms 1.
  • the support platforms are also equipped with stops 5,6 at their ends.
  • Such a device being known from DE-A-3499292.
  • the support platforms are not bound to each other, and they are mounted independently from each other, so that the space defined between them is left free and accessible.
  • the support platforms are moved by means of a hydraulic control unit that has the task of controlling the supply and discharge of the hydraulic pressure media to and from the respective cylinders, as it is shown in the diagram in Figure 3.
  • P1 and P2 respectively indicate the main cylinder and the secondary cylinder of the support platforms, while the support platforms are indicated by 1a, the former, and 1b the latter.
  • the main cylinder P1 is supplied, via the conduit 7, with fluid coming from the pump 8 that is operated by a motor 9.
  • a branch 10 starts from the conduit 7, downstream of the pump 8, and serves as a return way for the hydraulic media to the reservoir 11.
  • the branch 10 includes the solenoid valve 12, activated during the lowering stage, and the flow rate adjustment valve 13.
  • the main cylinder P1 in its turn, feeds the secondary cylinder P2 via the conduit 14.
  • Both the main cylinder and the secondary cylinder are equipped with respective cutoff valves 15.
  • Feeding the main cylinder P1 causes a certain volume of hydraulic media to flow from this cylinder to the secondary cylinder P2 that is in this way also fed.
  • the secondary cylinder P2 has a cross section reduced with respect to the main cylinder P1, that is, the cross section of the inner chamber of the secondary cylinder P2 has the same area as the working cross section area of the inner chamber of the main cylinder P1, i.e. the area calculated taking into account the presence of the stem therein.
  • the volume of fluid that is first displaced from the main cylinder P1 to the secondary cylinder P2 returns than back to the main cylinder P1 in the discharge stage, that is when the support platforms are lowered.
  • the support platforms remain at different height, that is the first support platform 1a is at an higher level than the second support platform 1b.
  • the second cylinder P2 is delayed with respect to the first cylinder P1, and this is due to the compressibility of the hydraulic fluid. Because of the compressibility of the hydraulic fluid, an initial motion of the plunger of the cylinder P1 does not determine a corresponding fluid displacement but only a fluid compression, and therefore the cylinder P2 is not operated.
  • This delay effect is increased at the starting because this condition is the one in which the fluid is at the maximum pressure, considering a certain constant load, and because the cylinders are in an almost horizontal position, and therefore the ratio between the vertical motion of the support platforms and the motion of the plungers is the highest.
  • the two cylinders P1 and P2 are fed independent from one another (for example, by means of a flow distributor valve) and synchronism of the two support platforms 1a,1b is obtained by means of a mechanical linkage set between the tie rods 2 (see Fig. 1a).
  • German patent DE 3439292 discloses a synchronisation device comprising two valves, the first of whose is located between the recycling conduit, connecting the main cylinder to the secondary cylinder, and a discharge reservoir; the second valve is located between the same conduit and the main hydraulic conduit.
  • the first valve is normally closed, and it is opened by a first support platform, moved by the secondary cylinder, when it reaches its upper end position.
  • the second valve is normally closed, and it is opened by a second support platform, moved by the main cylinder, when it reaches its upper end position.
  • the platforms are nonaligned, in order to get them into alignment, they must be taken to their higher position, by connecting the recycling conduit either to a discharge, if the first platform is higher than the second one, or to the main circuit, if said first platform is lower.
  • That mode of operation leads to some undesirable situations in operating the lifting device.
  • the object of the present invention is to contrive an electrohydraulic lifting device in which the motion of the two support platforms is kept synchronous and in which the support platforms are perfectly in alignment with each other, when they are at the floor level at the end of every working cycle. This is obtained by providing for a compensation to the compressing action of the hydraulic media at the starting.
  • an electrohydraulic lifting device for motor vehicles includes a pair of support platforms, respectively a first support platform and a second support platform, which are horizontal and parallel to each other, and mounted on respective tie rods respectively actuated by a main cylinder and by a secondary cylinder.
  • the secondary cylinder is fed by the main cylinder, under the control of a hydraulic control unit.
  • the hydraulic control unit is equipped with a synchronisation device including a synchronisation valve (18) aimed at connecting a hydraulic media conduit, delivering hydraulic fluid to the said main cylinder, with a recycling conduit leading a suitable volume of hydraulic fluid from the same main cylinder to the secondary cylinder, so as to compensate the inadequacy of the delivery of fluid to the secondary cylinder, or alternatively aimed at deviating an exceeding part of the recycled fluid to a discharge, respectively at the starting and when the support platforms are getting into alignment at the floor level.
  • a synchronisation device including a synchronisation valve (18) aimed at connecting a hydraulic media conduit, delivering hydraulic fluid to the said main cylinder, with a recycling conduit leading a suitable volume of hydraulic fluid from the same main cylinder to the secondary cylinder, so as to compensate the inadequacy of the delivery of fluid to the secondary cylinder, or alternatively aimed at deviating an exceeding part of the recycled fluid to
  • the electrohydraulic control unit 16 of the subject lifting device includes a synchronisation device 17 that is aimed at keeping the synchronism of the motion of the two support platforms 1a and 1b.
  • This synchronisation device 17 is equipped with a mechanically operated valve 18 that is mounted on an auxiliary conduit 19 through which the hydraulic media is delivered to the secondary cylinder P2.
  • the auxiliary conduit 19 starts from the conduit 20 used to feed the main cylinder P1.
  • the normally closed two-way synchronisation valve 18 is controlled by the support platform 1b, by means of a push rod 21.
  • the part of the conduit 19 downstream of the synchronisation valve 18, is connected to the recycling conduit 22 that leads the hydraulic flow from the main cylinder P1 to the secondary cylinder P2.
  • the conduit 22 there is set a pressure switch 23 and a normally closed cock 24 connected to the supply conduit 20.
  • the raising motion of the support platform 1b causes the synchronisation valve 18 to close, so that afterwards, during the raising motion of the support platforms, the conduits 20 and 22 are no longer connected to each other. Then, the secondary cylinder P2 is supplied only with the fluid displaced from the main cylinder P1 through the recycling conduit 22 (See Figure 5).
  • the fluid used to actuate the main cylinder P1 is instead sent to the reservoir 11 through the conduit 10 after that the solenoid valve 12 has been properly opened.
  • the support platform 1b provokes again opening of the synchronisation valve 18, so that the fluid from the secondary cylinder P2 also flows through the auxiliary conduit 19 (see Figure 7).
  • the support platform 1b keeps the synchronisation valve 18 open through a rising stroke of about 10 mms.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Forklifts And Lifting Vehicles (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

The electrohydraulic lifting device for motor vehicles includes a pair of support platforms (1), respectively a first support platform and a second support platform, which are horizontal and parallel to each other, and mounted on respective tie rods (2) respectively actuated by a main cylinder (P1) and by a secondary cylinder (P2) fed by the same main cylinder (P1), under the control of a hydraulic control unit (16). The hydraulic control unit (16) is equipped with a synchronisation device (17) including a synchronization valve (18) aimed at connecting a hydraulic media conduit (20), delivering hydraulic fluid to the said main cylinder (P1), with a recycling conduit (22) leading a suitable volume of hydraulic fluid from the same main cylinder (P1) to the secondary cylinder (P2), so that to compensate the inadequacy of the delivery of fluid to the secondary cylinder (P2), or alternatively aimed at deviating an exceeding part of the recycled fluid to a discharge, respectively at the starting and when the support platforms (1) are getting into alignment at the floor level.

Description

TECHNICAL FIELD
The present invention relates to the technical field concerned with devices used to lift motor vehicles.
BACKGROUND ART
Presently, it is known to use electrohydraulic devices which allow to lift motor vehicles up to a height that is suitable to make their lower part accessible.
Particularly there are known devices, so called scissor lifts, that are adapted to be fixed to the floor or to be set in a properly prepared seat.
As it is shown, for example, in Fig. 1a,1b and 2, the above mentioned devices basically include a pair of support platforms 1 that are horizontal and parallel to one another, these support platforms being long enough to hold the vehicle to be lifted.
The support platforms 1 are mounted on pairs of tie rods 2 which are hinged to one another at their midpoint, like a scissor, while respective cylinders 3 are connected to them.
If the lifting device is fixed to the floor, there will be provided sloped tracks 4 aimed at permitting a vehicle to run over the support platforms 1.
To give safety, the support platforms are also equipped with stops 5,6 at their ends. Such a device being known from DE-A-3499292.
In the above mentioned devices, the problem arises that concerns the synchronisation of the support platforms movements, in any operation conditions.
In fact, the support platforms are not bound to each other, and they are mounted independently from each other, so that the space defined between them is left free and accessible.
For this purpose the support platforms are moved by means of a hydraulic control unit that has the task of controlling the supply and discharge of the hydraulic pressure media to and from the respective cylinders, as it is shown in the diagram in Figure 3.
For sake of clarity, in this diagram P1 and P2 respectively indicate the main cylinder and the secondary cylinder of the support platforms, while the support platforms are indicated by 1a, the former, and 1b the latter.
The main cylinder P1 is supplied, via the conduit 7, with fluid coming from the pump 8 that is operated by a motor 9.
A branch 10 starts from the conduit 7, downstream of the pump 8, and serves as a return way for the hydraulic media to the reservoir 11. The branch 10 includes the solenoid valve 12, activated during the lowering stage, and the flow rate adjustment valve 13.
The main cylinder P1, in its turn, feeds the secondary cylinder P2 via the conduit 14. Both the main cylinder and the secondary cylinder are equipped with respective cutoff valves 15.
Feeding the main cylinder P1 causes a certain volume of hydraulic media to flow from this cylinder to the secondary cylinder P2 that is in this way also fed.
It must be noted that the secondary cylinder P2 has a cross section reduced with respect to the main cylinder P1, that is, the cross section of the inner chamber of the secondary cylinder P2 has the same area as the working cross section area of the inner chamber of the main cylinder P1, i.e. the area calculated taking into account the presence of the stem therein.
In this way the volume of fluid that is displaced to the secondary cylinder P2 theoretically is equal to the volume of fluid delivered to the main cylinder P1, so that like displacements occur for both the support platforms.
The volume of fluid that is first displaced from the main cylinder P1 to the secondary cylinder P2 returns than back to the main cylinder P1 in the discharge stage, that is when the support platforms are lowered.
In this stage the fluid that is contained in the main cylinder is instead discharged into the reservoir 11, because of the opening of a solenoid valve 12.
Generally, a synchronical motion is not always assured for the two support platforms, particularly because of small leakages of the fluid through the seals of the plungers of the cylinders. These leakages may cause a variation of the volume of fluid that is displaced, and consequently the synchronical motion of the platforms can be lost.
If the volume of the fluid supplied to the cylinder P2 is increased, then e.g. in the discharge stage the plunger of this cylinder will not return to the correct position, and this would provoke a nonalignment of the support platform when they are at the floor level.
If the volume of the fluid supplied to the cylinder P2 decreases, then the support platforms remain at different height, that is the first support platform 1a is at an higher level than the second support platform 1b.
Furthermore, usually at the starting the second cylinder P2 is delayed with respect to the first cylinder P1, and this is due to the compressibility of the hydraulic fluid. Because of the compressibility of the hydraulic fluid, an initial motion of the plunger of the cylinder P1 does not determine a corresponding fluid displacement but only a fluid compression, and therefore the cylinder P2 is not operated.
This delay effect is increased at the starting because this condition is the one in which the fluid is at the maximum pressure, considering a certain constant load, and because the cylinders are in an almost horizontal position, and therefore the ratio between the vertical motion of the support platforms and the motion of the plungers is the highest.
According to another known solution, the two cylinders P1 and P2 are fed independent from one another (for example, by means of a flow distributor valve) and synchronism of the two support platforms 1a,1b is obtained by means of a mechanical linkage set between the tie rods 2 (see Fig. 1a).
This expedient does not result in an optimal effect because of the considerable mechanical stress (mainly torsional stress) that affect the parts of this mechanical linkage.
A further solution for synchronising the support platforms is known from German patent DE 3439292. Said document discloses a synchronisation device comprising two valves, the first of whose is located between the recycling conduit, connecting the main cylinder to the secondary cylinder, and a discharge reservoir; the second valve is located between the same conduit and the main hydraulic conduit.
The first valve is normally closed, and it is opened by a first support platform, moved by the secondary cylinder, when it reaches its upper end position.
In a similar way, the second valve is normally closed, and it is opened by a second support platform, moved by the main cylinder, when it reaches its upper end position.
Thus, if the platforms are nonaligned, in order to get them into alignment, they must be taken to their higher position, by connecting the recycling conduit either to a discharge, if the first platform is higher than the second one, or to the main circuit, if said first platform is lower.
That mode of operation leads to some undesirable situations in operating the lifting device.
In fact, the load supported by the platforms must be taken to a high position, while being highly unbalanced. This can be dangerous for both the load and the operators staying close to the lifting device.
DISCLOSURE OF THE INVENTION
The object of the present invention is to contrive an electrohydraulic lifting device in which the motion of the two support platforms is kept synchronous and in which the support platforms are perfectly in alignment with each other, when they are at the floor level at the end of every working cycle. This is obtained by providing for a compensation to the compressing action of the hydraulic media at the starting.
The above mentioned object is achieved by an electrohydraulic lifting device for motor vehicles includes a pair of support platforms, respectively a first support platform and a second support platform, which are horizontal and parallel to each other, and mounted on respective tie rods respectively actuated by a main cylinder and by a secondary cylinder.
The secondary cylinder is fed by the main cylinder, under the control of a hydraulic control unit. The hydraulic control unit is equipped with a synchronisation device including a synchronisation valve (18) aimed at connecting a hydraulic media conduit, delivering hydraulic fluid to the said main cylinder, with a recycling conduit leading a suitable volume of hydraulic fluid from the same main cylinder to the secondary cylinder, so as to compensate the inadequacy of the delivery of fluid to the secondary cylinder, or alternatively aimed at deviating an exceeding part of the recycled fluid to a discharge, respectively at the starting and when the support platforms are getting into alignment at the floor level.
BRIEF DESCRIPTION OF THE DRAWINGS
The characteristic features of the invention are set out in the following description, with particular reference to the accompanying drawings, in which:
  • Figures 1a and 1b show schematic side views of a lifting device, in a raised position and in a lowered position respectively;
  • Figure 2 shows a plan view of the lifting device;
  • Figure 3 shows a schematic diagram of the operation facility set up for a conventional lifting device;
  • Figure 4 shows a schematic diagram of the electrohydraulic operation facility set up for the lifting device made in accordance with the present invention, as it looks at the starting;
  • Figures 5, 6 and 7 show the same diagram of the electrohydraulic operation facility at an intermediate raising stage, at an intermediate lowering stage and when they are getting in mutual alignment on the floor, respectively.
BEST MODE OF CARRYING OUT THE INVENTION
Having reference to the above mentioned figures 4,5,6 and 7, the electrohydraulic control unit 16 of the subject lifting device, includes a synchronisation device 17 that is aimed at keeping the synchronism of the motion of the two support platforms 1a and 1b.
This synchronisation device 17 is equipped with a mechanically operated valve 18 that is mounted on an auxiliary conduit 19 through which the hydraulic media is delivered to the secondary cylinder P2. The auxiliary conduit 19 starts from the conduit 20 used to feed the main cylinder P1.
The normally closed two-way synchronisation valve 18 is controlled by the support platform 1b, by means of a push rod 21.
The part of the conduit 19 downstream of the synchronisation valve 18, is connected to the recycling conduit 22 that leads the hydraulic flow from the main cylinder P1 to the secondary cylinder P2. Along the conduit 22 there is set a pressure switch 23 and a normally closed cock 24 connected to the supply conduit 20.
Operation of the device will be described in the following, beginning from the starting stage as it is shown in Figure 4.
In this stage the synchronisation valve 18 is open because of the thrust made by the support platform 1b on the push rod 21.
Therefore the hydraulic media delivered by the pump 8 to the main cylinder P1 via the conduit 20, is partially deviated to the secondary cylinder P2 via the auxiliary conduit 19.
In this way the delay in displacing the fluid from the main cylinder P1 to the secondary cylinder P2 through the recycling conduit 22, due to the compression of the fluid, is compensated by the volume of fluid directly fed to the cylinder P2, and the synchronous motion of the support platform 1a and 1b is therefore assured.
The raising motion of the support platform 1b causes the synchronisation valve 18 to close, so that afterwards, during the raising motion of the support platforms, the conduits 20 and 22 are no longer connected to each other. Then, the secondary cylinder P2 is supplied only with the fluid displaced from the main cylinder P1 through the recycling conduit 22 (See Figure 5).
In a similar way, when the support platforms are lowering, since the synchronisation valve 18 is closed, the fluid present into the secondary cylinder P2 flows back to the main cylinder P1 only through the recycling conduit 22 (see Figure 6).
The fluid used to actuate the main cylinder P1, is instead sent to the reservoir 11 through the conduit 10 after that the solenoid valve 12 has been properly opened.
When the support platforms reach the floor level, the support platform 1b provokes again opening of the synchronisation valve 18, so that the fluid from the secondary cylinder P2 also flows through the auxiliary conduit 19 (see Figure 7).
In this way, hydraulic fluid in excess, due to possible leakages, is directly discharged into the reservoir 11. On the contrary, a possible inadequacy of the fluid present in the main cylinder P1 is compensated by deviating a part of the fluid being discharged from the same main cylinder P1, to the recycling conduit 22.
The support platform 1b keeps the synchronisation valve 18 open through a rising stroke of about 10 mms.
In the lifting device just described, the problem of keeping the support platforms in alignment when at floor level at the end of every working cycle, is therefore solved. Also the problem of maintaining the synchronism of the two support platforms at the starting stage, due to the fluid compressibility, is solved.
It is understood that what has been described above is only illustrative, therefore possible constructive variants are within the protection of the present invention as described hereinabove and claimed in the following.

Claims (5)

  1. Electrohydraulic lifting device for motor vehicles, including a pair of support platforms (1a,1b), respectively a first support platform and a second support platform, which are horizontal and parallel to each other, these support platforms (1a,1b) being mounted on respective tie rods (2) and respectively set in motion by a main cylinder (P1) and a secondary cylinder (P2) that is fed by the main cylinder (P1), under the control of an electrohydraulic control unit (16), which is equipped with a synchronisation device (17) placed along an auxiliary conduit (19), connecting a hydraulic media conduit (20) delivering hydraulic fluid to the said main cylinder (P1), with a recycling conduit (22) leading a suitable volume of hydraulic fluid from the same main cylinder (P1) to the said secondary cylinder (P2), the said lifting device being characterised in that said synchronisation device (17) includes a single synchronisation valve (18), aimed at opening the said connection between the hydraulic media conduit (20) and the recycling conduit (22) at the starting of the support platforms (1a,1b) from the floor level, or alternatively aimed at deviating an exceeding part of the recycled fluid to a discharge, when said support platforms (1a,1b) are reaching the floor level, to get them into alignment.
  2. Device as claimed in claim 1, characterised in that the said synchronisation valve (18) is mechanically operated, either to get open or closed, as a consequence of the lowering or raising of the said support platform (1b) respectively.
  3. Device as claimed in claim 1, characterised in that, when said support platforms (1a,1b) are starting from the floor level, some more hydraulic fluid is allowed to be pumped into said recycling conduit (22).
  4. Device as claimed in claim 1, characterised in that during normal operation, when the said support platforms (1a,1b) are raising or lowering, the said synchronisation valve (18) is normally closed, so that the said delivery conduit and the said recycling conduit (22) are not connected with each other, and the said secondary cylinder (P2) is fed only with the hydraulic fluid coming from the said main cylinder (P1) through the said recycling conduit (22).
  5. Device as claimed in claim 1, characterised in that when the support platforms are getting into alignment at the floor level, said synchronisation valve (18) is opened to deviate part of the fluid being discharged from the same main cylinder (P1) to the recycling conduit (22) for compensation of inadequacy of the recycling fluid present in said main cylinder (P1).
EP95900255A 1993-10-22 1994-10-19 Electrohydraulic lifting device for motor vehicles Expired - Lifetime EP0724542B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IT93BO000421A IT1264250B1 (en) 1993-10-22 1993-10-22 "ELECTRO-HYDRAULIC LIFT DEVICE FOR VEHICLES"
ITBO930421 1993-10-22
PCT/IT1994/000176 WO1995011190A1 (en) 1993-10-22 1994-10-19 Electrohydraulic lifting device for motor vehicles

Publications (2)

Publication Number Publication Date
EP0724542A1 EP0724542A1 (en) 1996-08-07
EP0724542B1 true EP0724542B1 (en) 1998-05-13

Family

ID=11339278

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95900255A Expired - Lifetime EP0724542B1 (en) 1993-10-22 1994-10-19 Electrohydraulic lifting device for motor vehicles

Country Status (7)

Country Link
EP (1) EP0724542B1 (en)
AT (1) ATE166038T1 (en)
AU (1) AU8114694A (en)
DE (2) DE724542T1 (en)
ES (1) ES2116062T3 (en)
IT (1) IT1264250B1 (en)
WO (1) WO1995011190A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110219841A (en) * 2019-06-14 2019-09-10 中国矿业大学(北京) The hydraulic system of instantaneous off-load

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITVI980165A1 (en) * 1998-09-07 2000-03-07 Francesco Fiorese HYDRAULIC CIRCUIT FOR THE OPERATION OF SERVICE BRIDGES FOR THE LIFTING OF VEHICLES
IT1302678B1 (en) * 1998-10-15 2000-09-29 Texo Srl VOLUMETRIC DRIVE SYSTEM FOR VEHICLE LIFTING LINKS.
SE517223C2 (en) * 2000-09-20 2002-05-14 Morphic Technologies Ab Hydraulic device for synchronizing at least two cooperating hydraulic pistons
CN1331725C (en) * 2003-12-31 2007-08-15 深圳市汇银实业开发有限公司 Swing type lifter for assembling four link torsional force axial type synchro
CN103407933B (en) * 2012-09-03 2017-05-31 希实本株式会社 Vehicle lifting with synchronizing function
CN102992224A (en) * 2012-12-01 2013-03-27 江苏华宏科技股份有限公司 Multi-hydraulic-cylinder electro-hydraulic synchronous lifting system

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3476016A (en) * 1967-10-20 1969-11-04 Cascade Corp Apparatus for producing coordinated,simultaneous actuation of multiple rams
DE3439292A1 (en) * 1984-10-26 1986-05-07 Otto Nußbaum GmbH & Co KG, 7640 Kehl Hydraulically operated lifting device, especially lifting platform for motor vehicles
US5072649A (en) * 1991-01-07 1991-12-17 Laghi Aldo A Double actuator with bypass lines for synchronized movement
NL9200686A (en) * 1992-04-13 1993-11-01 Stertil Bv APPARATUS WITH SIMULTANEOUS HYDRAULIC JACKS.

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110219841A (en) * 2019-06-14 2019-09-10 中国矿业大学(北京) The hydraulic system of instantaneous off-load

Also Published As

Publication number Publication date
EP0724542A1 (en) 1996-08-07
ATE166038T1 (en) 1998-05-15
DE724542T1 (en) 1997-04-03
ITBO930421A0 (en) 1993-10-22
DE69410283D1 (en) 1998-06-18
ES2116062T3 (en) 1998-07-01
WO1995011190A1 (en) 1995-04-27
DE69410283T2 (en) 1998-10-01
ITBO930421A1 (en) 1994-01-22
IT1264250B1 (en) 1996-09-23
AU8114694A (en) 1995-05-08

Similar Documents

Publication Publication Date Title
CA1308626C (en) Hydraulic actuating unit, in particular for raising a load, such as a hospital bed
EP0724542B1 (en) Electrohydraulic lifting device for motor vehicles
AU740391B2 (en) Hydraulically trippable check valve for underground mine support hydraulics
US5060762A (en) Pressure intensifier for repositioning telescopic plungers in synchronized telescopic cylinders
EP0724541B1 (en) Electrohydraulic lifting device
JPH08170569A (en) Common rail type fuel injection device for internal combustion engine
US4371294A (en) Slurry conveyor system
US4376612A (en) Earthworking machine of the loader type
US10202985B2 (en) System preventing pressured oil leakage to cylinder line in control valve systems with flow divider
US5323698A (en) Press for compressing drums of contaminated waste
JPH05312202A (en) Position-controlled proportional directional valve
US4460152A (en) Hand pump with automatic lock-out
US3048016A (en) Hydraulic drive for electric switchgear
AU6523299A (en) A valve arrangement
KR950001967Y1 (en) Hydraulic circuit of lift for car repair
EP2243964A2 (en) Control valve
JP3630379B2 (en) Hydraulic circuit in lift for vehicle maintenance
JPS6363535A (en) Die cushion device in press machine
RU1788412C (en) Method of controlling hydraulic system of vertical motion mechanism of walking beams of heating furnaces
US1435138A (en) Controlling mechanism for fluid-operated tools
JPH017842Y2 (en)
SU835829A1 (en) Hydraulic press control system
SU667430A1 (en) Dump truck body tipping arrangement
KR810002056B1 (en) Stroke controling device for press brake
JPS63240963A (en) Water surface following type fountain device

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19960510

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LI NL PT SE

EL Fr: translation of claims filed
DET De: translation of patent claims
17Q First examination report despatched

Effective date: 19970630

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

ITF It: translation for a ep patent filed

Owner name: INVENTION S.N.C.

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LI NL PT SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980513

Ref country code: LI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980513

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980513

Ref country code: CH

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980513

Ref country code: BE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980513

Ref country code: AT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980513

REF Corresponds to:

Ref document number: 166038

Country of ref document: AT

Date of ref document: 19980515

Kind code of ref document: T

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REF Corresponds to:

Ref document number: 69410283

Country of ref document: DE

Date of ref document: 19980618

REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2116062

Country of ref document: ES

Kind code of ref document: T3

ET Fr: translation filed
REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

Free format text: 80363

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980813

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980813

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19980813

NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19981019

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19981019

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19981019

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 19991001

Year of fee payment: 6

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19991012

Year of fee payment: 6

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19991110

Year of fee payment: 6

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20001020

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010629

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010703

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

REG Reference to a national code

Ref country code: ES

Ref legal event code: FD2A

Effective date: 20011113

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 20051019