US3687237A - Electrohydraulic hoist with mechanical backstop - Google Patents

Electrohydraulic hoist with mechanical backstop Download PDF

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US3687237A
US3687237A US82385A US3687237DA US3687237A US 3687237 A US3687237 A US 3687237A US 82385 A US82385 A US 82385A US 3687237D A US3687237D A US 3687237DA US 3687237 A US3687237 A US 3687237A
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load
valve means
valve
actuator
lever
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Uberto Capra
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    • 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
    • F15B21/08—Servomotor systems incorporating electrically operated control means

Definitions

  • ABSTRACT A hoisting system particularly for automotive vehicles, includes a single command lever (17) coupled with a three-position rotary distributing valve l6) and a two-position slide valve (13), the former serving to select one of three modes of operation (up, down or lock”) whereas the latter responds to a shifting of the lever between an otf and an on" position.
  • a hydraulic pump (7) works into a high-pressure line with a first branch leading to a hoisting cylinder (1) for elevating the 10M and with a second branch traversing the two valves in series, this latter branch having an outlet terminating at a set of latching cylim ders (5) whose pistons bear upon spring-loaded detents (4) for arresting the load at a selected level of elevation in the "lock" position of the rotary distributor.
  • the connection between the command lever and the slide valve includes a lost-motion coupling (17', 18) whereby in an intermediate shifting position, in which the lever is stopped in the up" position of the distributor, the slide valve remains closed while an electric switch (25) is actuated to start the pump motor (6) which operates until the lever is restored or the motor circuit is broken by a limit switch (24) tripped at the top of the hoisting stroke.
  • Another switch (29) is closed momentarily upon e of the rotary distributor into or out of its "lock” position to establish an alternate energin'ng circuit for the pump motor which raises the load to release the detents (4) if en, this alternate circuit including a further switch (28) for stopping the pump motor after the load has risen a short distance above its locking level.
  • My present invention relates to a fluid-operated hoist for raising and lowering a load, e.g. an automotive vehicle, under manual control with the aid of an electric switching circuit.
  • the general object of my present invention to provide an improved and virtually foolproof electrohydraulic (or possibly electro-pneumatic) control system for the purpose set forth, particularly for a heavy-duty hoist requiring mechanical arresting by suitable backstops at one or more predetermined levels.
  • a more specific object is to provide a control system of this type utilizing but a single manual actuator for the different operations of starting, stopping and locking as well as for determining the sense of motion (up or down).
  • the system upon a setting of the first valve (referred to hereinafter as a distributor) to any of its various operating positions such as up, “down” or lock, the system will remain inoperative until a command lever or equivalent actuator has been shifted from an off" position to an "on” position with concurrent displacement of the second valve (referred to hereinafter as a controller).
  • a controller concurrent displacement of the second valve (referred to hereinafter as a controller).
  • a lost-motion coupling between the command lever and the controller enables the latter to remain in its blocking position as the lever is moved into its intermediate position; this motion is advantageously limited by indexing means such as an indented stop plste with a relatively shallow notch engaged by the lever in the up position and two relatively deep notches engaged by the lever in the two other positions of the distributor, these deeper notches permitting a shifting of the controller as the lever is moved fully into its "on" position.
  • any untimely shifting of the controller may be prevented by a hydraulic holding circuit responsive to operation of the pump motor.
  • the two degrees of freedom of the command lever serving for the independent displacement of the distributor and the controller, advantageously allow a swinging of the lever about an axis and a translation thereof parallel to that axis, the two valves being then provided with a rotatable and slidable valve body, respectively, entrainable by the lever.
  • the rotary valve body forms part of the three-position distributor whereas the slidable valve body is included in the twoposition controller.
  • the notched stop plate aside from determining the extent of the lever shift in the various operating positions of the distributor, also prevents a swinging of the lever in its intermediate and "on" positions so that the setting of the distributor cannot be changed until this lever is restored to normal and hydraulic pressure is positively cutoff. Even if the lever is held in its shallow notch, the motor circuit is automatically interrupted by a limit switch as soon as the load reaches its top position. Other switches in that circuit, described in detail hereinbelow, serve to raise the load a small distance above its selected level of elevation preparatorily to a release of the previously engaged detent means; one of these latter switches, therefore, may be tripped by the command lever upon rotation of the distributor into or from its lock" position.
  • FIG. 1 is an overall view of a hoisting system embodying my invention, with an elevator shaft shown in sectional elevation and with the associated electrohydraulic control means illustrated somewhat diagrammatically;
  • FIG. 2 is a diagram of the hydraulic circuit of the system of FIG. 1;
  • FIG. 3 is a diagram of the associated electric circuit.
  • the system shown in FIG. 1 comprises a frame forming an elevator shaft for a platform 101 to be used, for example, in the raising and lowering of automotive vehicles between different levels (e.g. floors of a parking garage).
  • Platform 101 is suspended from a plunger 102 whose head is received in a vertical cylinder 1 at the top of frame 100.
  • the interior of cylinder 1 is divided by the plunger head into an upper compartment 1', communicating with a conduit 9', and a lower compartment l communicating with a conduit 9'
  • the frame 100 includes several uprights 3 (only one shown) with recesses or slots 3" separated by solid portions 3'. Each of these uprights 3 co-operates with a respective detent member 4 designed to form a mechanical backstop for the load 10] at any selected level.
  • Member 4 is a generally triangular latch pivoted at 4' on an extension of platform 10] and urged by a spring 4" in a sense (here counterclockwise) tending to maintain the latch disengaged from the recessed upright 3.
  • a hydraulic cylinder 5, also carried on platform 101, has a piston rod 50 bearing from below upon the latch 4 so as to tend to swing the latter in the opposite sense (clockwise), i.e. into engagement with an aligned slot 3", upon a raising of the piston by hydraulic fluid admitted to that cylinder.
  • the piston rod 5a could also be linked with the latch 4 in order to withdraw it from the slot when the detent is to be released, thus supplementing or replacing the spring 4".
  • a switch 28 preferably of the microsensitive type, is also mounted on platform 101 so as to co-operate with the solid portions 3' and slots 3" of upright 3, this switch being closed when the latch 4 is in its locking position (full lines) but being open when the latch is withdrawn and confronts one of the slots 3" in a position ready for engagement (dot-dash lines).
  • the position of the camming roller of switch 28 is so chosen that this roller steps off the upper edge of a slot 3" when the descending latch 4, swung inwardly by the piston rod 5", approaches the lower edge of that slot; switch 28 remains closed whenever the latch 4 adjoins a solid portion 3', opening as soon as the latch clears that solid portion to an extent sufficient to enable its locking engagement with the upright 3.
  • Platform 101 further carries a limit switch 24 which coacts with a bevel 24' near the top of another upright 24" rigid with frame 100.
  • Limit switch 24 which is normally closed, thus opens whenever the load 101 reaches its uppermost position illustrated in dot-dash lines.
  • a bevel 101' at the underside of platform 101 coacts with the end 18' of a horizontally shiftable rod 18, forming part of a slide valve 13, whenever the platform descends to its bottom position.
  • the opposite end of rod 18 forms a lost-motion coupling with a sleeve 17' at the lower end of a command lever 17 topped by a knob 20.
  • Lever I7 is shiftable in axial direction of rod 18 (arrow A) and swingable about the rod axis (arrow B), sleeve 17' being also coupled with a splined shaft 19 of a rotary valve 16.
  • Lever l7 fits into any of three notches 41, 42, 43 of a curved stop plate 40 defining three distinct operating positions I (DOWN), II (UP) and III (LOCK) for the rotary valve 16 which acts as a fluid distributor as more fully described hereinafter with reference to FIG. 2.
  • the three notches 41-43 of plate 40 are of unequal length, notch 42 being shallower than the other two so that a shifting of lever 17 into that notch will not displace the nonrotatable but axially slidable rod 18 in view of the play afforded by its lost-motion coupling with sleeve 17'.
  • lever 17 is aligned with either of the two other notches 41, 43, such a rightward shift does not operate the switch 25 but, in view of the greater depth of these notches, allows the rod 18 to be axially entrained (arrow a) so that its tip 18 projects into the path of bevel 101' of platform 101. Since the platform can descend only in the DOWN position (I) of the distributor 16, for reasons that will presently become apparent, the arrival of the platform at the bottom of its travel will automatically restore the rod 18 to normal and will also force the lever 17 back toward the left if it had been inadvertently held in its ON position by the operator. In position III (LOCK), lever 17 is indexable in an undercut of notch 43, as shown.
  • a further switch 29 has a pair of normally open contacts which are momentarily closed by a projection 22 on lever 17 whenever that lever is swung from distributor position II to position III or vice versa.
  • Switch 29 controls, in a manner to be explained, the raising of platform 101 preparatorily to a release of latch 4 from its locking position.
  • FIG. 2 shows details of the structure of the two valves l3, l6 and of the associated hydraulic circuit.
  • Valve 13 acting as a hydraulic controller, has a slidable body 13' rigid with rod 18 and a spring 13" urging that body and rod toward the left, i.e. into the retracted position of FIG. 1 in which the connection between two ports M, M" in the valve housing is interrupted.
  • Port M is linked via a conduit 15' with a port M in the housing of the rotary valve 16, serving as a hydraulic distributor, in which a valve body 16' is movable between three positions designated I, II and III in conformity with the corresponding designations on the stop plate 40 of FIG. 1.
  • a conduit 5' extends to a set of four latching cylinders 5 in parallel, each of these cylinders being associated with a respective detent 4 (FIG. I) positioned, for example, at the four corners of platform 101.
  • the piston rods 5a emerging from these cylinders have heads 5b under downward pressure from respective loading springs 5c, these springs opposing the hydraulic pressure generated in conduit 5' when the two ports M and C are interconnected in distributor position Ill.
  • the hydraulic fluid (oil) is drawn from a reservoir or sump 9, via a filter 8, by a pump 7 whose output line 15 includes a CHECK valve 10 and terminates at port M", a branch I4 of this line from a junction 14' upstream of valves l3, 16 leading to the lower port of cylinder 1 (FIG. I) by way of pipe 9" with interposition of a check valve 2 in parallel with a throttle valve 21.
  • the effect of the valve combination 2, 2 is to allow free influx of oil into cylinder 1 but to retard the discharge of the oil from that cylinder, thereby slowing the descent of the load 101.
  • bypass 11 leading through an overflow valve 11 normally pressure would closed by a spring 11'' but adapted to be forced open by excessive fluid pressure in the output of pump 7.
  • Another bypass 12 extends from output line 15 to the right-hand end of the valve housing of controller 13 in order to place the valve body 13' thereof under a hydraulic holding pressure, preventing a shifting to its open position whenever the pump 7 is operated by an associated drive motor 6. Since this motor goes into action whenever the switch 25 (FIG. I) is closed upon entry of lever 17 into notch 42, this holding pressure would prevent a full shifting of the lever to its ON position even if the notch 42 had the same depth as notches 41 and 43.
  • the upper compartment 1' of cylinder 1 (FIG. I) communicates via pipe 9' with reservoir 9.
  • distributor position I oil entering the conduit upon the opening of controller 13 is allowed to pass to an outlet port R leading to the sump 9 through a drain pipe 15''.
  • Conduit 5 thenalso communicates with the sump via an outlet port R and a drain pipe 5".
  • port M is cut off while port C still communicates with outlet R
  • distributor position Ill port M is connected not only to port C leading to cylinders 5 but also to a supplemental outlet port R; from which a drain pipe 23' extends to reservoir 9 through a preferably adjustable throttle valve 23.
  • the energizing circuit of motor 6, shown in FIG. 3, includes a source 31 of alternating current which may be a threephase network but, for simplicity, has been shown as comprising only one grounded and one ungrounded bus bar, the latter carrying a high voltage of, say, 220V (RMS) sufficient to operate the heavy-duty pump motor.
  • the live bus bar of network 31 is connected to a field winding of that motor, which may be of the squirrel-cage type, by way of a front contact and armature 26' of a relay 26 in series with the winding of an overload relay 27 having a back contact and armature 27' in the operating circuit of motor relay 26.
  • This operating circuit includes the contacts of the two aforedescribed switches 24 and 25 in series with the secondary winding of a transformer 32 whose primary winding is connected across the power supply 31, in series with a fuse 33, and which serves to step down the voltage of that power supply to a relatively low level of, say, 48V. It will be understood that the system may also include a master switch, not shown, for removing power from both the motor 6 and the transformer 32.
  • An alternate energizing circuit for motor relay 26 includes an armature 30" of an ancillary relay 30 bridging the two switches 24 and 25, relay 30 also having a holding armature 30' in series with the contacts of switches 24 and 28.
  • Switch 29 when closed momentarily upon rotation of the distributor 16 (FIGS. 1 and 2) into or out of its locking position III, connects the winding of relay 30 across the secondary of transformer 32 by way of switches 24 and 28, both these switches being closed in the load position shown in full lines in FIG. 1.
  • the procedure is basically the same with the load starting from either its bottom position or some intermediate level.
  • platform 101 descends until valve body 13' is restored to its closed position by a leftward movement of lever 17 or by the action of bevel 10] upon rod 18; if the mechanical shutoff 101', 18' were not present, the descent would be eventually halted by the platform coming to rest on the foundation.
  • valve body 13' prevents a further descent of the unlatched platform by blocking the discharge of oil from conduit 14.
  • Relay 30 thereupon looks over its holding armature 30, independently of switch 29 but in series with switches 24 and 28, thereby completing the energizing circuit of motor relay 26 via its armature 30".
  • Motor 6 now operates as before and drives the pump 7, thereby immobilizing the valve body 30' in its blocking position so that lever 17 cannot be fully inserted into notch 43 while the motor is running.
  • this roller is cammed outwardly to open the switch whereby relays 30 and 26 release, thus stopping the motor.
  • Controller 13 then opens the path between ports M" and M whereby the oil in line 15, which is under high pressure from the loaded plunger 102 in cylinder 1, i'schanneled from port M on the one hand to conduit .via port C and on the other hand to conduit 23' via port R With a portion of the oil returning to sump 9 through throttle valve 23, another portion acts upon the pistons 5b of latching cylinders 5 (which advantageously are of identical construction) so as to pivot the associated detents 4 into aligned slots
  • the operator must await the stopping of pump 7 by the de-energization of relay 30 through the opening of switch 28 (or possibly 24) as platform it)! rises sufficiently to allow the springs 4" to retract the latches 4 from the engaged slots 3". Thereafter, the lever can be shifted into its ON position to initiate a controlled descent of the load as described above.
  • the one-way throttle 2,2 should be disposed as close as possible to the lower port of cylinder 1 so as to minimize the risk of a break in pipe 9" which could rapidly drain the lower compartment 1".
  • switch 28 could also be of the type which opens when confronting 'a recess and closes when in contact with a solid portion or tooth of a rack-like structure similar to upright 3, with a shaping of the rack generally complementary to that of this upright.
  • limit switches individually associated with the several detents 4 and their uprighm 3 may be serially interconnected to assure a more accurate positioning of the platform.
  • the limit switch 24 also need not be tripped by a cam 24' on the elevator shaft (or, if stationary, by a similar cam on the platform 101) but could be actuated by any mobile element mechanically coupled with the load, again with proper allowance for possible elongation of cables and the like used in the transmission of motion.
  • the latches 4 are merely representative of a variety of detent members (e.g. wedges) hydraulically controllable with the aid of valves 13 and 16.
  • detent members e.g. wedges
  • a hoisting system comprising:
  • fluid-operable elevating means for raising and lowering a load
  • fluid-operable detent means mechanically coupled with said load for arresting same at a selected level
  • a source of high-pressure fluid provided with an output line leading to said elevating means and to said detent means;
  • first valve means in said output line for controlling the admission of fluid from said source to said elevating means and detent means
  • second valve means in said output line in tandem with said first valve means for selectively blocking and unblocking the fluid flow to the latter;
  • said actuator being swingabie about an axis and shiftable parallel to said axis, one of said valve means having a rotatable valve body coupled with said actuator for rotative entrainment only, the other of said valve means having a slidable valve body coupled with said actuator for sliding entrainrnent only;
  • said first valve means having a first operating position for lowering the load, a second operating position for raising the load and a third operating position for actuating said detent means
  • said second valve means having an open position and a closed position for respectively unblocking and blocking the fluid flow to said first valve means
  • said output line having a first branch including said first and second valve means and a second branch leading to said elevating means from a junction upstream of both said valve means for actuating said elevating means in the absence of a discharge path therefor established by said first branch in the first operating position of said first valve means and the open position of said second valve means.
  • a system as defined in claim 1 wherein the coupling between said actuator and said second valve means includes a lost-motion connection for respectively closing and opening said second valve means in one limiting position and in another limiting position of said actuator while keeping said second valve means closed in an intermediate actuator position between said limiting positions, said source including pump means with a motor and an energizing circuit for said motor provided with switch means operable by said actuator in said intermediate position to turn on said motor.
  • said detent means comprises a spring-loaded latch member displaceable by fluid pressure into a locking position upon said Em and second valve means respectively occupying said third and open positions, said first valve means establishing a substantially unrestricted fluid-return path for said detent means in said first and second positions and a throttled return path therefor in said third position.
  • said detent means further comprises an upright with vertically spaced recesses engageable by said latch member at different levels of elevation of said load, said member being urged by its spring force into disengagement from a recess engaged thereby upon a raising of the load above the corresponding level, said energizing circuit including contact means for energizing and de-energizing said motor independently of said switch means.
  • said contact means includes a first set of contacts positioned for momentary closure by said actuator upon movement of said first valve means between said second and third operating positions thereof, said contact means further including a second set of contacts positioned for closure under the control of said elevating means in OK- level positions of said load.
  • said energizing circuit further includes a normally closed limit switch openable under the control of said elevating means in a top position of said load for deactivating said pump means.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Invalid Beds And Related Equipment (AREA)
US82385A 1969-10-21 1970-10-20 Electrohydraulic hoist with mechanical backstop Expired - Lifetime US3687237A (en)

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US (1) US3687237A (enrdf_load_stackoverflow)
AT (1) AT312206B (enrdf_load_stackoverflow)
ES (1) ES381864A1 (enrdf_load_stackoverflow)
FR (1) FR2057773A5 (enrdf_load_stackoverflow)
GB (1) GB1303487A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5727657A (en) * 1995-01-31 1998-03-17 Inventio Ag Apparatus for blocking elevator car travel
US6481534B1 (en) * 2001-08-27 2002-11-19 Otis Elevator Company Apparatus for maintaining adequate overhead space for car top mechanics in elevator systems
CN115929744A (zh) * 2022-11-16 2023-04-07 青岛海琅智能装备有限公司 一种硫化机后充气装置气动控制安全系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113251012A (zh) * 2021-06-04 2021-08-13 萨驰智能装备股份有限公司 一种防爆液压系统及轮胎硫化机

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1189251A (en) * 1915-02-11 1916-07-04 Gilbert A Harden Mechanism for actuating the reversing mechanism of locomotives.
US2130618A (en) * 1936-09-03 1938-09-20 Westinghouse Air Brake Co Fluid pressure motor and locking means therefor
GB497999A (en) * 1937-06-02 1939-01-02 Escher Wyss Maschf Ag Device for the hydraulic control of the blades of screw propellers, blowers and the like
US2711270A (en) * 1950-07-21 1955-06-21 John E Smith S Sons Company Meat cutting machine
US3251278A (en) * 1964-12-16 1966-05-17 Robert H Royster Fluid pressure actuator with fluid pressure controlled locking means

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1189251A (en) * 1915-02-11 1916-07-04 Gilbert A Harden Mechanism for actuating the reversing mechanism of locomotives.
US2130618A (en) * 1936-09-03 1938-09-20 Westinghouse Air Brake Co Fluid pressure motor and locking means therefor
GB497999A (en) * 1937-06-02 1939-01-02 Escher Wyss Maschf Ag Device for the hydraulic control of the blades of screw propellers, blowers and the like
US2711270A (en) * 1950-07-21 1955-06-21 John E Smith S Sons Company Meat cutting machine
US3251278A (en) * 1964-12-16 1966-05-17 Robert H Royster Fluid pressure actuator with fluid pressure controlled locking means

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5727657A (en) * 1995-01-31 1998-03-17 Inventio Ag Apparatus for blocking elevator car travel
US6481534B1 (en) * 2001-08-27 2002-11-19 Otis Elevator Company Apparatus for maintaining adequate overhead space for car top mechanics in elevator systems
CN115929744A (zh) * 2022-11-16 2023-04-07 青岛海琅智能装备有限公司 一种硫化机后充气装置气动控制安全系统

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AT312206B (de) 1973-12-27
GB1303487A (enrdf_load_stackoverflow) 1973-01-17
ES381864A1 (es) 1972-11-16
FR2057773A5 (enrdf_load_stackoverflow) 1971-05-21

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