US3762165A

US3762165A - Hydraulic elevator apparatus

Info

Publication number: US3762165A
Application number: US00203194A
Authority: US
Inventors: M Takenoshita; F Fujisawa
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1970-12-07
Filing date: 1971-11-30
Publication date: 1973-10-02
Anticipated expiration: 1990-10-02
Also published as: DE2160449A1

Abstract

A hydraulic elevator apparatus having an oil hydraulic variable displacement pump capable of functioning also as an oil hydraulic motor and being arranged so that a pressurized oil is supplied to a hydraulic cylinder by the said oil hydraulic pump to cause ascension of the cage via a plunger, and that the pressurized oil is discharged from the hydraulic cylinder by the said oil hydraulic motor to cause descension of the cage.

Description

United States Patent I [I 1 3,762,165

Takenoshita et al. 1 Oct. 2, 1973 [54] HYDRAULIC ELEVATOR APPARATUS 2,387,777 lO/l945 Stanton et al l87/l7 UX 3,057,160 /1962 Russell et al..., 60/52 HD [751 mentors: Takemshfar Katsuta; 3,126,706 3/1964 Dettinger 60 52 HD Fumio Fujisawa, Mlto, both of Japan [73] Assignee: Hitachi, Ltd., Tokyo, Japan [72] Filed. 1971 Primary ExaminerEdgar W. Geoghegan AttorneyCraig, Antonelli & Hill [21] Appl. No.: 203,194

[30] Foreign Application Priority Data Feb. 26, 1971 Japan 46/9365 [57] ABSTRACT May 17, 1971 Japan." 46/325l9 1 Dec. 7, I970 Japan r. /107573 A hydraulic elevator apparatus having an Oil hydraulic 52 US. Cl /445 60/446 60/479 Variable displacemem Pump capable functioning 187/17 also as an oil hydraulic motor and being arranged so [51] Int. Cl. FlSb 15/18 that a pmssurlzed Oil is Supplied to a hydraulic cylinder [58] Field of Search 60/52 HD 52 vs by Said hydraulic Pump cause ascensim 60/445 446 cage via a plunger, and that the pressurized oil is discharged from the hydraulic cylinder by the said oil hy- [56] References Cited draulic motor to cause descension of the cage.

UNITED STATES PATENTS 2,269,786 1/1942 Rose 187/17 8 Claims, 15 Drawing Figures CA GE Pmaminw'z 3.152.165

SHiET 02 0F 11 INVENTORS M ITSUAKI TAKENOSHITA UN O FUJISAWA I ATTORNEY5 PAIENIEBHB film-2.165

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g gg 2/5) I 32/9 INVENTORS MITSUAK TQENOSHITAfUMIO FUIISAWA C0023, aMtowLQQ 1, H-LQQ ATTORN EYS PATENTEDIIBT 2m SHEET O80F11 INVENTORS M (rsuA Kl TAKENOSHITA Fumo FUJ'I sAwA ATTORN EYS HYDRAULIC ELEVATOR APPARATUS BACKGROUND OF THE INVENTION a. Field of the lnvention The present invention is concerned with a hydraulic elevator apparatus designed to cause ascension and descension of the cage via a plunger by supplying pressurized oil to and discharging same from a hydraulic cylinder.

b. Description of the Prior Art It is usual that conventional ram-type hydraulic elevator apparatuses are designed so that the ascension speed control is performed by the use of an oil hydraulic fixed displacement pump having a constant discharge rate (meaning a discharge volume per revolution), and by bleeding the pressurized oil off by an ascension flow rate control valve, and that the descension speed control is performed not by the use of the oil hydraulic pump but by utilizing the weight of the cage and the plunger themselves and also by the descension flow rate control valve.

Conventional hydraulic elevator apparatuses having the aforesaid flow rate control valves had the disadvantage that, because pressurized oil was discharged from the flow rate control valves, these flow rate control valves underwent a substantial heat generation and accordingly the temperature of the oil was elevated markedly. For this reason, there occurred intensive fluctuations of the oil temperature, which led to a wide change in the viscosity of oil. A change in the viscosity of oil caused a change in the amount of leakage of oil from the oil hydraulic pump, and this in turn led to a change in the flow rate of the oil passing through the flow rate control valves. Such a change in the flow rate of oil due to the change in the oil viscosity meant a change in the velocity of running of the cage caused by the oil temperature, resulting in an increased erroneous position of arrival of the cage at the desired floor level. Thus, the function of an elevator was markedly adversely affected. Furthermore, there are limits to the temperature of oil at which the hydraulic pump can be operated soundly. The limit highest temperature has been accepted to be about 70C. Therefore, in a hydraulic elevator apparatus which was frequently operated, this limit highest temperature was reached during a short period of time, often rendering the operation impossible. In order to prevent the occurrence of: such an inoperable condition of the elevator apparatus; a change in the travel speed of the cage; and an increase in the positional error of arrival of the cage at the desired floor level, it has been the practice to provide a cooling means for the hydraulic power unit. However, the provision of the cooling means led to an increase in the cost of the hydraulic power unit. Also, a cooling means utilizing water as a coolant undesirably caused an increase in the maintenance cost.

On the other hand, in an elevator apparatus using flow rate control valves, cavitation develops at the diaphragm section at the time when the pressure of oil undergoes a change to atmospheric pressure as the pressurized oil passes through the orifice. It is no doubt undesirable that the valve body sustains abrasive damages due to the cavitation which is developed. It is also undesirable that pressure pulsation develops or that annoying noise spreads therearound.

The present invention has been worked out with a primary object of solving the aforesaid problems. This object is attained by the arrangement in which an oil hydraulic variable displacement pump which is also capable of functioning as an oil hydraulic motor is used so that the ascension of the cage is accomplished by supplying a pressurized oil to the hydraulic cylinder from the said pump and that the descension of the cage is effected by leading the pressurized oil contained in the said hydraulic cylinder to the said hydraulic pump to actuate the hydraulic pump to serve as a hydraulic motor, thereby causing the pump-driving electric motor to make regenerative braking action, and also in which the control of the travel speed of the cage is accomplished by the alteration of the discharge volume (meaning the flow rate per revolution) of the said pump. The aforesaid hydraulic elevator apparatus will hereunder be referred to as the pump-controlled hydraulic elevator apparatus."

In a pump-controlled elevator apparatus of the type described, it is important from the aspects of both operation and function that the discharge volume of the pump is controlled automatically and positively. Another object of the present invention, therefore, is to provide a pump-controlled hydraulic elevator apparatus in which the discharge amount of the hydraulic pump is controlled positively and automatically. This object is attained by the arrangement that a cam or a disk for detecting the pump control angle is provided on either the controlling electric motor or on the control shaft of the pump to thereby actuate a cam switch, and that by the cooperation of this switch and a cam switch provided on the vertical travel path of the cage, a series of operations suitable for the desired speed control, as well as the desired positional control of the elevator apparatus can be made feasible.

Still another feature of the present invention lies in the arrangement that those pump controlling means, i.e., control electric motor, cams and cam switches, are combined integrally with the pump to provide a compact pump means for use in an elevator. According to the present invention, an oil hydraulic fixed displacement pump is of either the plunger type or the vane type. These two types of hydraulic pumps produce very little leakage. Therefore, by precision control of only the control angle of the pump, it is possible to attain satisfactory speed as well as positional controls of the pumps. In our efforts to develop a pump-controlled hydraulic elevator apparatus, there arose the problems that there occurred a substantial delay of start at the time of ascension and also that the shock at the time of starting descension was great. These phenomena may be explained as being caused by the following reasons. That is to say, a pilot operated check valve is inserted in the piping which connects the hydraulic pump with the hydraulic cylinder, for keeping the cage in its stationary state. Prior to the start, however, there is a substantial difference in pressure between the hydraulic cylinder side and the pump side relative to the said 'check valve. More specifically, when the flow rate of the pump is rendered nil prior to the start, the pressure on the pump side is much lower than that on the cylinder side at the time of start of ascension, and accordingly, even by increasing the flow rate of the pump by a start command, there is required a considerable length of time before the pressure on the pump side is brought into balance with the pressure on the cylinder side and before the non-return valve is forced open. On the other hand, at the time of descension, the pilot operated check valve is rendered open hydraulically. However, due to the substantially great difference in pressure between both sides relative to the check valve, the pressurized oil is discharged from the cylinder side to the pump side upon opening of the check valve, causing a quick lowering of the cylinder pressure, resulting in the introduction of a shock of start into the cage.

It is, therefore, still another object of the present inventiori to provide a pump-controlled hydraulic elevator apparatus which minimizes both of the afore-said start delay and the start shock. As a means of solution of these inconvenient phenomena, the present invention proposes to set the pressure in that portion of piping which connects the hydro-pump and the pilot operated check valve to a value which is lower than the cylinder pressure but higher than the atmospheric pressure, at the stage prior to starting. By this arrangement, it becomes possible to minimize the differential pressure between the portion of piping on the pump side and the portion of piping on the cylinder side relative to the check valve. Thus, the start delay and the start shock are both markedly diminished. As a means for rendering that portion of piping on the pump side to be pressurized prior to starting, there is the consideration that a small size auxiliary pump is used in addition to the elevator-driving pump. However, if the physical property of the variable displacement pump is utilized to have this pump discharge a very small amount of oil prior to starting instead of being perfectly neutral, i.e., instead of its theoretical flow rate being nil, it is possible to reduce the number of component parts and to thereby provide an apparatus which is inexpensive.

A yet another object of the present invention is to provide a pump-controlled hydraulic elevator apparatus in which the spontaneous lowering in position of the cage when the latter is held stationary for a prolonged period of time is prevented. More specficially, in the apparatus of the prior art which is designed so that the pilot pressure is led from that portion of piping located on the cylinder side, via a solenoid operated directional control valve, to operate the pilot operated check valve, there is produced in the solenoid operated directional control valve a very trifle but unavoidable leakage of oil even where the cage is given a condition of stoppage for control. As a result, there takes place an unavoidable phenomenon that the cage makes a spontaneous slow and gradual descension. As a means to cope with this inconvenient phenomenon, the present invention proposes an elevation of the intra-pipe pressure between the pump and the check valve up to a value required for the pilot operation of the check valve, to thereby utilize the resulting elevated intrapipe pressure as the pilot pressure. According to this proposal, the only factors which take part in the descension of the cage during the period of its stop will be the leakage from the check valve and the leakage from the packing which is used between the cylinder and the plunger. it should be noted, however, that those check valves and packing which are available of late are of superior physical properties such that we may safely conclude that there arises practically no leakage of oil from these two kinds of members. Thus, the use of these two members does not hamper in any way the object of the present invention to prevent the spontaneous descension of the cage while it is in the stationary state. In addition, the elevation of the intrapipe pressure between the pump and the check valve prior to starting serves also not only to the reduction of start delay and start shock but also to the prevention of the aforesaid spontaneous descension of the cage.

A further object of the present invention is to provide a pump-controlled hydraulic elevator apparatus which is free of excessive vibration of its cage. It should be understood that the operation of a pump-controlled hydraulic elevator apparatus is substantially always subjected to changes in speed from the time of start till it is stopped. Thus, there tends to appear excessive vibration in the oil contained in both the piping and the hydraulic cylinder owing to the compression of oil. Since this excessive vibration harms the confortable ride, it is necessary to provide some means for controlling the vibration. As a means for preventing excessive vibration, consideration may be directed first to smoothing of the changes of the flow rate of the pump relative to time. This, however, complicates the control mechanism of the pump and therefore is not advantageous from the viewpoint of cost. The most inexpensive means is the use of a control electric motor which runs at a constant speed to thereby produce a flow rate in proportion to the control angle of the pump. In view of the fact, however, that coefficient of change in the flow rate of the pump, i.e., the differential value of the flow rate relative to time, takes a rectangular waveform relative to time, there is the drawback that vibration develops easily. It is, therefore, the aim of the present invention to provide a pump-controlled hydraulic elevator apparatus which is comfortable in riding even where it utilizes such a simple control system. Other causes for excessive vibration may include that the friction of the packing which is used in the prevention of leakage of oil between the plunger and the cylinder suddenly changes from static friction to dynamic friction at the time of starting, and that when the pilot type check valve which is used for holding the stationary state of the elevator cage is opened quickly, the pressurized oil is discharged suddenly and quickly. Of these two causes, the latter vibration can be decreased by elevating the pressure between the pump and the non-return valve. However, it is quite difficult to render the differ ence between the pressure of the pump and the intracylinder pressure to zero, and therefore, the occurrence of some amount of start shock cannot be helped.

As a means for preventing the aforesaid excessive vibration, the provision of an accumulator on the main route of piping which connects the check valve and the hydraulic cylinder, with the intervention of a diaphragm therebetween is effective. The principle of vibration control by an accumulator is explained that the changes in the pressure within the main piping route in the midst of development of excessive vibration are mitigated either by supplying oil fromthe accumulator to the main piping route or by sucking the oil into the accumulator.

It should be understood, however, that a mere insertion of an accumulator would mean a mere addition of a spring means to the system, and would not give rise to any vibration control effect. Also, the vibration control effect of the accumulator will be lost either, even if the fluid resistance in that portion of piping route which is intended for connecting the accumulator to the main piping route is made excessively great. The resistance of the throttle valve which is provided at the inlet of the accumulator is, as a matter of course, of an optimum value at which the damping effect of vibration of the elevator system can become maximum.

However, the resistance of the throttle valve at the time of starting has to be smaller than that at the time of ordinary changes of speed, for both the ascension and the descension. This is because the intracylinder pressure undergoes a sudden quick change due to a sudden change in the friction of the gasket, and also because the accumulator must behave quickly to mitigate this quick change in the pressure within the cylinder. Moreover, at the time of descension, the pressurized oil contained in the cylinder is jetted out to the pump upon release of the non-return valve as stated previously. Accordingly, the intra-cylinder pressure undergoes a change as sudden and quick as is the change due to the friction of the packing. In order to prevent the shock and excessive vibration due to such severe change, it is necessary to supply oil quickly from the accumulator.

If, however, there is effected a change in speed from the starting to the stoppage of the elevator apparatus without altering the throttle resistance which is held suitable for starting, no sufficient effect of attrition of vibration by the accumulator is obtained other than the time of starting. Especially, at the time of the completion of speed reduction, or in other words, at the time of entering into the operation of landing, the cage would inconveniently exhibits a substantial over-shoot in speed. Since the landing or the floor-arriving operation is small in magnitude, a large overshoot would possibly cause the cage to stop momentarily. This overshoot is one of the phenomena which contribute to uncomfortable riding.

The present invention has been worked out with the purpose also to eliminate the aforesaid problem. To this end, there is provided, on that portion of piping route which connects the accumulator with the main piping route, a throttle which exhibits a small resistance at the time of accerelation and which exhibits a large resistance at the period of operation from the full speed operation till the stoppage. By this arrangement, the throttle resistance of the accumulator is controlled to decrease the shock at the time of starting, and the development of over-shoot which tends to occur at the time of speed reduction is prevented, to thereby improve the comfortableness in transporting passengers on the pump-controlled type elevator.

Other objects, advantages and features of the present invention will become apparent by reading the following description of the preferred embodiments in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of the control circuitry of the pump-controlled hydraulic elevator apparatus showing an embodiment of the present invention.

FIG. 2 is a somewhat diagrammatic representation of the overall construction of cam switches employed in the present invention.

FIG. 3 is a somewhat diagrammatic fragmentary view of same.

FIG. 4 is a chart showing the control angle of rotation of the pump.

FIG. 5 is a schematic representation showing the manner of driving the control electric motor and the speed of the cage, to explain the present invention.

FIG. 6 is an electric circuit diagram for explaining the behavior of an embodiment of the present invention.

FIG. 7 is a main electric circuit diagram for operating an electric motor.

FIG. 8 is hydraulic circuitry, showing another embodiment of the present invention.

FIG. 9 is a somewhat diagrammatic plan view, showing a control means of the oil hydraulic fixed displacement pump of the present invention.

FIG. 10 is a side elevation, with parts broken away, of the control means shown in FIG. 9.

FIG. 11 is a load compensation means for compensating for the changes in level due to changes in load arising during the stationary period of the pumpcontrolled hydraulic elevator apparatus, which is a drawback of the prior art.

FIGS. 12(1) and 12(2) are somewhat diagrammatic electric circuitry for operation, to explain the behavior of the said another embodiment of the present invention.

FIG. 13 is a circuit diagram for the operation of a solenoid brake.

FIG. 14 is a main electric circuit for operating an electric motor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 represents an oil tank. Numeral 2 represents a filter. Numeral 3 represents an oil hydraulic variable displacement pump. Numeral 4 represents an electric motor for driving the pump 3. Numeral 5 represents a control electric motor having reduction gear. Numeral 6 represents a brake for positively holding the control electric motor 5 at its rest position. Numeral 7 represents a disk for detecting the control rotational angle of the pump 3, in which the travel speed of the cage due to the discharge rate of the pump 3 is preliminarily established on this disk 7.

Numerals 8 12 represent cam switches actuated by the disk 7. Numeral 13 represents a casing for accommodating these cam switches 8 l2. Numeral l6 represents a pilot operated check valve. Numeral l7 represents a main piping route for connecting the said pump 3 with the pilot operated check valve 16. Numeral 18 represents a relief valve which is operative so that, in case a high pressure is applied to this main piping route 17, pressurized oil is returned automatically to the tank 1 to be kept under the predetermined pressure. Numeral 19 represents a solenoid operated valve for supplying the pressure of the main piping route 17 to the pilot operated check valve 16 to have this valve behave for the operation of descension of the cage. Numeral 20 represents a cylinder which is operative so that, by supplying pressurized oil to this cylinder 20 and by discharging the oil therefrom, the cage 22 is caused to ascend and descend via a plunger 21. Numeral 23 represents a piping route for connecting the pilot operated check valve 16 with the cylinder 20. Numeral 24 represents an accumulator for controlling the vibration of the cage 22. This accumulator 24 is connected in parallel with the piping route 23 by a piping route 27 having a throttle 25 and a solenoid operated directional control valve 26 and by a piping route 29 having a throttle 28.

FIG. 2 shows a more concrete representation of the cam switches. The arrangement within the cam switch accommodating casing 13 is such that: cam switches 8 and 9 are intended for landing operation, in which the cam switch 8 deals with ascension and the cam switch 9 is assigned for descension; the cam switch 10 is a reference angle detecting cam switch for confirming that the control rotational angle is always at the reference position during the stationary period of the elevator apparatus, whereas cam switches 11 and 12 are intended for causing the cage 22 to effect a predetermined full speed travel, in which the cam switch 1 1 is assigned for ascension and the cam switch 12 deals with descension.

Numerals 39 39 represent bolts for actuating the cam switches to adjust their positions relative to the disk 7. These cam switches 8 12 are comprised of levers 41 assigned to changeover the electric contactors provided within a mold 40 and springs 42 intended for supporting levers 41 as shown in FIG. 3.

Description will hereunder be made on the manner in which the pump 3'is controlled and also on the behavior of the elevator apparatus.

It should be understood that the electric motor 4 for driving the pump 3 is controlled in the same way regardless of whether this motor 3 drives the pump at the time of starting the elevator apparatus or when the elevator apparatus is operated continuously. However, with respect to the behavior which is stated hereunder, description will be made on the instance where the electric motor 4 is rotated always at a synchronous speed. It should be noted that the reference angle 51 of the pump 3 is set in such a way that it is deviated slightly on the positive side as shown in FIG. 4 so that a pressure sufficient for operating the pilot operated check valve 16 even during the rest period of the elevator appraratus, i.e., a pressure less than the cracking pressure (meaning within the range less than the pressure in the cylinder during the stationary period of the elevator apparatus), is always applied to the piping route 17.

ASCEN DING OPERATION Upon the Up" command, a circuit T-UP-DLS- llX,-R is formed because the switch DLS is in its make" state. whereupon, the coil 11X is energized to form a circuit T- 12B- -llB-llX,A-

ll-R. Accordingly, the coil 11 is energized to render the switch 11A on. whereby the control electric motor is driven. As a consequence, the control angle of the pump 3 increases on the positive side so that the discharge rate increases accordingly. Thus, the pressurized oil contained in the piping route 17 forces the check valve 16 open, so that this oil is supplied to the cylinder 20 via the main piping route 23. Since the pressure in the main piping route 17 is substantially equal to that of the cylinder, pressurized oil is supplied to the cylinder 20 without a substantial amount of time delay. The cage 22 is mounted securely on top of the plunger 21. Therefore, the cage 22 will ascend with this plunger 21 by the pressure applied to the plunger 21. As the control angle increases, the cage 22 will gain a gradually increasing travel speed, and thus the so-called acceleration operation of the elevator is performed.

As the control angle assumes its maximum limit, the cam switch 11(KU,) is actuated to form a circuit T- 10A- l1XA-KU,- ll0-R. Along with this, the coil 110 is energized to render the switch 1 10B of the said circuit off. whereby, the switch l l is opened to stop the motion of the control electric motor 5. Along therewith, the discharge rate of the pump 3 becomes constant, so that the cage 22 will make a full speed running at a constant speed.

After this full speed running, the limit switch US provided in the vertical travel path detects the fact that the cage 22 has arrived at a position at which the speed thereof is to be reduced, and a circuit T- 10A- IIXA-US- Ill-R is made. Whereupon, the coil 111 is energized to form a circuit T- llB- 10A- lllA- A- 112B-R, thereby energizing the coil No. 12 to render the switch 12A on. As a consequence, the control electric motor 5 is rotated in the reverse direction, reducing the discharge rate of the pump 3., and thus the cage speed is accordingly reduced.

When the cage 22 gains the landing operation speed (corresponding to the control angle 53 of the pump) for leveling with the floor position, then the cam switch 8(KU is actuated to form a circuit T- 10A- llXAl(U 110A- ll2-R, energizing the coil 112, thereby rendering the switch 112B off. As a consequence, the switch 12A is rendered of and the control electric motor 5 is brought to a halt. Along therewith, the discharge rate of the pump 3 will be a constant small amount, so that a low speed landing operation is performed.

As the cage 22 arrives at the rest position, the limit switch UL for stoppage command which is provided on the vertical travel path makes a circuit T- 10A- llXA-UL 113-R and the coil 113 is energized. Along with this, a circuit T- 11b- 10A- lllA- 113A- 12-R is made so that the switch 12A is again rendered on" to drive the control electric motor 5. With this, the discharge rate of the pump 3 is reduced further.

As the control angle of the pump 3 gains the reference angle 51, the cam switch 10(KD) is actuated, deenergizing the coil#l0 so that a series of ascensionassigned contactors are also deenergized. As a result, the cage 22 is brought to a halt. Throughout this ascension operation, the electromagnetic operated valve 26 is held open only for the acceleration period shown in FlG. 5 and is held closed thereafter.

DESCENDING OPERATION With the DN (Descension) command, the switch ULS which is rendered on forms a circuit T-DN- ULS- l2X,-R. whereupon, the descension-assigned coil 12X is energized to make a circuit T- 12X, A- X-R. Therefore, the coil 120)( is energized to make a circuit T- llB- 120B- 120XA- 12X,A- l2-R. By the energized coil 12, the switch 12A is actuated. The control electric motor 5 is driven in such a way that the control angle of the pump 3 will be located on the negative side. As this control electric motor 5 is started, the electromagnetic operated valve (S) 19 simultaneously causes the pilot pressure to be supplied to the pilot operated check valve 16, rendering this latter valve open. As a consequence, the pressurized oil contained in the cylinder 22 is discharged to the tank 1 via the pump 3, so that the cage 22 descends. As the control angle increases on the negative side, the cage 22 will gain a higher speed, so that the acceleration is performed.

As the control angle of the pump 3 increases towards the negative side and as this control angle assumes its maximum amount 54, the cam switch 12(KD,) is actuated to make a circuit T- 10A (actuated by K0 which is rendered conductive by a slight rotation of the control electric motor 5)- 12XA-KD,- 120-R. Therefore, the coil 120 is energized, rendering the switch 120B of to open the switch 12A, bringing the control electric motor 5 to a halt. Whereupon, the suction rate of the pump 3 is held constant and the cage 22 is caused to descend at full constant speed.

After this full running of the cage 22, the limit switch DS for speed reduction command detects that the cage 22 has arrived to a position for speed reduction, making a circuit T- 10A- 12XA-DS- 121-R. Whereupon, the coil 121 is energized to make a circuit T- 12B- 120A- 12'1A- 122B- ll- R. Thereby, the switch 11A is actuated which, in turn, causes the control electric motor 5 to be driven in the direction opposite to that at the time of acceleration, so that the suction rate of the pump 3 is reduced and the cage speed is reduced accordingly.

When the apparatus makes the landing operation at a control angle 55 of the pump for the leveling with the floor position, the cam switch 9(KD is actuated to make a circuit T- lA- 12XA-KD 120A- l22-R. Wereupon, the coil 122 is energized, rendering the switch 122B off. Along therewith, the switch 11A is opened to stop the motion of the control electric motor 5. The suction rate of the pump 3 is held at a constant small amount, and thus, the cage 22 makes the landing operation.

As the cage 22 arrives at a position at which it stops at the desired floor, the limit switch (DL) for stoppage command provided on the vertical travel path makes a circuit T- 10A- 12XA-DL- 123-R. Thereby, the coil 123 is energized so that a circuit T- 12B- 120A- 121A- 123A- 11 is made. Whereupon, the switch 11A is again rendered on to drive the control electric motor so that the suction rate of the pump is reduced further. As the control angle of the pump 3 gains its reference angle 51, the cam switch (KO) is actuated, de-energizing the coil 10. Whereupon, all ofa series of contactors for descension are also de-energiz'ed, so that the cage 22 is brought to a halt. Along with this, the electromagnetic operated valve 19 (Solenoid S) is rendered off so that the pilot operated check valve 16 is closed. As a result, the cage 22 maintains the stationary state.

It should be understood that, in the acceleration period shown in FIG. 5, operation is performed in such a way that the solenoid valve 26 is held open which is closed upon the completion of acceleration, and that this closed condition is held up to the point of stoppage. By this operation, it is possible to decrease the shock which arises when the non-return valve 16 is opened at the time of starting descension and also to decrease the shock and the excessive vibration which may produce due to the sudden quick change in the friction of the gasket.

Also, by setting the pressure in the main piping route 17 at a level slightly lower than the pressure within the cylinder, it is possible to decrease the start delay and the start shock, and also, from doing so there is obtained a further advantage that this pressure is utilized to operate the pilot operated type non-return valve 16. This procedure constitutes an important matter of the present invention. When it is intended to start the apparatus for ascension at the zero state of the pressure within the main piping route 17, the non-return valve 16 is opened for the first time after the pressure within the main piping route 17 has gained the cylinder pressure, so that the oil is supplied to the cylinder 20. In other words, the time till the pressure within the main piping route 17 reaches the cylinder pressure represents the start delay. By initially setting the pressure within the main piping route 17 at a value close to the cylinder pressure, it is possible to minimize this start delay. With respect to the start for descension, on the other hand, if the pressure in the main piping route 17 is held at zero and if, under this condition, the nonreturn valve 16 is opened by the action of the pilot actuated by the solenoid operated changeover valve 19, the pressure within the cylinder 20 will be discharged to the main piping route 17, causing an abnormal shock to be produced in the cage 22. This phenomenon is caused by the great difference in pressure between the

main piping routes

17 and 23. However, by preliminarily elevating the pressure within this main piping route 17, it is possible to minimize the said shock. In the conventional hydraulic elevator apparatuses, the pilot operation' of the non-return valve at the time of descension was performed by utilizing the pressure within the main piping route 23. However, the leakage, though small, from the solenoid changeover valve could not be avoided, and therefore, when it was intended to keep the elevator stationary for a prolonged period of time, there could arise spontaneous lowering in position of the cage 22. However, by leading this pilot pressure from the main piping route 17, it becomes possible to prevent such a spontaneous lowering in position of the cage 22. As a means of elevating the pressure of' the main piping route 17 to a certain predetermined level, there may be provided separately a small-sized auxiliary pump in place of the hydraulic pump 3. However, by the use of the hydro-pump 3, the use of said auxiliary pump will become unnecessary, and the cost of equipment can be made less expensive accordingly.

FIGS. 8 14 show another embodiment. In FIG. 8, reference numeral 201 respresents a pump unit which is driven, via a coupling 205, by an electric motor 203. Numeral'207 represents a tank. Numeral 209 represents a low pressure main piping route for connecting the said tank 207 with the pump unit 201. Numeral 211 represents a pilot operated type check valve. Numeral 213 represents a high pressure main piping route for connecting the pump unit 201 with the pilot type check valve 211. Numeral 215 represents a high pressure main piping route for connecting the pilot type check valve 211 with a cylinder 217. Numeral 219 represents a plunger. Numeral 220 represents a operating metal member for use in operation. Numeral 221 represents a cage. Numeral 225 represents an accumulator. This accumulator is connected in parallel with the main piping route 215 by.a piping route 224 having a soleniod operated directional control valve 223 and a throttle 222 and by a piping route 228 having athrottle 226. Numeral 227 represents .a sub-pilot operated type check valve which has a cracking pressure lower than that of the pilot operated type check valve. Numeral 229 represents a solenoid changeover valve. Numeral 231 represents a solenoid operated changeover valve for operating the sub-pilot operated type check valve and it has a solenoid 231. Numerals 233 243 represent pilot piping routes. Numeral 245 represents a solenoid for switching the position of the solenoid operated changeover valve 229 to the position 247. Numeral 249 represents a solenoid for similarly switching the position to 251. Numeral 253 represents a relief valve for returning the pressurized oil contained in the main piping route 213 to the tank 207 to thereby lower the pressure down to the predetermined value. Numeral 255 represents means for compensating for the load.

FIGS. 9 and 10 show details of the pump unit 201. Numeral 261 represents the pump body of a hydraulic variable displacement pump. Numerals 262 265 represent arrows indicating the directions in which the pressurized oil is passed. Numeral 266 represents an operating lever of the oil hydraulic fixed displacement pump. Numeral 267 represents an operating shaft of the said pump body 261. Numeral 268 represents a pin. Numeral 269 represents a wheel. Numeral 270 represents a control shaft. Numeral 271 represents an oil seal. Numeral 272 represents a bearing of the control shaft 270. Numeral 273 represents a collar. Numeral 274 represents a holding member of the bearing 272. Numeral 275 represents a driving gear. Numeral 276 represents a follower gear. Numeral 277 represents a chain. Numeral 280 represents a reduction gear. Numeral 281 represents a control electric motor. Numeral 282 represents a solenoid brake.

Numerals

283 and 284 represent arrows indicating the directions of rotation of the wheel 269. The direction of 283 represents ascension, whereas the direction of 284 represents decension. Numeral 285 represents a cam shaft.

Numerals

286 and 287 represent bearings of the cam shaft 285. Numerals 283 294 represent cams. Numerals 295 301 represent limit switches actuated by the cams 288 294. Numeral 302 represents a support for attachment of the limit switches 295 301.

F 1G. 11 is an explanatory illustration of the means for compensating for the load (see the block at 255). Numeral 320 represents a vertical travel path. Numeral 321 represents a rope for detecting the load.

Numerals

322 and 323 represent pulleys. Numeral 324 represents a clutch. Numeral 325 represents a driving shaft. Numeral 326 represents a follower shaft.

Numerals

327 and 328 represent cams.

Numeral

329 and 330 represent limit switches actuated by the

cams

327 and 328. Numerals 331 e 334 represent bearings. A and B represent two adjacent floor levels for the elevator cage to stop at in ascension and descension. Numeral 341 represents a limit switch (USDL) for commanding a reducting in speed of ascention. Numeral 342 represents a limit switch (UL) for commanding the stoppage of the elevator. Numeral 343 represents a limit switch (DSDL) for commanding a reduction in speed of descension. Numeral 344 represents a limit switch (DL) for commanding stoppage. Numeral 345 represents a cam for actuating the limit switches 341 344.

BEHAVIOR OF THE PUMP-CONTROLLED HYDRAULIC ELEVATOR APPARATUS.

Description will hereunder be made on the behavior of the elevator apparatus by referring to FIGS. 8 14. When connected to the power source, there is made a circuit T-EM (b)- 349T(b)- 350X-R to actuate the switch 350x. Upon depression of the on switch, there is formed a circuit '1- 397x (initially (a) is held on)- 352X(b)- 352M-R, and the coil 352M is energized, making a circuit T- 352M(a)- 352X(b)-TRX(b)- 352M-R, and this circuit is self-held. It should be understood that the limit switch 297 is intended for detecting the condition that the pump body 261 is in the reference position, and that since the elevator makes vertical travel from this reference position, this limit switch is always rendered on throughout the stationary period of the elevator, whereas 397x is actuated. At the same time with the self-holding condition of the said circuit, the electric motor 203 is driven by the coil 352M, ready for the arrival of'a command of operation of the elevator apparatus.

ASCENDING OPERATlON Upon depression of the switch for ascension, there is made a circuit T- 352LX(b)-Up(a)- 397(a)- 395X(b)- 352RX-R. As a consequence, the coil 352RX is energized to make a circuit T- 352LX(b)- 352RX(a)- 397X(a)(when 397X(a) is rendered off, 400x is rendered on)- 395X(b)- 352RX-R, and this condition is self-sustained. At the same time therewith, the control electric motor 281 is driven by 352RX, so that the wheel 269 is rotated in the direction of the arrow 283. Along with this, the operation lever 266 moves upwardly, and the pump 261 starts tilting rotation upwardly, sucking the oil in the direction of the arrow 262 and discharging the oil in the direction of the arrow 263. The oil discharged in the direction of the arrow 263 is then supplied to the cylinder via the piping route 213, the pilot operated type check valve 211 and the piping route 215. As a result, the cage 221 makes ascending movement via the plunger 219.

As the angle of inclination produced by the rotation of the pump body 261 reaches the predetermined maximum value, the limit switch 295 is actuated. By this limit switch 295, there is made a circuit T- 397X(b)- 401X(a)- 395(a)- 395X-R, so that the coil 395x is energized, making a circuit T 397X(b)- 401X(a)- 395X(a)- 395X-R, which is self-sustained. At the same time therewith, the circuit T- 3S2LX(b)- 352RX(a)- 400X(a)- 395X- 352RX coil-R is opened. whereupon, the coil 352RX is de-energized, so that the control electric motor 281 is brought to a halt. On the other hand, the discharge rate of the pump 261 becomes maximum, so that the cage 221 effects full speed running. As this cage 221 makes an upward travel and as, accordingly, the speed reduction limit switch 341 provided in the vertical travel path 320 is contacted by the earn 345, the limit switch 341 is actuated. As this limit switch 341 is actuated, there is made a circuit T- 397X(b)- 401X(a)-USDL(a)- USDX coil-R, so that the coil USDX is energized. By the energization of this coil USDX, there is made a circiut T- 397X(b)- 401X(a)- USDX(a)- USDX coil-R, which is self-sustained. At the same time therewith, there is formed a circuit T- 352RX(b)- USDX(a)- 396X(b)- 397X(b)- 352LX coil-R, and the coil 352LX is energized. Upon the energization of this coil 352LX, the control electric motor 281 is driven in the reverse direction, so taht the wheel 269 is rotated in the direction of the arrow 284. As a consequence, the angle of inclination of rotation of the pump body 261 is reduced and accordingly the discharge rate is reduced, so that the cage 221 effect ascension while reducing its speed.

As this speed of the cage 221 which is reduced in the aforesaid manner reaches the landing operation speed, the limit switch 296 is actuated. Upon this actuation of the limit switch 296, there is made a circuit T- 396X-R, so that the coil 396X is energized. Upon this energization of the coil 396X, there is made a circuit T- 397X(b)- 401X(a)- 396X(a)- 396X-R, which is slef-sustained. At the same time with this, the circuit T-352RX(b)- USDX(a)- 396(b)- 397X(b)- 352LX-R is broken, de-energizing the coil 352LX, so that the control electric motor 281 is brought to a halt. Along with this, the discharge rate of the pump body 261 will become constant and small, so that the cage 221 will travel at a low speed, which is the landing operation. The cage 221 thus makes an upward travel at the landing operation speed. During this course of travel, the cam 345 is brought into contact with the limit switch 342 provided in the vertical travel path 320 assigned for commanding stoppage. Whreupon, the limit switch 342 is actuated. With this actuation of the limit switch 342, there is made a circuit T- 397X(b)- 401X(a)-UL(a)- ULX-R, so that the coil ULX is energized. Upon this energization of the coil ULX, there is formed a circuit T- 397X(b)- 401X(a)- ULX(a)- ULX-R, which is self sustained. At the same time therewith, a circuit T- 352PX(b)- USDX(a)- ULX(a)- 397X(b)- 352LX-R is made, so that the coil 352LX is again energized to drive the control electric motor 281. The wheel 269 is rotated further in the direction of the arrow 284, reducing the tilting angle of rotation of the pump body 261 and accordingly reducing the discharge rate thereof. Thus, the cage 221 is caused to land at the landing position B of the vertical travel path 320. Then, the limit switch 297 assigned for detection of the reference position is actuated. Upon this actuation of this limit switch 297, there is made a circuit T- 397(a)- 397X-R, so that the coil 397X is energized. Upon this energization of the coil 397X, the circuit T- 352RX(b)- USDX- ULX- 397X- 352LX-R is opened, de-energizing the coil 352- LX, and thus, the control electric motor 281 stops.

DESCENDING OPERATION Upon depression of the switch DN for descension, there is made a circuit T- 352RX(b)-DN(a)- CX-R, so that the coil CX is energized. With this energization of the coil CX, there is made a circuit T- 352RX(b)- CX(a)- CX-R, which is self-sustained. On the other hand, by this coil CX, there are made the circuits T- CX(a)- CX,-R and T- CX(a)-249 (soldenoid)-R, so that the coil CX and the solenoid 249 are both energized. Upon this energization of the solenoid operated 249, the solenoid directional control valve 229 is switched over to the position 251. On the other hand, there are made, by the coil CX,, a circuit T- CX,(a)-231 (solenoid)-R and another circuit T- 352RX(b)- CX,(a)- 397X(a)- 399X(b)- 352LX-R,so that the directional control valve 231 is actuated and the coil 352LX is energized.

By this changeover valve 231, the pressurized oil contained in the piping route 215 is supplied to the sub pilot-operated check valve 227 via the pilot circuit 233 235 to actuate this valve 227. Then, sequentially, the pressurized oil is supplied to the pilot operated check valve 211 via the pilot circuit 237 239 241 to actuate this valve 211. At the same time therewith, the control electric motor 281 is driven, by the coil 352LX, in the direction opposite to that for ascension. The wheel 269 is rotated in the direction of the arrow 284, moving the link 266 or lever downwardly, which in turn causes the pump body 261 to make a downwardly inclined rotation. Whereupon, the pressurized oil contained within the cylinder 217 is introduced to the pump body 261 via the piping route 215, the pilot operated check valve 211 and the main piping route 213. By sucking the pressurized oil further in the direction of the arrow 264 shown by the dotted line, and by discharging it in the direction of the arrow 265 to return the oil to the tank 207, the cage 22] is caused to make a descension.

As the tilting angle of rotation of the pump body 261 reaches the predetermined amount, i.e., the maximum value on the negative side, the limit switch 299 is actuated. By this limit switch 299, there is made a circuit T- 397X(b)- 400X(a)- 399(a)- 399X-R, and the coil 399x is energized, making a circuit T- 397X(b)- 400X(a)- 399X(a)- 399X-R, which is self-sustained. At the same time with this, the circuit T- 352RX(b)- CX,(a)- 401X(a)- 399X- 352LX-R is opened, de-energizing the coil 352LX, and as a result the control electric motor 281 ceases its motion. On the other hand, the discharge rate of the pump body 261 assumes the maximum amount, and the cage 221 makes descension at full speed.

'As this cage 221 descends at full speed and as the cam 345 contacts the limit switch (DSDL)343 assigned for speed reduction and provided in the vertical travel path 320, the limit switch (DSDL)343 is actuated. By this limit switch (DSDL)343, there is made a circuit T- 397X(b)- 400X(a)-DSDL(a)- DSDX-R, so that the coil DSDX is energized. Upon this energization of the coil DSDX, there is made a circuit T- 397X(b)- 400X(a)- DSDX(a)- DSDX-R, which is self-sustained. Simultaneously with this, a circuit T- 352LX(b)- DSDX(a)- 396X(b)- 397X(b)- 352RX-R is made and the coil 352RX is energized. By this energization of the coil 352RX, the control electric motor 281 is driven in the direction opposite to that for acceleration. The wheel 269 is rotated in the direction of the arrow 283, and the inclination angle of rotation of the pump body 261 becomes smaller, causing the discharge rate to be reduced, so that the cage speed decreases.

As the cage speed decreases in this way and as the speed reaches the landing operation speed, the limit switch 298 is actuated. By this actuated limit switch 298, there is made a circuit T- 397X(b)- 410X(a)- 398(a)- 399X(a)-R, energizing the coil 398X. As this coil 398)( is energized, it is self-sustained by T- 397X(b)- 400X(a)- 398X(a)- 398X(a)- 398X-R. At the same time, the circuit T- 352LX(b)- DSDX- 396X(b)- 397X(b)-R is opened, and the coil 352RX is de-energized, so that the control electric motor 281 is brought to a halt. The discharge rate of the pressurized oil from the pump body 261 to the cylinder 217 is thus rendered small and constant, and the cage 221 descends at the landing operation speed.

As the cage 221 descends at the landing operation speed, and as the cam 354 contacts the limit switch 344 which is provided in the vertical travel path 320 and which is assigned for commanding stoppage, this limit switch 344 is actuated. By this actuated limit switch 344, there is made a circuit T- 397X(b) 400X- (a)-DL(a)- DLX-R, so that the coil DLX is energized. Upon energization of this coil DLX, it is self-sustained by T- 397X(b)- 400X(a)- DLX(a)- DLX-R. At the same time therewith, there is made a circuit T- 3S2LX(b)- DSDX- DLX(a)- 397X(b)- 352RX-R, so that the coil 352RX is energized, and the control electric motor 281 is driven again. The wheel 269 is rotated further in the direction of the arrow 283, while the discharge rate by the pump body 261 is reduced, so that the cage 221 is caused to land at the landing position A in the vertical travel path 320. Sequentially thereafter, the limit switch 297 for detecting the reference position is actuated to make a circuit T- 397(a)- 397X-R, so that the coil 397x is energized. Upon the energization of this coil 397x, a series of contactors assigned for descension are deenergized to close the pilot operated type check valve 211, so that the cage 221 is held at the landing position A.

In the manner stated above, operations between tow adjacent floors A and B have been completed. In case there is no call of either ascension or decension even after the lapse of a certain period of time, the coil TRX is energized in several minutes after the opening of the circuit T- 352RX(b)- 352LX(b)- 3S2M(a)- TRX-R, to thereby open the circuit T- 352M(a)- 3S2X(b)- s 352X(b)- TRX(b)- 352M-R, de-energizing the coil 352M, so that the electric motor 203 is brought to a halt.

The solenoid brake 282 is provided to positively hold the control electric motor 281 at its rest position. This solenoid brake 282 is always de-energized throughout the period in which the coils 352RX and 3S2LX are energized, with its torque being nil.

in case the cage 221 happens to stop at an intermediate position between the two adjacent floors A and B due to interruption of service, or in case the cage 221 happens to stop in the midst of operation, the

limit switches

300 and 301 detect whether the cage was in the course of ascension or in the course of descension.

When the cage 221 stops during the upward trave; (in case the condition such as interruption of service has been removed), there is made the circuit T- 401(a)- 40lX-R,so that the coil 401Xisenergized. Then, in succession thereto, the circuit T- 401X(a)- 352M(b)- DLX(b)- 352X-R is made, and the coil 352x is energized. By this energized coil 352x, its condition is self-sustained by T- 3S2X(a)- 352M(b)- DLX(b)- 352X-R. At the same time therewith, the circuit T- 352RX(b)- 352X(a)- 401X(a)- 397X(b)- 352LX-R is made, thereby the coil 352LX is energized. By this energization of the coil 352LX, the control electric motor 281 is driven in the direction opposite to that prior to its stoppage, reducing the inclination angle of rotation of the pump body 261. As the inclination angle of rotation of the pump body 261 is reduced in this way and as it reaches the reference angle, the limit switch 297 assigned for detection of the reference angle is actuated. By the actuation of this limit switch 297, there is made the circuit T- 397(b)- 397X-R, so that the coil 391x is energized. By the energization of this coil 397x, the circuit T- 352X(a)- 387X(a)-231 (solenoid)-R is made, so that the changeover valve 231 is actuated, causing the pressurized oil contained in the piping route 215 to be supplied to the sub-pilot operated type check valve 227 via the piping routes 233 235, to the reby actuate this check valve 227. whereupon, the pressurized oil contained in the cylinder 217 is discharged to the tank 207 via the piping route 215 and the pilot piping routes 237 239, to thereby cause the cage 221 to descend at a low speed. When the cage 22] aarrives at the limit switch 344 provided in the vertical travel path for commanding stoppage, this limit switch 344 is actuated by the cam 345. By this actuated limit switch 344, there is made the circuit T- 352M(b)- DL(a)- DLX-R, so that the coil DLX is enegized. Upon the energization of the coil DLX, its condition is self-held by T- 352M(b)- DLX(a)- DLX-R. At the same time, the circuit T- 352X(a)- 352M(b)- DLX- 352X-R is opened, and the coil 352x is de-energized. Upon the de-energization of this coil 352x, the circuit T- 352X(a)- 397(a)-231' (soienoid)-R is opened, so that the solenoid 231 is de-energized. Upon the de-energization of this solenoid 231, the sub-pilot operated type check valve 227 is closed, so that the cage 22] is caused to land at the landing position A.

When the cage stops during the descension, the circuit T- 400(a)- 400X-R is made, so that the coil 400x is energized. By the energization of this coil 400x, the circuit T- 400X(a)- 352M(b)- DLX(b)- 352X-R is made, so that the coil 352x is energized. Upon the energization of this coil 352x, its condition is self-sustained by T- #352X(a)- 352M(b)- DLX(b)- 352X-R. At the same time therewith, there is made the circuit T- 352LX(b)- 400X(al- 3S2X(a)- 397X(b)- 352RX-R, and the coil 352RX is energized. By the energization of this coil 3S2RX, the control electric motor 281 is driven in the direction opposite to that prior to its halt. The inclination angle of rotation of the pump body 261 is reduced. As this angle reaches the reference value, the limit switch 297 assigned for detection of the reference angle is actuated. By the ac tuated limit switch 297, there is opened the circuit T- 352LX(b)- 400X(a) 352X(a)- 397X(b)- 352RX-R, so that the coil 3S2RX is deenergized. Owing to the de-energization of this coil 352RX, the control electric motor 281 is brought to a halt. Simultaneously therewith, the circuit T- ii? 352)(- (a)- 397(a)-231' (solenoid)-R is made, so that the changeover valve 231 is actuated. By this actuated changeover value 231, the pressurized oil of the main piping route 215 is supplied to the sub-pilot operated type check valve 227 via the pilot piping routes 233 235, to actuate this check valve 227. As a result, the pressurized oil contained in the cylinder 217 is discharged to the tank 207 via the piping route 215 and the pilot piping routes 237 239, to thereby cause the cage 221 to descend at a low speed. As the cage 221 arrives at the stoppage command limit switch (DL)344 provided in the vertical travel path 320, the limit switch 344 is actuated by the cam 345. Upon the actuation of this limit switch (DL)344, there is made a circuit T-No. 352M(b)- DLX-R, so that the coil DLX is energized. By this energization of the coil DLX, its condition is selfsustained by T- DLX(a)- DLX-R. DLX(a)- DLX-R. At the same time therewith, the circuit T- 352X(a)- 352M(b)- DX- 352X-

Claims

1. A pump-controlled hydraulic elevator apparatus arranged that a cage is caused to make vertical movements via a plunger by the use of a pressurized oil conducted to and from a hydraulic cylinder, comprising: oil hydraulic variable displacement pump means driven by motor means, a check valve means, said pump means and said check valve means being disposed in a piping route connecting said cylinder with an oil tank at intermediate sites therealong for the conduction of oil to and from said cylinder, and control means for regulating both the discharge rate and the suction rate of the said pump to control the discharge of the pressurized oil directly to said cylinder from said oil tank and to control the suctioning of the pressurized oil directly from said cylinder to said oil tank, thereby causing vertical movements of the cage via the plunger.

2. A pump-controlled hydraulic elevator apparatus according to claim 1, in which: said control means comprises a control electric motor having an operating shaft for regulating the discharge rate and the suction rate of said pump, the apparatus further comprises a rotary member rotated in accordance with the rotation of said control electric motor, and limit switch means provided at a position corresponding to a position of said rotary member, said limit switch means being actuated in accordance with the amount of rotation of said rotary member to thereby control said control electric motor.

3. A pump-controlled hydraulic elevator apparatus according to claim 1, in which: means is provided for elevating the pressure within the main piping route connecting said pump with said check valve means up to a predetermined pressure which is lower than the cylinder pressure during the rest period of the cage.

4. A pump-controlled hydraulic elevator apparatus according to claim 3, in which: means is provided for maintaining the control angle of said pump on the positive side during the rest period of the cage.

5. A pump-controlled hydraulic elevator apparatus according to claim 3, in which: the apparatus further comprises a solenoid operated directional control valve at an intermediate site in the main piping route connecting said pump with the said check valve means, and a branch piping route coupled to said check valve means, whereby, at the time of descension of the cage, said solenoid opErated directional control valve is operated to lead the pressurized oil contained in the main piping route to said check valve means to actuate the said check valve means to perform an opening action.

6. A pump-controlled hydraulic elevator apparatus according to claim 1, in which the apparatus further comprises: an accumulator provided in the piping route connecting said check valve means with the hydraulic cylinder via a throttle having a small resistance at the time of acceleration operation and having a large resistance during the period from full speed operation till the stoppage of the apparatus.

7. A pump-controlled hydraulic elevator apparatus according to claim 6, in which: said accumulator and said main piping route are connected together via a parallel piping circuit comprised of a first piping route having a throttle and a second piping route having a throttle and a solenoid operated valve, and means is provided for controlling the connection between the accumulator and the main piping route via said first and second piping routes for the acceleration operation and for closing the connection via said second piping route for the period of operation from the full speed operation till the stoppage of the apparatus.

8. A pump-controlled hydraulic elevator apparatus according to claim 1, in which said apparatus further comprises: a pulley rotated via a rope in accordance with the vertical movements of the cage, detecting means adapted to be coupled to said pulley only when the cage is at rest for detecting spontaneous upward and downward movements of the cage during the stationary period of the cage, said control means including means controlling the discharge of the pressurized oil to the cylinder and controlling the suctioning of the pressurized oil from the cylinder in response to said detecting means.