DE102008034624A1 - Method for technical testing of hydraulic elevator, involves determining maximum pressure in system, where static pressure is determined for elevator car which is loaded with load, and dynamic pressure is determined for elevator car - Google Patents

Abstract

The method involves determining maximum pressure in a system. The static pressure is determined for an elevator car which is loaded with a load in the system. The dynamic pressure is determined for the elevator car which is loaded with the load during an upward drive.

Description

The Invention is in the technical field of conveyor and elevator technology and relates to improved methods of technical testing of Hydraulic lifts, especially the exam the function and effectiveness of the fall-off correction.

State of the art

Of the Drive hydraulic lifts consists of at least one usually electrically operated hydraulic pump and a control block that includes the valve system, and a or more hydraulic cylinders, which perform the lifting work. To high capacity to reach two or more parallel-acting lift (n = 2, 3, ...) provided be. Lift can be arranged symmetrically on the left or right next to the car. It will as well between direct and indirect elevators: the rule is a direct acting lifter for central or off-center Car support; the suspension ratio is thereby i = 1 (1: 1 suspension). For indirectly acting lifts with, for example, off-center car suspension, the suspension ratio is i = 2 (2: 1 suspension). A symmetrical arrangement of two lifters (tandem arrangement, n = 2) is possible with both the indirect and the direct design.

The Lift can be executed one, two or three stages; but they are always single action; Hubarbeit and performed only in upward drive of the car. A controlled downhill drive must therefore be determined by the weight of the car or the car guaranteed be. In some cases is additional a weight balance, z. B. counterweight available. Usually then only a part of the weight of the car is compensated, so the downhill drive still reliable can be realized. For the uphill drive are therefore regularly high operating pressures and high drive power of the pump required.

Around to ensure unhindered entry and exit or loading and unloading is a reliable one level position the car at all stops and under all load conditions (empty or load with rated load) required (high stopping accuracy). If the car is loaded, exercises the weight of the load over the piston of the jack additional Pressure on the hydraulic system off. As a result of the load-related increase in pressure it comes, mainly because of the flexibility of walls and Seals and the compression of residual air quantities in the hydraulic system, to a greater or lesser drop in the loaded car from the original one Position of the unloaded state. For indirect hydraulic Drives with suspension cable suspension occurs in addition an elongation of the suspension cables. Next, there is a risk that through Pressure and hydraulic fluid losses At leaking valves, pipe connections and seals occur (Leakage). These causes lead to an uncontrolled sinking of the car from the originally intended Hold.

The load- and leakage-related drops should be compensated by a correction system the so-called Absinkverhinderungseinrichtung be compensated. The hydraulic pump must be capable of loading Car or leakage occurring volume reduction on the pressure side (Lift side) of the system by recharging hydraulic fluid to compensate.

• 1. Das Druckbegrenzungsventil muss rechtzeitig ansprechen.
• 2. Die Ansprechgrenze des Druckbegrenzungsschalters muss ermittelt werden.
• 3. Die Ansprechgrenze des Druckbegrenzungsventils der Handpumpe muss ermittelt werden.
• 4. Die Wirksamkeit der Absinkverhinderungseinrichtung bei ordnungsgemäß eingestelltem Druckbegrenzungsventil und mit Nutzlast beladenem Fahrkorb muss geprüft werden.
• 5. Die Wirksamkeit der Rohrbruchsicherung muss geprüft werden.

For technical verification of the sufficient effectiveness of the Absinkkorrektursystems and the lifting capacity of the elevator suitable characteristics must be determined regularly. In addition, the sufficient function of the pressure limiter provided in the hydraulic system must be ensured. This is usually in the form of a pressure relief valve, which vents the pressure side of the hydraulic system when an upper limit pressure (set pressure) is exceeded in order to protect the components in the event of blockage and to prevent bursting. The Technical Guidelines for Lifts, TRA 102, Section 3.2.5, describe the requirements for testing hydraulic lifts:

• 1. The pressure relief valve must respond in good time.
• 2. The response limit of the pressure limiting switch must be determined.
• 3. The response limit of the pressure relief valve of the hand pump must be determined.
• 4. The effectiveness of the anti-sag device with properly adjusted pressure relief valve and payload loaded car must be checked.
• 5. The effectiveness of the pipe burst safety device must be checked.

task

The pre-known in the known and required test procedure for testing the Absinkverhinderungseinrichtung See loading the car with the prescribed payload is very complex and time-consuming. There is a desire to provide an improved engineering test method that is easier to perform, which results in more accurate and reliable results and, above all, can avoid loading the car with payload. The technical problem underlying the invention was to provide such an improved and simplified method for the technical inspection of hydraulic elevators.

The technical problem is solved primarily by a (test) method, wherein the total pressure, consisting of static and dynamic pressure components, hereinafter referred to as the dynamic pressure for a loaded with rated load car in uphill p_dyn_Last is determined and this with the maximum in the system occurring pressure p_max, which corresponds in particular to the response pressure of the pressure limiter / pressure relief valve p_DBV, is compared. Is the inequality (test criterion): p_dyn_Last <p_max Fulfills. That is: Is the sum of all statically and dynamically in the hydraulic system in unfavorable conditions, that is, when driving up and in the area of the top floor / stop, always less than the maximum pressure that can be applied by the hydraulic pump, is a sufficient function of Absinkverhindernseinrichtung guaranteed. Under p_dyn_Last is understood as the maximum occurring at nominal load loaded car in upward travel in the system dynamic pressure. It is understood that this takes the largest values when driving up in the uppermost stop.

According to the invention, it is provided that p_dyn_last is calculated from the static pressure taking into account the dynamic factor γ. The method according to the invention contains at least the steps of: determining the maximum pressure p_max, in particular p = DBV; Determining, that is to say preferably measuring, the static pressure p_stat_Last and calculating the dynamic pressure for a nominal load loaded car in upwards travel p_dyn_Last from: p_dyn_Last = γ · p_stat_load

mit:

p_tot_auf

= dynamischer Gesamtdruck bei Aufwärtsfahrt,

p_stat

= statischer Druck im System bei Fahrkorb in oberer Halteposition;

bevorzugt nach:

mit:

c_auf

= mittlere Geschwindigkeit des Fahrkorbs in Aufwärtsfahrt,

ρ

= Dichte des Hydraulikfluids,

Σζ_auf

= Summe der Widerstandsbeiwerte bei Aufwärtsfahrt

In this case, the invention preferably provides for min that this dynamic factor γ is determined via the sum of the drag coefficients during the upward travel. The dynamic factor γ is preferably determined according to the following formulas:

With:

p_tot_auf

= dynamic total pressure when driving upwards,

p_stat

= static pressure in the system when the car is in the upper holding position;

preferably after:

With:

c_auf

= average speed of the car in upwards travel,

ρ

= Density of the hydraulic fluid,

Σζ_auf

= Sum of drag coefficients for uphill travel

The term ρ · c_in ^2/2 designates the kinetic pressure component p_kin in the system during upward travel.

mit:

p_tot_auf

= mittlerer Gesamtdruck bei Aufwärtsfahrt,

p_hydrostat

= hydrostatischer Druckanteil des Hydraulikfluids (p_hydrostat = ρ·g·h),

p_Last

= statischer Druckanteil der Nennlast.

Further preferably, the sum of the drag coefficients is calculated when driving upwards to:

With:

p_tot_auf

= average total pressure when driving upwards,

p_hydrostat

= hydrostatic pressure component of the hydraulic fluid (p_hydrostat = ρ · g · h),

p_Last

= static pressure component of rated load.

Preferably, the static pressure of the loaded with nominal load car p_stat_Last by measuring the static pressure at unloaded, that is empty car p_stat_leer and calculating by: p_stat_Last = p_stat_leer + p_load (5) determined, where p_Last is the calculated static pressure component of the rated load.

The Procedure contains preferably at least the following steps: measuring the speed in uphill drive of the preferably empty or partially loaded car c; measure up the total pressure increase in the system when driving upwards the preferably empty or partially loaded car Δp_tot_auf; and measuring the static pressure at preferably empty or partially loaded Car at the preferred uppermost holding position p_stat_leer (p_stat_leer above).

The The invention thus provides for the technical examination the fallback correction the value for the total dynamic pressure p_dyn_Last of a nominal load loaded Car from (design-related) known and (currently) measured Sizes and preferably over to calculate the resistance coefficients. The inventors found that this approach, which in the prior art so has not yet been trodden, surprisingly to very accurate test results leads; Deviations between the calculated according to the invention and the actually present dynamic pressure of an actual loaded with nominal load car in upwards yielded for the reliable exam the sinking correction is negligible small. This can be done in the test procedure Advantageously, the loading of the car with full rated load be waived. The solution according to the invention thus makes it possible to completely check one generic elevator system within the meaning of the relevant Guidelines within normal operating travel and under normal Operating conditions without having separate measures for the exam such as obtaining from Payload weights must be taken.

Detailed description the invention

For hydraulic elevators, the following simplifying assumptions can be made: The basis is the physical consideration of the overall system, taking into account the energy conservation law. The basis is the energy equation according to Bernoulli. For the descent:

If the energy equation is reduced to the dynamic components, the result is:

The following sequence of movements takes place in the system Elevator: Upward travel: static end position down = start of the movement from rest position; static end position above = end of the movement in rest position:

Vice versa applies to the downward travel: static end position 1, above = start of the movement from rest position; static end position 2, bottom = end of movement in rest position:

The Density ρ of the Hydraulic system is considered constant. By use an incompressible fluid, this consideration is sufficiently accurate.

Dynamic pressures are proportional to the square of velocities (p _v ~ c _v ² ). The speed is minimized when moving from position 1 (below) to position 2 (above) to the losses due to friction. Conversely, the speed when traveling from location 2 (top) to location 1 (bottom) also minimizes friction losses.

It the static pressure p_stat_leer is measured, especially when the car is empty or partially loaded, which is in the area of, preferably positioned at the topmost stop (top car position), this means was stopped. The static pressure is preferably switched off Pump and preferably with means of one in the pressure side of the hydraulic system, For example, in the pressure line to the lifter, inserted calibrated Pressure measuring device, such as a manometer or electrical Sensors, read or registered over time or detected.

According to the invention, in a subsequent further step, the static pressure p_stat_Last of a car loaded with nominal load is calculated according to: p_stat_Last = p_stat_leer + p_load

The pressure p_load is the, preferably from the known construction and operating data of the hydraulic elevator, calculated static pressure component of the rated load. This is preferably calculated according to:

Where G = weight of nominal load [kg · m · s ^-2 ], i = suspension ratio, n = number of hydraulic cylinders and A = hydraulic piston area [mm ² ]. This pressure is usually calculated once and remains for this hydraulic lift for further testing for the future. Any partial load during the measurement must be taken into account when calculating the pressure component of the rated load. Ideally, however, the check is carried out when the car is empty.

p_Last If the car is unloaded, it represents the full static pressure component the nominal load. In a partially loaded car, for example by modifications or other measures or in the presence of a lift operator or test engineer p_Last represents the respective supplement to a nominal load loaded Car required static pressure component: drives during the test run a person with z. B. 75 kg body weight and a measuring device with 5 kg weight, so is in the calculation from p_load only the weight of around this partial load of 80 kg reduced nominal load.

The Measurement of the speed c_auf is preferably done by direct Measuring the speed of the moving elevator elements; alternatively by measuring the path as a function of time. The measurement takes place preferably on the car or on the outgoing / arriving Jack piston. It is preferably carried out by means of exciters, acceleration or speed sensors. The measurement of the speed can also at one or more points on the system at the same time or take place in succession.

The Measuring the speed can be done by directly measuring the speed or by measuring the distance as a function of time. The measurement of the speed refers to the speed the car and / or the extending / retracting cylinder and / or the flow rate of the fluid in the hydraulic system.

In In a preferred variant, a speedometer is stationary mounted on the car roof of the car or hung up, the the change the position of the car in the shaft during the test drive in dependence registered by the time. If necessary, the speedometer determines already internally the occurring maximum and average values the speed and display it. The speed measurement takes place preferably by means of continuous measurement of the relative movement of the car opposite fixed machine or shaft parts, such as shaft wall, rail system, Cable suspension, which preferably must have a flat surface, the preferably is stretched perpendicular to the direction of travel.

In another preferred variant, the flow rate of the fluid, preferably measured in the pressure side, of the hydraulic system, and preferably by inductive, capacitive or mechano-acoustic Flow sensors. The inventors found surprising that the determination of the flow velocity of hydraulic fluid in the system measuring the movement of the Elevator elements, especially the car, sufficiently accurate replaced. this makes possible a particularly simple determination of the elevator and car movement and thus a particularly simple implementation of the technical test, wherein in particular, do not enter the elevator shaft and / or the car must become. The invention accordingly also relates to a method for determination elevator / car movements and speeds, wherein the flow rate of the hydraulic fluid, preferably at the pressure side becomes. The measurement of the flow velocity takes place preferably on the pressure side of the pump in the flow direction seen after the shut-off valve, preferably by means of dynamic pressure principle or as ultrasonic flow measurement in a known manner.

at the test drive will preferably go through a full upward journey. Prefers are measured values recorded by electronic sensors (pressure, speed) recorded in a single data acquisition unit and on the Time recorded. Preferably, one or more trips are performed and the arithmetic mean of several measured values formed.

The Invention looks for the exact exam the drop correction the exact determination of the pressure loss coefficients in front. So that a detailed recording of the pressure loss coefficients at up- and optionally in addition, when driving down can be made in addition to the detailed measurement of kinetic energy components in the form of recording the velocity profile in upwards and downhill, the total pressure difference Δp_tot_oben and Δp_tot_unten be determined. This allows the entire system to be considered the dynamic energy shares and their losses completely described become.

For the upward travel from position 1 (below) to position 2 (above) applies to the energy expenditure of the pump: p_tot_auf = Δp_tot_oben = Δp_stat_oben + Δp_dyn_auf p_stat_oben = p_system + p_hydrostat + p_stat_load p_system_unten = p_system_up (Δp_system = p_system_oben - p_system_unten = 0); Δp_hydrostat = ρ · g · Δh Δp_stat_oben = ρ · g · Δh + Δp_stat_load Δp_dyn_auf = Δp_kin_auf + Δp_v_oben = Δp_tot_oben - p_stat_oben

For the downward travel from position 2 (top) to position 1 (bottom) applies to the released layer energy: Δp_tot_ab = Δp_tot_unten = Δp_stat_unten + Δp_dyn_ab Δp_stat_unten = Δp_system + Δp_hydrostat + Δp_stat_load Δp_stat_unten = ρ · g · Δh + Δp_stat_load Δp_dyn_ab = Δp_Kin_ab + Δp_v_unten = Δp_tot_unten - p_stat_unten

To determine the resistance coefficients of the overall system, the following dependencies are set according to the invention: drag coefficient of the upward travel Σζ_ab:

Drag coefficient of downward travel Σζ_ab:

The exact proof of the effectiveness of the Absinkverhinderungseinrichtung is assumed by the inequality Δp_tot = Δp_dyn + p_stat <p_DBV According to the invention therefore preferred: Δp_tot_up = Δp_dyn_up + p_stat_load <p_DBV

und p_dyn_Last = γ p_stat_Last The dynamic factor γ for calculating the dynamic pressure at full load is determined according to the invention according to:

and p_dyn_Last = γ p_stat_load

und Δp_tot_auf = p_stat + Δp_dyn_auf The inventors found: The efficiency of the anti-sink device is determined by the pump's pumping action at the operating point of the system curve. Thus, the determination of the dynamic pressure with respect to the average static pressure of the upward travel is used to assess the effectiveness of Absinkverheindernseinrichtung. The entire hydraulic system is thus uniquely determined by measuring the kinetic components and determining the static components as well as by determining the total pressure increase:

and Δp_tot_up = p_stat + Δp_dyn_up

p_stat is the mean of the static (resting) pressure, preferably read on the manometer with car in each lower and upper holding position, preferably with completely empty car (p_stat_leer):

bevorzugt:

Δp_tot_auf is the average value of the measurement of the total pressure gradient during the upward travel; c_auf is the mean of the speed during the uphill run.

prefers:

To prove the correct or sufficient effect of the fall-off correction according to the invention, the following must apply: p_dyn_load> γ p_stat_load

When determining p_dyn_voll, the dynamic factor from the upward travel γ is multiplied by the calculated static pressure (p_stat + p_stat_Last), where m is the mass of the maximum payload. Thus, the operation of a performance-dependent pump control is concretely modeled. For non-regulated pumps, the system characteristic curve and pump characteristic curve are changed at the operating point to sinking flow and decreasing delivery head. Thus, in total, the system experiences a reduction of the system parameters pressure, in order to keep the flow (speed) constant. In the examination of the effectiveness of Absinkverhindernseinrichtung accordingly has an additional advantage that the dynamic component shifts by a smaller proportion on the pump curve than by the calculated by the dynamic factor γ change in the dynamic pressure component. Thus, in the case of uncontrolled pumps, a reserve is contained in the procedure according to the invention: p_dyn_load <p_DBV; γ <k_DBV

The Invention also looks the correction or adjustment of the speeds (conveying speeds) in ascent and descent in front. This is done according to the invention by Determination of the resistance coefficients for the system upwards Σζ_on and the system descend Σζ_ab and the medium speeds of uphill c_auf and downward travel c_ab. These are preferably measured in the manner described above or determined. The overall system hydraulic elevator in his Plant parameters is set according to the invention so that the Resistance coefficients for upward and downhill up to 10%, maximum 15%. Through the settings on System (eg throttle from the outlet device), the delivery speeds can almost to be evened out.

According to the invention systemic losses based on average speed when driving down the total pressure increase while downhill determined and determines the density of the hydraulic oil.

Δp_tot_ab

= Mittelwert aus der (schreibenden) Druckaufnahme am Druckmesssensor während der Abwärtsfahrt;

p_stat_Last

= Wert aus Messung des statischen Druckes leer und des berechneten Druckes bei Nennlast.

Here are:

Δp_tot_ab

= Average value from the (writing) pressure absorption at the pressure measuring sensor during the descent;

p_stat_Last

= Value from measurement of the static pressure empty and the calculated pressure at rated load.

The method further provides for determining the setting values for the hydraulic lift by comparing Σζ_up with Σζ_ab and adjusting the parameters for upwards and downwards travel, preferably by adjusting the throttle valve, for downwards travel until the difference of the drag coefficients is less than 15%, especially less than 10% is: Σζ_on - Σζ_ab <10%

The Invention also sees in this context a new improved Procedure for testing the pressure limit. The sufficient function of the pressure relief should preferably before the above-described examination of Absinkverhinderung checked become. In this context, p_max in the system, ie p_DBV, can also be used. be determined.

For sufficient function of the pressure relief valve (DBV), the following inequality must be fulfilled:

there p_DBV is the measured response pressure (limiting pressure) of the pressure relief valve. This is measured in a conventional manner; preferably p_DBV when operating the hydraulic system with closed gate valve (hydraulic obstacle) or while driving the car against Obstacle (mechanical obstacle), preferably stop, measured. The response pressure is preferably when the pump and preferably by means of a calibrated inserted in the pressure side Pressure measuring device, for example a pressure gauge (with maximum value memory) or electrical sensor, read or recorded.

Preferred implementation of exam

aims The examination: a) proof of the correct setting of the pressure relief valve; b) Evidence of the effectiveness of the Absinkverhinderseinrichtung set correctly Pressure relief valve without the payload loaded car

1. test equipment

• - Calibratable pressure gauge, if necessary with pressure recording (writing pressure gauge); Measuring accuracy <± 1%
• - Speed measuring device

2nd test procedure: Pressure relief valve

The test requires a properly adjusted pressure relief valve. 2.1 Recording the technical parameters Load capacity (nominal load): Q [N] Piston diameter: d [mm] Suspension of the car: i Number of cylinders: n

2.2 Mounting a calibrated pressure gauge and determining the response pressure of the pressure relief valve p_DBV:

• - Gate valve shut down
• - Main switch "Off" (System depressurize)
• - Measuring device at the test connection of the control valve block
• - Open the gate valve
• - Mainswitch on"
• - call in the top stop
• - Gate valve shut down
• - Print Read off p_DBV

2.3 Measuring the static pressure at Unladen car:

• - car Position in topmost stop
• - Static Read pressure in unladen p_stat_leer state

2.4 Calculating the static pressure under rated load from:

2.5 Verification (test condition): p_DBV / p_stat_voll ≤ 1.4

3rd test procedure: Effectiveness of Absinkverhindernseinrichtung

The Effectiveness of Absinkverhindernseinrichtung is set properly Pressure relief valve and empty car (not loaded with payload) checked

3.1 Installation of measuring equipment for the parameters Speed and pressure

• - Assembly the measuring device in or on the system Elevator for measuring the car speed in uphill drive (c_auf) and if necessary downhill (C_ab)
• - Assembly Pressure measuring sensor (writing pressure measuring sensor) on the test measuring socket the plant.

3.2 Measuring the static pressure at empty (unladen) car:

• - car position in topmost stop; static pressure in the unloaded Read state p_stat_leer; the top halftone is the one Position at which a reliable Absinkkorrektur is still to take place, regularly the stop at the top Floor.

3.3 Density ρ of the hydraulic fluid determine:

• - Drain of the hydraulic oil and determine the density (eg with measuring spindle)

3.4 Carry out test drive:

• - Driving cycle (only upwards) To run
• - Take up the measured values of the speed in the system (c = f (t)) in upward travel (c_auf) and averaging at a medium speed c_auf
• - Take up the total pressure increase while the uphill drive by pressure measuring sensor and averaging of the mean total pressure increase Δp_tot_auf for the upward movement

3.5 evaluation:

• – Druckverlustbeiwert ermitteln aus:
  
  p_stat_voll = p_stat_leer + p_last;p_Last = berechneter Druck bei Nennlast
• – Koeffizient γ ermitteln aus: Δp_dyn_auf_leer = ρ·(c_auf²/2) + Σζ_auf ρ·(c_auf²/2)
  
• – Berechnen von p-dyn_Last: p_dyn_Last = p_stat_Last·γ
• – Berechnen von k_DBV: k_DBV = p_DBV/p_stat_Last

The system-related losses are determined on the basis of the measured average speed during upward travel c_auf, the total pressure increase during the upward travel Δp_tot_auf and the measured density ρ of the hydraulic fluid.

• - Determine pressure loss coefficient from:
  
  p_stat_voll = p_stat_leer + p_last; p_load = calculated pressure at rated load
• - coefficient γ determined from: Δp_dyn_auf_leer = ρ · (c_auf ^2/2) + Σζ_auf ρ · (c_auf ^2/2)
  
• Calculate p-dyn_Last: p_dyn_Last = p_stat_Last · γ
• - Calculation of k_DBV: k_DBV = p_DBV / p_stat_load

4. proof

• criterion: p_dyn_load <p_DBV; γ <k_DBV

Of the Calculated dynamic pressure with the car loaded with rated load p_dyn_Last must always be lower than the measured set pressure p_DBV of the pressure limiter (= maximum sustained pressure in the system):

Example: Concrete execution of the exam

• 1 exam the pressure relief valve
• 1.1 Inclusion of technical parameters: Nominal load Q: 630 kg Weight (G = Q · g): 12360,6 N Piston diam. d: 100 mm piston area A: 0.00785 m ² Suspension i: 2-fold Number of cylinders n: 1
• 1.2 Measurement of the response pressure (= maximum pressure in the system): p_max = p_DBV = 58.60 bar
• 1.3 Calculating the mean static pressure with unloaded car from the measurement of the static pressures at the lowest and the uppermost stop: p_stat_leer_unten = 26,30 bar, p_stat_leer_oben = 27,55 bar; p_stat_leer = (p_stat_leer_unten - p_stat_leer top) / 2 = (26,30 bar + 27,55 bar) / 2 = 26,93 bar
• 1.4 Calculating p_stat_Last with: p_load = 15.75 bar (calculated) p_stat_Last = 26.93 bar + 15.74 bar = 42.67 bar Measurement of mean static pressure with empty car at topmost stop: p_stat_leer top = 27.55 bar
• 1.5 Verification of the test criterion:
  
  p_DBV / p_stat_Last = 58.60 bar / 42.67 bar = 1.39 <1.4 -> Test passed
• 2. Exact examination the Absinkverhindernseinrichtung
• 2.1 Density of the hydraulic fluid (system-specific): ρ = 0.85 g cm ^-1
• 2.2 lifting height (lift-specific)): Δh = 15 m
• 2.3 Test run - upwards: average values of the test runs: c_auf = 0.611 ms ^-1 p_tot_auf = 31.86 bar
• 2.4 Calculating Dynamic Factor · γ:
• 2.4.1 drag coefficient.
  
• 2.4.2 Dynamic pressure component during upward travel.
  
• 2.4.3 Dynamic factor:
  
• 2.5 Calculating the total dynamic pressure at rated load: p_dyn_load = p_stat_full · γ = 42.66 bar - 1.16 = 49.49 bar
• 2.6 examination: p_max = p_DBV = 58.60 bar (from 1.); p_dyn_Last = 49.49 bar p_dyn_Last <p_DBV -> Test criterion fulfilled

Claims (10)

Method for the technical testing of hydraulic lifts, comprising the steps of: - determining the maximum pressure p_max in the system - determining the static pressure for a nominal load loaded car p_stat_Last in the system - determining the dynamic pressure for a nominal load loaded car p_dyn_Last after: p_dyn_Last = γ · p_stat_load where γ is the dynamic factor and for sufficient function of Absinkverhinderung the test criterion p_dyn_Last <p_max must be fulfilled. The method of claim 1, wherein the dynamic factor γ is calculated according to:

with: p_tot_auf = dynamic total pressure when driving upwards, p_stat = static pressure in the system when the car is in the upper stop position The method of claim 2, wherein:

with: c_auf = average speed of the car in upward travel, ρ = density of the hydraulic fluid, Σζ_auf = sum of the drag coefficients during upward travel The method of claim 3, wherein:

with: p_tot_auf = average total pressure during upward travel, p_hydrostat = hydrostatic pressure component of the hydraulic fluid, p_load = static pressure component of rated load, Method according to one of the preceding claims, wherein the one in determining the pressures and the speed of the car is unloaded (empty). Method according to one of the preceding claims, wherein the static pressure of the loaded with nominal load car p_stat_Last by measuring the static pressure with empty car p_stat in and calculating to: p_stat_Last = p_stat + p_load, is determined, where p_Last is the calculated static pressure component of the rated load. Method according to one of the preceding claims, comprising the steps: - Measure up the speed of the upward drive of the empty car c_auf - measuring the mean total pressure increase in System in the upward drive of the car p_tot_auf - Measure up the static pressure at car at the upper stop position p_stat Method according to one of the preceding claims, wherein p_max the set pressure of the tested pressure relief valve p_DBV corresponds. The method of claim 8, wherein for checking the sufficient function of the pressure relief valve, the inequality

must be met, where p_DBV is the measured response pressure of the pressure relief valve. Method according to one of the preceding claims, wherein Speed c_auf, as the flow velocity of the hydraulic fluid is measured in the system when driving the car.