JPS61262202A - Pressure generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a pressure generator comprising a pump driven by an electric motor, a pressure accumulator, a pressure gauge connected to the pressure accumulator, and a control circuit. , this control circuit evaluates the signal of the pressure signal generator and connects the motor if it falls below a pressure limit value and switches it off depending on the pressure accumulator pressure, and also assigns an overpressure valve to the pressure accumulator. Regarding the format of

Conventional technology The charging of a pressure accumulator is conventionally turned on and off depending on the pressure of the pressure accumulator (by means of its connection and cutoff waves).

The pressure supply is also made safe via an overpressure valve, which serves to prevent overloading of the components in the event of a failure of the shutoff mechanism of the accumulator charge.

FIG. 1a shows a typical known pressure accumulator characteristic curve, in which the pressure p is shown as a function of the fluid volume V. Furthermore, each connection and disconnection operation (P
e and Pa) are shown together with their tolerances. The tolerance band of the overpressure valve C continues at a safe distance from the shutoff operation Pa. In the case of high-pressure devices, the design of each structural part of such a device creates significant expense and weight requirements, which increase approximately in proportion to the set pressure of the device. Due to its tolerances, it is also necessary in this case also to set pressure-dependent limit values for the overpressure valve, which leads to a significant increase in the cost of the device.

OBJECT OF THE INVENTION The object of the invention is to eliminate the disadvantages of the known devices mentioned above.

SUMMARY OF THE INVENTION According to the invention, the above-mentioned problem is achieved in that the motor is shut off essentially by the response of an overpressure valve.

Advantages and operation of the invention In accordance with the invention, the pump is switched off by electrical means at the permissible limit of the overpressure valve, so that the pressure load on the various components is significantly reduced, for example in the In the skid system, a reduction of about 35 nores, equivalent to 20 inches, is made.

This is possible in that the conventional switching off of the pump by means of a second switching limit setting with an associated tolerance band does not take place.

In the present invention, charging of the accumulator is carried out, as before, by switching the connection of the motor after the connection limit value has been reached.

The process of charging the pressure accumulator is then carried out until the overpressure valve responds. The point at which the pump is switched off can then be detected, for example, by differential calculation of the pressure history.

The response of the overpressure valve is indicated by whether its differential quotient becomes zero or extremely small within the temporal pressure history. According to a further embodiment, switching off the pump takes place via a timing element, which, depending on the pump output and the charge characteristic curve, determines that within the switching time the pressure in the accumulator is at least close to the response point of the overpressure valve. It is designed to be brought up to.

Embodiment FIG. 1b is a graph corresponding to FIG. 18 showing the shutoff operation in the present invention. In this case, no further charging of the pressure accumulator occurs due to the response of the overpressure valve.

The pressure difference Δp shown in comparison with FIG. 1a indicates the amount of possible pressure reduction, which has a significant influence on the dimensioning of the component.

FIG. 2 shows a first embodiment of the invention. On the right side of the figure, an electric pump 1 with a motor 2, a control relay 3, a pressure accumulator, an overpressure valve Ia and a pressure signal generator 5 are shown. This pressure signal generator 5 emits an analog signal via its electrical component 5a, which signal is fed to a converter 6 which defines the connection limit values for the motor. When the connection limit is reached, the bistable element 7 is set. The pump relay 3 is then controlled via the amplifier 8.

The starting signal of the pressure transmitter 515a is differentiated in a differentiator 9 and fed to a condenser 1o, which condenser A converter 1o is activated when a smaller limit value, for example zero, is reached (by actuation of the overpressure valve 4a). A signal is sent to the 771 circuit 11 whose starting signal causes the bistable element 7 to be reset. This charging process is simultaneously evaluated via a timing element 12, the time reference of which is optionally controlled as a function of temperature and voltage (control element 13). If the charging process continues for too long, the warning lamp 14 is turned on.

FIG. 3 shows a circuit with one timing element. After reaching the connection limit (contact 20), the bistable element 2 also controls the control relay 3 via the final stage 22.
1 is set.

The starting signal of this bistable member 21 is simultaneously applied to the timing element 2.
3, the starting signal of this timing element 23 resets the corresponding bistable element 21 after the time reference has been exceeded.

This switching action is not taken into account if the pump output is reduced. Further, in the additional switching mechanism 24,
The amount of fluid removed from the accumulator is evaluated and compared with the charging time.

This circuit, for example when used in a braking force amplifier, evaluates the maximum braking force p and the number of braking elements and compares it with the connection time of the pump, thus generating a connection signal A and a disconnection signal. B is supplied. If the reference value is exceeded in this case, a warning lamp 26 is activated via the amplifier 25.
control is performed.

In the example of FIG. 4, the connection control of the pump relay 3 is again switched to the second
Electrical components 5 of the pressure signal generator as in the example of the figure
a and the converter 6, and the switching off of this bistable element 30 is effected by means of a timing element 31 as shown in FIG. It is done through. The discharge output is checked by evaluating the rate of pressure rise (differentiator 32 and compensator 33). In this case, if a certain predetermined value is dropped during the charging process, the warning lamp 360 is turned on. In this case, the output signal of the converter ξlator 33 is 771 circuit 3
4, and the second inlet of this 771 circuit is connected to the outlet of the bistable member 3o.

[Brief explanation of the drawing]

FIG. 1a is a diagram for a pressure generator according to the prior art, FIG. 1b is a diagram for a pressure generator according to the invention, FIG. 2 is a circuit diagram showing a first embodiment according to the invention, FIGS. FIG. 4 is a circuit diagram showing various modified embodiments according to the present invention.

Claims (1)

[Claims] 1. A pressure generator consisting of a pump driven by an electric motor, a pressure accumulator, a pressure gauge connected to the pressure accumulator, and a control circuit, which controls the pressure Types in which the motor is connected if the signal of the signal generator is evaluated and falls below a pressure limit value and is switched off depending on the pressure accumulator pressure, and in which an overpressure valve is assigned to the pressure accumulator, Motor (2) is almost shut off by overpressure valve (4).
A pressure generator characterized in that the pressure generator is operated by the response of a). 2. Pressure generator according to claim 1, wherein the changes occurring in the pressure build-up gradient curve upon reaction of the overpressure valve (4a) are used for said shutoff. 3. According to claim 2, a pressure gauge is used that forms an electrical signal depending on the height of the pressure, the signal is differentiated, and this differentiated signal is compared with a smaller comparison value. pressure generator. 4. Pressure generator according to claim 1, wherein the switching off of the motor (2) takes place after a certain suitable measured time has elapsed since its connection. 5. The pressure generator according to claim 4, wherein the time period is formed depending on the amount of fluid taken out. 6. The connection time of the motor (2) is monitored and certain predetermined
Pressure generator according to one of claims 1 to 3, in which a warning is issued when a predetermined time is exceeded, depending on the temperature and/or motor voltage as the case may be. . 7. Pressure generator according to claim 4 or 5, in which the pressure rise slope curve during motor operation is monitored and a warning is issued if this pressure falls below a limit value. 8. The amount of fluid withdrawn from the pressure accumulator is compared with the connection time of the motor, and a warning is issued if the connection time becomes too long for a predetermined amount of fluid withdrawal. The pressure generator according to any one of item 1 and item 7.