WO1993015323A1 - High-pressure hydraulic unit - Google Patents

Abstract

High pressure hydraulic unit, more particularly a hydropneumatic pressure multiplier device, comprising a working chamber (3) exposed to variable pressures controlling a working piston (2) acting, by means of a piston rod (4), towards the outside of the group, the high pressure can be generated in particular by an additional piston (15). The pressure of this working chamber (3) can be measured by means of a pressure measuring element which makes it sealed with respect to the outside. In particular, a piezoelectric device or an indicator mounted on a spring can serve as a pressure measurement element.

Description

Hydraulic high pressure unit

The invention is based on a hydraulic high-pressure unit according to the type of the main claim.

In the case of high-pressure units of the generic type (see brochure from Pressotechnik GmbH, edition 0201.9103), the working space, which is alternately acted upon between high pressure and low pressure, is provided with a high-pressure measuring and control connection. This can be used to initiate film functions, such as setting the press force independently of the line pressure with return stroke triggering, line pressure monitoring and thus production control, switching on subsequent functions such as welding current connection with guaranteed press force, connection to a manometer, etc. The working pressure in the work area is therefore measured hydraulically, for which an oil pressure measuring line is required, which then leads to a manometer or a Pressure sensor leads. The pressure transmitter designed as a pressure switch gives a corresponding signal at a predetermined and set pressure, which signal is processed in a control or regulating device.

This measuring and control connection used in the generic hydraulic high-pressure units has the disadvantage that the connection point to the work area is exposed for its assembly or repair, so that air can get into the work area but also into the high-pressure measurement line. which disadvantages the measurement, but also the function, of the hydraulic unit. Leakages in the measuring system as well as careless operation of the unit with the measuring system can lead to the escape of hydraulic oil with the corresponding disadvantages. For this reason, the maintenance effort for such units is very high.

The hydraulic high-pressure unit according to the invention with the characterizing features of the main claim has the advantage that even when carelessly operated during the pressure measurement, hydraulic oil can no longer escape, nor can air penetrate into the working space of the unit. The unit is therefore always fully operational. In addition, the pressure element can serve as a transmitter for a wide variety of measuring devices, depending on the design of the pressure element. Such a pressure element can also be used Strain gauges. However, a connecting part (nipple or the like) can also serve as the pressure element, which has only coupling or transmission tasks to a measuring device.

It is particularly advantageous to use the invention in a hydraulic high-pressure unit which works as a hydropneumatic pressure intensifier with the features of claim 2. With such hydropneu- matic pressure intensifiers (see also DE-OS 38 28 699) it is very important that neither Air gets into the work area, oil still leaks out, because with the very high number of switching operations, such devices must have no functional weakness - for example in the manufacture of motor vehicles - a lack of function would have devastating consequences.

According to a further advantageous embodiment of the invention, the pressure element has a sensor pin which is radially sealing and axially displaceable against a restoring force in a unit housing bore, which is acted upon by hydraulic pressure on its end face and which serves as a stroke transmitter. Such an encoder pin has considerable advantages in the direct transmission of pressure, since the hydraulic oil acts directly on its end face.

In order to obtain a direct measure of the existing pressure via the stroke of the encoder pin, a further embodiment of the invention requires that the encoder pin be on Bund present, which serves on the one hand as a stroke stop and on the other hand as an abutment of a spring as a restoring force whose characteristic corresponds to the pressure / stroke value.

According to a further advantageous embodiment of the invention, a switch, position measuring system or an optical system can be actuated by the stroke transmitter, in which a switch is actuated at a preset pressure and corresponding stroke of the stroke transmitter, after which the switching pulse can be processed electrically or pneumatically or by measuring the path of the encoder pin, from which the pressure can be calculated analog or digital, or by optically controlling the stroke of the encoder pin either directly or by a device. or by the sensor pin acting on a piezo pressure sensor or another pressure sensor, which can be mounted relatively easily on the housing of the high-pressure unit.

According to a further advantageous embodiment of the invention, a check valve which closes towards the pressure element is arranged in the unit housing between the pressure element and the working space and is opened by the transmitter pin when the pressure element is installed, so that the pressure element can be replaced in the working space without pressure reduction or can be replaced by a stopper, because the check valve closes immediately and separates the work area from the environment. Of course, this also makes it possible to use the pressure element as a nipple for a high-pressure oil hose, since it is only fixed screwed-in nipple, the check valve is pushed open by the transmitter pin, but when the nipple is unscrewed, the check valve immediately closes.

According to another advantageous embodiment of the invention, a piezo element that can be installed directly in the unit housing serves as the pressure element, the signals being electrically processable in a corresponding device. The measurement using such a piezo element is very precise and has a high resolution. In addition to the pressure measurement, the entire pressure build-up can also be measured and made visible.

Further advantages and advantageous embodiments of the invention can be found in the following description, the drawing and the claims.

An embodiment of the object of the invention is shown with three variants in the drawing and described in more detail below. Show it:

1 shows a hydropneumatic pressure intensifier in longitudinal section.

2 shows a first variant of the sensor from FIG. 1 in conjunction with a check valve; Fig. 3 shows a second variant with a stroke encoder and

4 shows a third variant for a high-pressure hose connection, the variants compared to FIG. 1 being shown on an enlarged scale.

In the hydropneumatic pressure intensifier shown in FIG. 1, a working piston 2 is arranged axially displaceably and radially sealingly in a housing 1 and limits with it a working space 3 filled with hydraulic oil. On the working piston 2 there is a protruding outside the housing Piston rod 4 is arranged. In addition, the working piston 2 as a collar has an auxiliary piston 5, which is radially sealed off from a casing tube 6 and thereby separates two pneumatic spaces 7 and 8, which are alternately supplied with pneumatic pressure for the rapid traverse of the working piston 2. As soon as there is sufficient working pressure in the pneumatic space 7, the working piston 2 is pushed down and vice versa, with a correspondingly high pressure in the pneumatic space 8 and a reduced pressure in the pneumatic space 7, the working piston 2 is pushed back into the starting position shown.

14 durch Druckluft beaufschlagt wird, aucht nach Zurücklegung eines bestimmten Hubes der :auchkolben 15 in eine vom Speicherraum 9 zum Arbeits¬ aum 3 führende Verbindungsbohrung 17, wonach diese erbindung unter Mitwirkung einer Radialdichtung 18 terbrochen wird. Bei weiterem Hub des Tauchkolbens 15 d entsprechend tieferem Eintauchen in den Arbeits- •.ium 3 wird dort dadurch Hydraulikflüssigkeit verdrängt, _■-> daß ein hoher Arbeitsdruck im Arbeitsraum 3 entstehen V-inn. Dieser Druck entspricht dem Übersetzungsverhältnis ^r Arbeitsflächen von Antriebskolben 14 zu Tauch¬ kolben 15 ausgehend von dem den Antriebskolben 14 be- _?.χischlagenden pneumatischen Druck. Der dabei --stehende hohe hydraulische Druck wirkt unmittelbar _£;.:^" den Arbeitskolben 2 und bewirkt die gewünschte hohe j: -uit an der Kolbenstange 4. Für den Rückhub wird der

Druck im Antriebsraum 16 abgebaut, so daß .-.le Speicherfeder 12 den Antriebskolben 14 in die . zeigte Ausgangslage zurückschiebt, wonach aus dem '.rbeitsraum 3 durch den Arbeitskolben 2 verdrängt, ^•r.v'draulikflüssigkeit in den Speicherraum 9 strömt und ..obei der Arbeitskolben 2 durch Druckluft im Raum 8, die R Hilfskolben 5 angreift, in die gezeigte Ausgangsläge --=rschoben wird.Above the working space 3 and hydraulically connected to it is a storage space 9 for hydraulic oil, the storage pressure of which is generated by a storage piston 11 and a storage spring 12. The storage piston 11 is guided in a radially sealing, axially displaceable manner in a jacket tube 13. Also radially and axially displaceable, a drive piston 14 of a plunger 15 is mounted in this jacket tube 13 and can be displaced in the direction of the working space 3 against the force of the storage spring 12. The plunger 15 penetrates the storage piston 11 in a radially sealed manner and plunges into the storage space 9. The drive piston 14 with plunger 15 is driven by compressed air which is directed into a drive space 16 above the drive piston 14 when the working piston 2 has ended its rapid traverse, the rteißt that on the piston rod 4 mounted tool has been brought into ^• -.rbeitslage. Once the

14 is acted upon by compressed air, even after covering a certain stroke of the: also piston 15 in a connecting bore 17 leading from the storage space 9 to the working space 3, after which this connection is broken with the participation of a radial seal 18. With a further stroke of the plunger 15 d, correspondingly deeper immersion in the working • .ium 3, hydraulic fluid is displaced there, _ ■ -> that a high working pressure is created in the working space 3 V-inn. This pressure corresponds to the transmission ratio of working surfaces from drive piston 14 to plunger piston 15 starting from the drive piston 14 _? . pneumatic pressure. The case --stehende high hydraulic pressure acts directly _£;:. ^"The working piston 2 and provides the desired high j: -uit 4 on the piston rod for the return stroke is the

Pressure in the drive chamber 16 reduced, so that .-. Le storage spring 12, the drive piston 14 in the. showed starting position pushes back, after which displaced from the '. Working space 3 through the working piston 2, ^• r. hydraulic fluid flows into the storage space 9 and Starting position - = pushed.

v.-m. Working space 3 branches off to the outside in the housing 1, into which a p. 'Emitter 21 is screwed, which works with piezoelectric p ..; "-: means and via electrical lines 22 with _p; The piezoelectric pressure sensor detects actual pressure profiles in the work space 3, since it (jwr the bore 19 is acted upon directly by hydraulics under a pressure space pressure.

χ _r Figure 2 is a variant of the pressure transducer darge s _t ellt, wherein on its side facing the working space 3 c ^ - e, a pin 23 is arranged, which on a ball 24 it _eι- check valve acts, which by a ^* F _* ^he 25 loaded, with the pressure transmitter 21 unscrewed the B _C ιrung 19 blocks. The pressure sensor 21 is by a R _a . aldichtung sealed to the housing. In this _W e the hole 19 is always locked, will be expanded when the D .c encoder 21, ektionszwecke example for I- ^, repairs or when an _ar .. rer thruster to be used instead of him. In the variant according to FIG. 3, a non-return valve as in FIG. 2 is also used, except that a transmitter pin 27 is used as the pressure element, which is screwed into the housing 1 via a bushing 28 and thereby acts on the ball 24. The encoder pin has a collar 29 which is loaded by a measuring spring 31. As soon as there is sufficient pressure in the work area 3, the encoder pin. 27 pushed against the measuring spring 31 more or less in accordance with the prevailing hydraulic pressure, this travel path being used as a measured variable. The switch pin can either be used to actuate a switch after a certain stroke has been completed, or this path can be measured and converted into control variables, such as switching off the working stroke of the plunger 15, etc. Advantageously, the diameter of the bushing 28 is equal to that of the pressure sensor 21 in FIG 2, so that these two sensors can alternatively be used in a hydropneumatic pressure intensifier.

In the third variant shown in Figure 4, a nipple 32 is screwed into the bore 19, which has a central bore 33 and a hose connection 34. Via such a hose connection, a connection to a hydraulic pressure measuring device can be made, which is interrupted at the moment when the Nipple 32 is screwed out of the bore 19 again and the ball 24 locks the bore 19 again. All features shown in the description, the following claims and the drawing can be essential to the invention both individually and in any combination with one another.

LIST OF REFERENCE NUMBERS

1 housing 29 collar

2 working pistons 30 -

3 Working area 31 measuring spring

4 piston rods 32 nipples

5 auxiliary pistons 33 centr. drilling

6 jacket tube 34 hose connection

7 pneumatic room

8 pneumatic room

9 storage space

10 -

11 accumulator pistons

12 spring

13 jacket tube

14 drive pistons

15 plungers

16 drive compartment

17 connecting hole

18 radial seal

19 hole

20 -

21 pressure sensors

22 electrical cables

23 pin

24 bullet

25 spring

26 radial seal

27 encoder pin

28 socket

Claims

Claims 1. Hydraulic high pressure unit with a hydraulic working space for changing pressures, namely a low accumulator pressure (supply pressure) and a high working pressure (high pressure), which is arranged in an aggregate area. with a working piston which delimits the working space and can be actuated by the working pressure in the unit housing for its working stroke and which leads through a piston rod to the outside, with a pressure generator which generates the changing pressures in the work space, in particular with a reciprocating piston, and - With a measuring and control connection for working pressure measurement in the unit housing, characterized in that the measuring and control connection as the working space (3) to the outside hydraulically sealing pressure element (21, 24, 28, 32) is formed, which is acted on the one hand by the hydraulic pressure of the working space (3) and on the other hand can be used as a means of pressure measurement. 2. Hydraulic high-pressure unit according to claim 1 of a hydropneumatic pressure booster marked by the following features a storage space (9) which can be hydraulically connected to the working space (3) and from which hydraulic oil flows under high pressure from the storage space (9) into the working space (3) during a rapid traverse of the working stroke and flows back again on the return stroke, - A plunger (15) which can be pneumatically actuated as a high-pressure generator against a restoring force (12) and plunges into the working space (3) after the rapid traverse of the working piston (2), a transverse wall between the working space (2) and the storage space (9), which has a central control bore (17) through which the plunger (15) penetrates in a radially sealing manner, - A pneumatically or mechanically loaded, axially displaceable and radially sealing storage piston (11) generating the storage pressure, which separates the oil-filled storage space (9) from an air-filled spring space containing the storage spring (12), air spring or helical spring, and - an auxiliary piston (5) on the working piston (2) (Collar) which can be alternately pneumatically pressurized for rapid traverse. 3. Hydraulic high-pressure unit according to claim 1 or 2, characterized in that the pressure element (21) in a unit housing bore (19) radially sealing and axially against a restoring force (31) displaceable encoder pin (27) ^* , which on the one hand on his Hydraulic pressure of the working area (3) is applied to the end face and on the other hand serves as a stroke transmitter. 4. Hydraulic high-pressure unit according to claim 3, characterized in that the encoder pin (27) has a collar (29) which serves as a stroke stop and as an abutment for a measuring spring (31) serving as a restoring force. 5. Hydraulic high-pressure unit according to claim 3 or 4, characterized in that a pressure transducer, in particular piezoelectric pressure transducer, switch, displacement measuring system or optical system can be actuated by the Hub¬ encoder (21). 6. Hydraulic high-pressure unit according to one of the preceding claims, characterized in that between the pressure element (21, 28, 32) and the working space (3) in the unit housing (1) closes towards the pressure element Check valve (24, 25) is arranged, which is pushed open by the encoder pin (23, 27) when installing the pressure element (21, 28, 32), so that the pressure element (21, 28, 32) without pressure reduction in the work space (3) is expandable. 7. Hydraulic high-pressure unit according to claim 1 or 2, characterized in that a piezo element (21) is used as the pressure element.