GB2042631A

GB2042631A - Anti-frosting Pump

Info

Publication number: GB2042631A
Application number: GB8001809A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1979-01-19
Filing date: 1980-01-18
Publication date: 1980-09-24
Also published as: IT8019302A0; FR2446933B1; GB2042631B; DE2902028A1; IT1129568B; FR2446933A1

Abstract

An anti-frosting pump which can be fitted optionally upstream or downstream of the pressure regulator of a compressed air system has a valve 30 which can be set to connect the actuating chamber 22 either to the main air line via a passage 34 or to a separate control line via connection 32. <IMAGE>

Description

SPECIFICATION Anti-frosting Pump This invention concerns an anti-frosting pump for use in a compressed air system.

The invention is based on an anti-frosting pump having a pump cylinder, a pump piston and a working piston which is connected to the pump piston, which piston is subjected during its working stroke to the changing pressure in a pressure regulator which acts against the force of a return spring. An anti-frosting pump of this kind is known from German published patent specification Offenlegungsschrift 26 08 816.

Anti-frosting pumps of this kind involve the problem that they are subject to various installation conditions. in a first case, the antifrosting pump is to be disposed downstream of the pressure regulator and operated by the changing pressure in a special control line. In a second case, the anti-frosting pump is to be disppsed upstream of the pressure regulator. A special control line is then not required, and the connection piece for the control line then has to be closed. The changing pressure required is then taken from the main line.

Hitherto, different types have been supplied for the two constructions. Manufacture and stockkeeping were rendered difficult.

According to the present invention there is provided an anti-frosting pump for automatically introducing an anti-freezing agent into a compressed air passage having a pressure regulator therein, the anti-frosting pump comprising a pump housing, an air pressureoperated pump piston remoyable in a pump cylinder in the housing against the force of a spring for displacing the anti-freezing agent into the air passage, and a pilot valve which is selectively operable to apply a fluctuating pressure to the pump piston either from an auxiliary post or from a branch passage leading from said air passage, the auxiliary port being separately connectible to the pressure regulator if the anti-frosting pump is downstream thereof or being blanked off if the pump is upstream of the pressure regulator.

The anti-frosting pump according to the invention has the advantage that a single type of anti-frosting pump can be used for the two types of installation. The anti-frosting pump can-be adjusted accordingly before it is supplied to the customer, or even by the customer ..himself. The pilot valve is changed over externally through an actuation opening in the housing and is either adjusted to admit the pressure in the main line to a pressure-change chamber, or the control line is connected to the same opening in the housing, the pressure in which control line can then be admitted to the pressure-change chamber by way of the pilot valve.

In this manner, an anti-frosting pump can be changed over in a convenient, simple and inexpensive manner.

The present invention will be described further by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a section through the defrosting pump with the pilot valve installed, Fig. 2 shows the pilot valve, drawn to a larger scale, in a first switching position, Fig. 3 shows the pilot valve in a second switching position, Fig. 4 shows an example in which the defrosting pump is fitted for the position of the pilot valve of Figure 2, Fig. 5 shows an example in which the defrosting pump is fitted for the position of the pilot valve shown in Figure 3, and Figures 6 to 10 show varians of the pilot valve.

An anti-frosting pump for introducing an antifreezing agent into a compressed air system has a housing 1 in which a pump 2 is disposed.

The pump 2 has a pump cylinder 3 at the end of which is arranged a pressure valve 4/5. A seat 4 of the pressure valve 4/5 is formed by an annular extension in the housing 1, and a closure member 5 of the pressure valve 4/5 is in the form of a plate. The plate is disposed laterally in a through passage 6 of a compressed air system (not further illustrated) where it is acted upon by a spring 7 which seeks to hold the closure member 5 of the valve on its seat 4.

The spring 7 is housed in a spring chamber formed in the housing 1. An annular sealing ring and an abutment plate for the spring 7 form one end of the spring chamber and are retained by a circlip which is located in a groove in the wall of the chamber.

That end 8 of the pump cylinder 3 which is adjacent to the valve seat 4 is provided with a step 9/10. The step has in the valve sea 4 a portion 9 of reduced diameter which continues in the form of a conical member 10 and then merges into a cylindrical portion 11 of the pump cylinder 3.

An annular recess 12 is provided at the top end of the pump cylinder 3 and accommodates an 0ring seal 13. The ring seal 1 3 is intended for cooperation with a cylindrcal outer wall 14 of a pump piston 1 5 whose end 1 6 facing the pressure valve 4/5 has a reduced portion whose shape is adapted to conform substantially to the configuration of the pump cylinder 3.

The pump piston 1 5 is connected to a working piston 20 which is subjected to the force of a spring 21 in the direction of the suction stroke and, in the direction of the delivery stroke, to the changing pressure of a pressure regulator connected to a pressure-change chamber 22.

The pump piston 15 also has a seal in the form of an O-ring seal 23 which sealingly engages with the bore in which the pump piston is movable.

The spring 21 is accommodated in a suction chamber 24 which is fed with antifreeze agent by way of a port 25. The antifreeze agent fills the pump cylinder 3 up to the level of the port 25 in the suction chamber. The closed pressure valve 4/5 prevents the antifreeze agent from entering the through passage 6.

However, when a pressure surge comes from the pressure regulator, this pressure surge also acts in the pressure-change chamber 22. The working piston 20 moves downwardly against the force of the spring 21, and the pump piston 1 5 secured to the working piston 20 enters the annular seal 13 in a plunger-like manner. The flow of antifreeze agent into the pump cylinder 3 is thus interrupted.

Upon a further pressure rise in the pressurechange chamber 22, the pump piston 1 5 displaces the antifreeze agent from the pump cylinder 3 into the through passage 6 by way of the opening pressure valve 4/5. The end 1 6 of the pump piston is so shaped that at the end of the pressure stroke, the pump piston 1 5 virtually completely fills the pump cylinder 3.

A pilot valve 30 is illustrated at the top left of Figure 1 and is disposed in a multi-stepped housing bore 31 which leads to the presssurechange chamber 22. The housing bore commences at a connection piece 32 which can be closed either by a screw plug 33 (Figure 3) or by a hollow connection screw 40 (Figure 2). A junction or branch passage 34 opens radially into the housing bore 31 and communicates with the through passage 6 of the main line.

The bore 31 containing the pilot valve 30 has a first port communicating by way of a passage 34 with the main air line 46 and a second port communicating with the pressure change chamber 22.

The pilot valve comprises an outer cylindrical member which surrounds a valve piston 37. A pair of seals 35, illustrated as 0ring, sealingly engage the outer surface of the valve piston. An aperture located in the cylindrical member between the two seals establishes communicaton between the interior and exterior of the cylindrical member.

The valve piston 37 has a cross drilling or passage which communicates with a centrally disposed bore. The valve piston is slidably disposed within the cylindrical member and in a first position communication between the first port and the second port is interrupted. This corresponds to the position illustrated in fig. 2. A spring 39 contained partially within the central bore of the valve piston and abutting against a shoulder of the bore 31 in the housing normally biases the valve piston into this position.

In a second position, where the valve piston is displaced against the force of the spring 39 communication is established between the first and second ports.

The valve piston 37 is actuated by a plunger 38 connected in series therewith.

Figure 2 shows the valve piston 37 in a position which it can assume when a hollow connection screw 40 is provided in the connection piece 32 instead of the screw plug 33.

In this position the second port is in communication with the connection piece 32 by way of the crossdrilling in the valve piston 27. A control line 41 is then connected to the connection piece, and changing pressure is introduced to the pressure-change chamber 22 from the control line 41 and acts upon the pump piston 20 and actuates the pump 2. The branch passage 34 is shut off by the pilot valve 30.

Figure 3 shows a type of installation in which the control line 41 is not provided. Upon the screwing-in of the screw plug 33, the inner end face of the latter presses the valve piston 37 to the right against the force of the spring 39 to an extent that the valve piston opens the branch passage 34. The changing pressure in the main air line is then introduced into the pressure- change chamber 22 from the through passage 6 and actuates the pump 2.

Corresponding systems are shown in Figures 4 and 5. A compressor 45 feeds air into a main air line 46 in which are fitted a pressure regulator 47 and an anti-frosting pump 48. An antifreezing agent reservoir is arranged optionally above or below the main air line and is designated 49 and 49' respectively. The main air line 46 leads to a compressed air reservoir 50 which stores compressed air enriched with antifreezing agent.

The system illustrated in Figure 4 shows the control line 41 which leads to the anti-frosting pump 48 fitted downstream of the'pressure regulator 47. Figure 5 shows the anti-frosting pump fitted upstream of the pressure regulator 47, the control line 41 being omitted. The antifrosting pump 48 is actuated solely by the changing pressure in the main air line 46.

Figures 6 to 10 show different constructions of the pilot valve. Figure 6 shows a pilot valve 51 having a sleeve 52 which has a valve seat 53 of a valve 53/55. A closure member 55 cooperates with seat 53 and has a pushrod 56 secured thereto by means of which the closure member is raisabie from its seat 53. The valve 51 is closed upon connecting the control line 41 which allows the plunger to move to the left under the force of a spring (top portion of Figure 6). When the screw plug 33 is fitted the valve 51 is opened by way of the push rod 56 and establishes communication with the main air line 46 by way of the branch passage 34.

Figure 7 shows both types of connection having a pilot valve 61 which comprises a serving deformable valve member 62 acting as a closure member, and a housing seat 63. In a first position the valve member seats on the housing seat 63 and interrupts communication in the main air line and the pressure change chamber. Thus communication between a control line 41 and the pressure change chamber 21 is established. The valve member 62 has openings in the body portion remote from the seating to permit through flow of air. A pushrod 64 of a blanking plug serves to actuate the valve such that the closure member is displaced from the housing seat 63 to establish communication between the passage leading to the main air line and the pressure change chamber. It will be appreciated that a simple valve 61 of this kind cannot be switched back.

Figure 8 shows a pilot valve 66 having a tilting member 67 and a housing seat 68. Here also, a push rod 69 serves to actuate the valve 66. The pilot valve 66 also cannot be switched back. The operation is similar to Fig. 7 in that in a first position communication is established in a control line and the pressure change chamber in accordance with a circuit arrangement of the type illustrated in Fig. 4 and in a second position, communication is established between a main air line and the pressure change chamber, corresponding to a circuit illustrated in Fig. 5.

Figure 9 shows a further pilot valve 71 which has a valve seat 72 on a ring 73 fitted in the housing 1. The closure member 74 carries a pin 75 which can cooperate with a push rod. This pilot valve 71 is tiltabie and can be switched between first and second positions to establish communication between the pressure change chamber and the appropriate line depending on the type of circuit to which the anti-frosting device is fitted.

Figure 10 shows an even simpler construction of a pilot valve. In this instance, a compression member 77 acts as the closure member of a pilot valve 76 and is in the form of a flexible tube which, upon connection of the control line 41 (top portion of Figure 10), produces the tubular axial connection by rigid abutment against a housing seat 78. However, the compression member 77 has axial play upon the screwing-in of the screw plug 33, so that air can flow from the branch passage 34 around the circumference of the flexible tube and past the inner end face thereof to the pressure-change chamber 22.

Claims

1. An anti-frosting pump for automatically introducing an anti-freezing agent into a compressed air passage having a pressure regulator therein, the anti-frosting pump comprising a pump housing, an air pressureoperated pump piston movable in a pump cylinder in the housing against the force of a spring for displacing the anti-freezing agent into the air passage, and a pilot valve which is selectively operable to apply a fluctuating pressure to the pump piston either from an auxiliary port or from a branch passage leading from said air passage, the auxiliary port being separately connectible to the pressure regulator if the anti-frosting pump is downstream thereof or being blanked off if the pump is upstream of the pressure regulator.

2. An anti-frosting pump as claimed in claim 1, in which the pilot valve is actuable by a screw plug which is insertable into the auxiliary port.

3. An anti-frosting pump as claimed in claim 1 or 2, in which the pilot valve is a slide valve.

4. An anti-frosting pump as claimed in claim 1 or 2, in which the pilot valve is a seat valve.

5. An anti-frosting pump as claimed in claim 2, 3 or 4, in which a closure member of the pilot valve is actuable by the screw plug.

6. An anti-frosting pump as claimed in claim 5, in which the closure member is a deformable member.

7. An anti-frosting pump as claimed in claim 5, in which the closure member is a tipping member.

8. An anti-frosting pump as claimed in claim 6, in which the defor.mable member is a metal.

9. An anti-frosting pump as claimed in claim 6, in which the deformable member is a nonresilient hollow member.

10. An anti-frosting pump as claimed in claim 6, in which the deformable member is a resilient flexible tube member.

11. An anti-frosting pump constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.