GB2026089A - Radial piston pump - Google Patents

Abstract

A radial piston pump has several pistons 9 arranged in a housing and driven by an eccentric 19 to draw in a pressure medium from a suction chamber 17 and deliver it through individual non-return valves 16 into a circuit. A proportion of the pistons (9) is associated, with the pressure connection (22) of their non-return valves (16), with a separate circuit (3) which is independent of the circuit (2) of the other pistons (9). Such a pump is capable of supplying more than one circuit and resembles to the greatest possible extent a normal radial piston pump as regards the production expenditure and the overall space requirement. <IMAGE>

Description

SPECIFICATION Radial piston pump The invention relates to a radial piston pump with several pistons which are arranged in a housing and are driven by an eccentric of an eccentric shaft and slide in cylinder bores and which draw in a pressure medium from a suction chamber and deliver it into a circuit through individual non-return valves.

It is known from German Offenlegungsschrift 2436321 to use a double pump for feeding two separate circuits. This double pump consists of two individual pumps which are coupled together. Such an arrangement is expensive in production and space-consuming due to the double space requirement in the axial direction.

The task underlying the invention is to provide a radial piston pump which is capable of supplying more than one circuit and which resembles to the greatest possible extent a normal radial piston pump as regards the production expenditure and the overall space requirement.

According to the invention, this task is solved in that a proportion of the pistons is associated, with the pressure connection of their non-return valves, with a separate second circuit which is independent of the first circuit of the other pistons. Due to use being made of a radial piston pump which is normal in construction and to the distribution of the individual pistons and cylinders to at least two different circuits, it is possible to use a particularly space-saving unit which, depending on the desired application purpose, has the necessary number of pistons and cylinders. All that such a radial piston pump needs is an eccentric shaft as well as a housing, and it can be designed in a space-saving manner, particularly with respect to its axial extension, even if the delivery volume is fairly considerable.

The invention furthermore proposes, in connection with a radial piston pump wherein the non-return valves associated with the first circuit open out into a common pressure chamber which is coaxial with the eccentric shaft and wherein the cylinder bores associated with these non-return valves are radially outwardly sealed by screw plugs, that the cylinder bore or bores associated with the second circuit should in an advantageous manner communicate with the second circuit through radially outwardly fitted screw sockets having integrated non-return valves. Due to such a simple separation of the pistons and the cylinders, which are identical among themselves, merely by providing screw sockets with integrated non-return valves instead of normal screw plugs as well as by omitting a bore from the cylinder to the inwardly located pressure duct, it is possible to modify existing radial piston pumps for feeding two or more circuits with a minimum of expenditure. All that needs to be done is to connect the cylinder bores equipped with the screw sockets and the integrated non-return valves to the circuit to be supplied through a pressure connection to be fitted externally. The pump itself still has the external dimensions of a normal radial piston pump, and it is also correspondingly simple in its construction.

The invention will hereinafter be explained in more detail with reference to the exemplified embodiments shown in the drawings, in which: Figure 1 shows a representation showing the principle of a radial piston pump according to the invention with two separate circuits; Figure 2 shows a section through an exemplified embodiment of such a radial piston pump.

The radial piston pump 1 shown in Fig. 1 consists of a housing 6, in which there are provided several cylinder bores 7, 8 so as to extend approximately in a plane and radially to the eccentric shaft 1 8. The pistons 9 arranged in the cylinder bores 7, 8 are constantly held in abutting contact with the eccentric 1 9 of the eccentric shaft 1 8 by return springs 10. In the direction pointing away from the eccentric 19, these pistons 9 are each constructed so as to be open.As demonstrated by the example of the cylinder bore 8, a proportion of the cylinder bores is tightly sealed in the radial external direction by a screw plug 1 4. From the space formed by the piston 9, the cylinder bore 8 and the screw plug 1 4 there passes a pressure duct 1 3 into a pressure chamber 1 2 which is arranged in the housing 6 so as to be concentric with the eccentric shaft 1 8 and into which all the cylinder bores 8, each of which is sealed by a screw plug 14, open out. Each cylinder bore 8 comprises a non-return valve 11 which prevents any pressure medium from flowing from the pressure chamber 1 2 back into the respective cylinder chamber.A connection passes from the pressure chamber 1 2 through the housing 6 to the pressure connection 21 which is connected to the first motor 4 and forms a first circuit 2. This first circuit 2 opens out into a storage tank 24, from which a suction line 23 passes back again to the pump, namely to the suction connection 20, which is in communication with the suction chamber 1 7 which is situated in the area of the eccentric 1 9. Furthermore provided is a second circuit 3 which communicates with the cylinder bore or bores, which are designed like the cylinder bore 7 of Fig. 1.This cylinder bore 7 is passed, without interruption, radially outwardly through the housing 6 and is sealed by a screw socket 1 5. This screw socket 1 5 comprises a non-return valve 1 6 as well as a pressure connection 22. Furthermore arranged in the cylinder bore 7 as well as in the cylinder bore 8 is a piston 9 which is constantly brought to bear against the eccentric 1 9 by a return spring 1 0. The pressure connection 22 of the screw socket 1 5 is connected to a second motor 5 which is arranged in the circuit 3.Downstream of the second motor 5, this second circuit 3, too, opens out into the storage tank 24 and is also connected to the suction chamber 1 7 through the suction line 23 and the suction connection 20.

The mode of operation of the radial piston pump 1 shown in Fig. 1 is the following: The eccentric shaft 1 8 is driven from the outside and successively moves the pistons 9 to the outside against the force of the return spring 10, the windows arranged in the pistons carrying out the pressure stroke when the radially inward limitation of the cylinder bores 7 and 8 respectively is exceeded. During this pressure stroke, the pressure medium drawn in from the suction chamber 1 7 is compressed by the piston 9 in the cylinder bore 7 and, after overcoming the pre-tensioning force of the non-return valve 16, is transported past this latter into the screw socket 1 5. From this screw socket 15, the pressure medium passes through the pressure connection 22 into the circuit 3 comprising the motor 5.After leaving the motor 5, this pressure medium passes into the storage tank 24 and is drawn from there through the suction line 23 and the suction connection 20 back into the suction chamber 17. The pistons 9 arranged in the cylinder bores 8 also draw in the pressure medium from the suction chamber 1 7 and deliver it during the pressure stroke through the pressure ducts 13, past the non-return valves 11, into the pressure chamber 1 2. This pressure chamber 1 2 is arranged so as to be concentric with the eccentric shaft 1 8 and is connected through pressure ducts 1 3 to all cylinder bores 8, which deliver through the pressure connection 21 into the circuit 2. In the circuit 2, there is furthermore arranged the motor 4.

After having flowed through this motor 4, the pressure medium passes into the storage tank 24 and is transported back again through the common suction line 23.

Depending on the required amount of pressure medium, the number of the pistons 9 which are provided in the radial piston pump 1 can be distributed evenly or unevenly to the two circuits 2 and 3. In this connection, it is quite possible for only one cylinder to be connected, for example, to one circuit. It is thus conceivable that this one cylinder should be used for the additional spring suspension of a motor vehicle, while all the other cylinders supply a servo-assisted steering unit. In this connection, it may sometimes be of advantage if the individual cylinder bores have different diameters and thus deliver different amounts of pressure medium.

Fig. 2 shows a section through a constructed radial piston pump 1, all the reference numerals equalling those of the radial piston pump shown in Fig. 1. A description of the construction and the mode of operation thereof are thus unnecessary here, since they are completely identical with those of Fig. 1.

Claims (3)

1. A radial piston pump with several pistons which are arranged in a housing and are driven by an eccentric of an eccentric shaft and slide in cylinder bores and which draw in a pressure medium from a suction chamber and deliver it through individual non-return valves into a circuit, characterised in that a proportion of the pistons is associated, with the pressure connection of their non-return valves, with a separate second circuit which is independent of the first circuit of the other pistons.

2. A radial piston pump as claimed in Claim 1, wherein the non-return valves associated with the first circuit open out into a common pressure chamber, which is arranged so as to be coaxial with the eccentric shaft, and the cylinder bores associated with these non-return valves are sealed in the radially outward direction by screw plugs, characterised in that the cylinder bore or bores associated with the second circuit are connected to the second circuit through radially outwardly fitted screw sockets comprising integrated non-return valves.

3. A radial piston pump substantially as described with reference to the accompanying drawings.