GB2619328A - Hydraulic pump and braking system - Google Patents

Abstract

A hydraulic pump comprising a pressure valve housing 6 in which a pressure valve 40 is arranged, a piston 10 and a suction valve 36. A filler piece 44 is provided with a single channel 64 defining a flow path for braking fluid between the suction valve 36 (inlet valve) and the pressure valve 40 (outlet valve). The channel 64 may include two perpendicular channel parts 68, 72 and may include a first end 56 fluidly connected to the suction valve 36 and a second end 60 fluidly connected to the pressure valve 40. The filler piece 44 may also include a piston channel 52. There may be a guide sleeve 32 including a working space 14 for the piston 10, which is fixed to the filler piece 44. Also claimed is a hydraulic braking system comprising at least on hydraulic calliper connected to the hydraulic pump.

Description

Description

Hydraulic pump and braking system The invention relates to a hydraulic pump according to the preamble of claim 1. It furthermore relates to a corresponding hydraulic braking system.

Hydraulic pumps, especially hydraulic piston pumps, have a variety of applications.

These pumps are for instance applied in hydraulic or electro-hydraulic braking systems in which the pump can generate braking pressure to support the driver during a braking manoeuvre.

In some hydraulic pumps, the suction valve is not incorporated in the pump. In the pumps in which it is incorporated, different channels/rooms are created in the pump to allow the fluid to travel from the suction valve to the pressure valve. The route of the fluid from one valve to the other valve is made through several channels which need to be interconnected. The flow can be routed between pump components and can be hindered by the design of the geometry of components and/or by the assembly process.

These pump designs can affect the fluid flow and the overall performance of the pump and can require a significant space in order to function properly.

The document DE 10 2005 034 571 Al discloses an electro-hydraulic pump aggregate which consists of non-stepped piston with a compression room defined between suction valve and pressure valve.

The object of the invention is therefore to provide a pump which improves the pump performance. Another object is to provide an improved braking system.

With respect to the hydraulic pump, this object is solved in that the filler piece is provided with a single channel defining a flow path for braking fluid between the suction valve and the pressure valve.

Preferred embodiments of the invention are described in the dependent claims and

in the description.

The invention is based on the consideration that in common pump design a reduction of their efficiency is reduced by hindrances and/or deviations in the flow path of braking fluid from the suction valve to the pressure valve.

Applicant has found that the efficiency of the hydraulic pump can be improved with a pump design in which the fluid travel from the suction valve to the pressure valve is built using the shortest, i.e., most direct, route. This is achieved by using a pump filler piece which only has one channel for the fluid travel in order to avoid any additional channels or rooms where the fluid would be wasted. The pump provided therefore is a high efficiency aligned pump.

Preferably the channel in the filler piece comprises a first end fluidly connected to 20 the suction valve and a second end fluidly connected to the pressure valve.

In a preferred embodiment, the channel comprises two channel parts which are aligned perpendicular with respect to each other. The channels can alternatively be aligned at different angles, as long as the shortest fluid path is realized and continuous flow with reduced turbulences of the fluid which helps levelling the pressure across the channel thus improving the volume flow of the pump. The volume of the channel should be dimensioned in such a way that the compression ratio of the pump is maximized improving the pump efficiency.

The filler piece is advantageously made steel, aluminium or plastic.

In a preferred embodiment, the hydraulic pump comprises a guide sleeve or guiding aid in which a working space for the piston is built. The guide sleeve is preferably mounted in the pump interface / valve block and the filler piece is preferably assembled in the guide sleeve. The guide sleeve is preferably made of plastic, ceramics or metal.

The filler piece is preferably fixed to the guide sleeve by a press-fit connection which allows an easy implementation. In a preferred alternative embodiment, the filler piece is fixed to the pump housing by a threaded assembly, a non-rotation geometry, or a glue connection.

In a preferred embodiment, the single channel has a cross section between suction valve and pressure valve which is a best fit given the fluid flow and expected pump efficiency. A piston channel built in the filler piece preferably corresponds to the cross section of the piston. i.e it deviates as little as possible from the piston cross section.

With regards to the braking system, the object stated above is solved by a braking system comprising at least one hydraulic calliper fluidly connected to a at least one hydraulic pump described above.

The advantages of the invention are especially as follows. A better pump compression ratio is provided by having only one channel and the shortest route for the fluid to travel from one valve to the other. This means that the number of dead areas for fluid/air to accumulate is lower.

A better fluid travel due to less friction is realized. Using one big channel is more efficient than using several smaller channels with the same volumetric capacity because the flow result won't be the same. This is normally affected by the surface quality and fluid's viscosity but having only one channel and the shortest route for the fluid to travel from one valve to the other instead of several channels with additional connection channels or chambers generates a better travel for the fluid because the number of channel walls and corners are reduced which translates into less friction for the fluid on the route.

The pump leads to a cost reduction as from the machining point of view, it takes less time to machine only one channel on the filler piece. The proposed design leads to a size reduction and a weight reduction. The pump can be a viable solution in the fields of automotive, aeronautics, medical or pharmaceutical fields.

A preferred embodiment of the invention is described in connection with a schematic drawing in which FIG. 1 shows a hydraulic pump in a preferred embodiment in a longitudinal section, and FIG. 2 shows components of the hydraulic pump according to FIG. 1.

Same pads are labelled in all figures with identical reference numbers.

In FIG. 1, a hydraulic pump 2 is shown in a lateral section which can be used for transportation of braking fluids in hydraulic braking systems. The hydraulic pump 2 comprises a pressure valve housing 6 and a piston 10 which is axially moveable in a working chamber 14. The piston 10 is surrounded by an axially fixed piston sealing 18. In a valve block 46 (only partly shown in the figure) , a return spring 22 for the piston 10 is arranged.

For supporting the return spring 22, at an end 26 of the piston 10 which is facing the power unit (not shown in the FIGs), a spring carrier 30 is arranged which allows initial loads of the return spring 22. The spring carrier 30 or washer is fixed at the end of piston 10. The working chamber 14 is built in a guide sleeve 32 which is mounted in a pump interface 78 being retained by the deformed material. The pressure valve housing 6, and the guide sleeve 32 are both fixed in the pump interface 78.

The hydraulic pump 2 comprises a suction valve 36 and a pressure valve 40 which are both arranged in the valve block 46. The pressure valve 40 which is arranged in the pump interface 78 and the suction valve arranged in the SV (suction valve) interface are interconnected with a connection bore.

For the optimization of the efficiency of the hydraulic pump 2, a filler piece 44 is assembled in the guide sleeve 32 which is arranged in the pump interface 78.

In order to prevent containments which can be present in the braking fluid to reach the pressure valve 40, the filler piece 44 optionally comprises a sieve 48. The sieve 48 is preferably made of plastic, ceramics or metal.

The hydraulic pump 2 provides high efficiency. To this end, the hydraulic pump 2 is designed to provide a most direct flow path of the braking fluid from the suction valve 36 to the pressure valve 40. This means that a minimal or the shortest flow path between these two valves 36, 40 is realized. This is achieved by the design of the filler piece 44 which only has one channel 64 for the fluid travel in order to avoid any additional channels or rooms where the fluid would be wasted, see FIG. 2, which displays the two valves 36, 40 and two representations of the filler piece 44, in which the right representation is a longitudinal cut through the filler piece 44.

Further in FIG. 2, a piston channel 52 in the filler piece 44 is displayed which supports the flow of the fluid from the suction valve 36 to the pressure valve 40.The channel 64 is fluidly connected at a first end 56 to the suction valve 36 and at a second end 60 the pressure valve 40. The two ends 56, 60 are fluidly connected via the piston channel 52 which defines part of a flow path of channel 64 for the braking fluid from suction valve 36 to pressure valve 40. The channel 64 in the preferred embodiment shown comprises two channel parts 68, 72 meeting in an imaginary point 76 in the figure and which are rectangularly aligned with respect to each other.

The channel 64 in this way provides a direct and defined flow path for the braking fluid between the suction valve 36 and the pressure valve 40. The filler piece 44 requires a certain orientation/alignment during assembly as the piston channel 52 of the filter piece 44 must be aligned with a channel coming from / connection of the suction valve 36 in order to assure the flow path or channel 64.

The piston channel 52 preferably has a cross section which is as close as possible to the diameter of piston 10.

List of reference numerals 2 hydraulic pump 6 pressure valve housing piston 14 working chamber 18 piston sealing 22 return spring 26 end spring carrier 32 guide sleeve 36 suction valve pressure valve 44 filler piece 46 valve block 48 sieve 52 piston channel 56 first end 60 second end 64 channel 68 channel part 72 channel part 76 imaginary point 78 pump interface

Claims (10)

1. Claims 1. Hydraulic pump (2), comprising a pressure valve housing (6) in which a pressure valve (40) is arranged, further comprising a piston (10) and a suction valve (36), whereby a filler piece (44) is provided, characterized in that said filler piece (44) is provided with a single channel (64) defining a flow path for braking fluid between said suction valve (36) and said pressure valve (40).
2. 2. Hydraulic pump (2) according to claim 1, whereby said channel (64) in said filler piece (44) comprises a first end (56) fluidly connected to said suction valve (36) and a second end (60) fluidly connected to said pressure valve (40).
3. 3. Hydraulic pump (2) according to claim 2, whereby said channel (64) comprises two channel parts (68, 72) which are aligned perpendicular with respect to each other.
4. 4. Hydraulic pump (2) according to one of the claims 1 to 3, whereby said filler piece (44) is made of plastic, ceramics or metal.
5. 5. Hydraulic pump (2) according to one of the previous claims, comprising a guide sleeve (32) in which a working space (14) for the piston (10) is built.
6. 6. Hydraulic pump (2) according to claim 5, whereby said guide sleeve (32) is made of plastic, ceramics or metal.
7. 7. Hydraulic pump (2) according to one of the previous claims 1 to 6, whereby said filler piece (44) is fixed to said guide sleeve (32) by a press-fit connection
8. 8. Hydraulic pump (2) according to one of the claims 1 to 6, whereby said filler piece (44) is fixed to said guide sleeve (32) by threaded assembly, a non-rotation geometry, or a glue connection.
9. 9. Hydraulic pump (2) according to one of the previous claims, whereby a piston channel (52) built in the filler piece (44) has a cross section corresponding to the cross section of the piston (10).
10. 10. Hydraulic braking system, comprising at least one hydraulic calliper fluidly connected to at least one hydraulic pump according to one of the previous claims. 10