DE102005007839B3 - Radial piston pump with pump housing and crank chamber - Google Patents

Abstract

The radial piston pump (1) comprises a pump housing (2) in which a crank chamber (3) is located which is fed with cooling/oil material stream via a supply lead (4). There is also a press regulation valve (5) that operates together with a termination lead (6). The supply lead and termination lead are arranged together and wherein is a mixture nozzle (7) and a common suction jet pump (8). The termination push of the press regulation valve acts as a drive stream whilst the cooling/oil material stream operates as a suction stream. The mixture nozzle may operate together with a return lead (9) via which any excess fuel from the radial pump may be discharged. The mixture nozzle may be built as a Venturi nozzle.

Description

The The invention relates to a radial piston pump for a fuel injection system with a pump housing, in which a crank chamber is formed, which via a purge line with a coolant / lubricant flow is available.

A generic radial piston pumps, for example, from the DE 103 00 144 B3 known. The radial piston pump has a drive shaft which is rotatably mounted in a pump housing. The drive shaft has an eccentric portion, which is arranged in a crank chamber. On the eccentric shaft portion of the drive shaft, a cam ring is slidably mounted.

The Radial piston pump includes several in a uniform radial distance arranged to each other, pump units. Each pump unit has a radial in the pump housing longitudinally movable out Pump piston. The pump pistons lie in each case on a sliding shoe on, which is supported on the lifting ring. For this purpose, the cam ring has a number corresponding to the number of pump pistons from flattening up. By supporting the pump piston or the sliding shoes on the cam ring this will turn on a with the Drive shaft prevented. While the pump operation leads the lifting ring thus a wobbling movement, wherein the Hubringaußendurchmesser along a single circle descriptive curve moves. Due to the wobble of the cam ring There is a relative movement between the sliding surfaces of the shoe and the flats of the cam ring. Due to the relative movement arises Frictional heat which increases the fuel temperature in the crankcase.

by virtue of the ever-increasing demands on pressure generation Radial piston pumps are experiencing ever-increasing fuel temperatures in the crank room. Due to the high fuel temperatures, the lubricity is shank of the fuel greatly reduced, thereby reducing the risk of pumping increases.

The DE 44 01 074 A1 discloses a radial piston pump with a purge line so as to ensure adequate lubrication and cooling. In this case, a partial fuel quantity is continuously taken from a prefeed pump upstream of the radial piston pump and passed through the purge line through the eccentric chamber of the radial piston pump. As a result, a good lubrication of the eccentric drive is ensured and at the same time, heat of friction is removed from the crankcase via the flushing agent flow.

The flushing line is operatively connected to a return line through which the fuel is back in a fuel tank passes. In the return line is usually also the Absteuermenge one of the radial piston pump downstream High-pressure valve initiated. Depending on the design of the radial piston pump and dependent from the maximum diversion amount of the pressure control valve it can happen that the drainage the coolant / lubricant flow is hampered, or in the least favorable Case of fuel from the return line is pressed into the flushing line. The frictional heat then can not be removed from the crankcase. The fuel warmed up in the crankcase This greatly increases the lubrication properties of the fuel let down and the risk of pumping again increases.

at further increasing pressure requirements with respect to the radial piston pump It may also be necessary for the coolant / lubricant flow to be so high chosen he must be over the maximum Absteuermenge the pressure control valve is located. In this case can the coolant / lubricant flow in turn hinder the control of the pressure control valve, whereby a correct pressure control of the radial piston pump is hindered.

task The present invention is therefore a radial piston pump to provide, at the safe heat removal from the crankcase of the Radial piston pump at high Absteuermengen the pressure control valve, based on the coolant / lubricant flow, guaranteed is and at the same time a safe control of the pressure control valve at a high coolant / lubricant flow, in relation to the amount of tax deducted.

The Task is solved through the independent ones claims 1 and 2.

advantageous Embodiments of the invention, which individually or in combination can be used with each other, are characterized in the subclaims.

The invention comprises a radial piston pump for a fuel injection system with a pump housing, in which a crank chamber is formed, which is supplied via a purge line with a coolant / lubricant flow, and with a pressure control valve, which communicates with a Absteuerleitung in operative connection, wherein the purge line and the Absteuerleitung are designed and arranged such that they open into a mixing nozzle and together form an ejector, and wherein the Absteuermenge the pressure rule valve as a propulsion jet and the cooling / lubricant flow acts as a suction jet. By such an arrangement of purge line and Absteuerleitung is safely avoided that at large maximum Absteuermengen fuel is forced into the purge line, thereby hindering the flow of coolant / lubricant flow. On the contrary, a high maximum diversion amount of the pressure regulating valve even improves the outflow of the coolant / lubricant quantity, since in this way a larger suction effect is produced by the amount of exhausting force acting as propelling jet.

The The invention also includes a radial piston pump for a fuel injection system with a pump housing, in which a crank chamber is formed, which via a purge line with a coolant / lubricant flow can be supplied, as with a pressure control valve, which with a Absteuerleitung is in operative connection, wherein the purge line and the diversion line are designed and arranged in such a way that that they are in a mixing nozzle flow and together form a suction jet pump, wherein the coolant / lubricant flow as a propulsion jet and the Absteuermenge of the pressure control valve as Suction jet acts. Such a design and arrangement of the flushing and Absteuerleitung guaranteed that at a big one Coolant / lubricant flow the Absteuerung the pressure control valve is not hindered. The large coolant / lubricant flow even cares for an improved drainage the Absteuermenge from the Absteuerleitung because due to the large coolant / lubricant flow a high suction effect by acting as a propellant jet coolant / lubricant flow is achieved.

A advantageous embodiment of the invention provides that the mixing nozzle with a Return line is in operative connection, about the excess fuel discharged from the radial piston pump is. A common return line guaranteed a particularly compact design of the radial piston pump.

According to the invention preferred is the nozzle as a Venturi nozzle educated. The Venturi nozzle It is characterized by being behind the narrowest cross-section has a diffuser. As a result, flow energy in pressure energy converted so that the fuel at low speed in drain the fuel tank can.

By the embodiment of the invention and Arrangement of the flushing line and the Absteuerleitung is thus in a surprisingly simple manner guaranteed that at high maximum from tax amounts of the pressure control valve, the Flow away the coolant / lubricant flow from the purge line not hindered. The higher the outflow quantity the pressure control valve is, the cheaper this is due to the amplified Suction on the outflow the coolant / lubricant flow out.

is a particularly high coolant / lubricant flow required, the purge line can and the diversion line according to the invention also designed and be arranged that the coolant / lubricant flow acts as a propulsion jet and thus no negative impact on the Absteuermenge the pressure control valve exerts. At high coolant / lubricant flows is the Absteuermenge due to the higher suction on the contrary even positively influenced.

embodiments The invention will be described below with reference to the schematic drawings explained. It shows:

1 an axial section through a radial piston pump according to the invention; and

2 : a detailed view of in 1 illustrated suction jet pump.

Same or functionally identical components are cross-figurative with the same Provided with reference numerals.

1 shows an axial section through a radial piston pump according to the invention 1 , The radial piston pump 1 includes a pump housing 2 in which rotatably a drive shaft 10 is stored. The drive shaft 10 has a flying end section 11 on, on which a prefeed pump 12 is arranged. As pre-feed pump 12 For example, a vane pump is suitable. The pre-feed pump 12 sucks fuel from a fuel tank (not shown) and delivers it to a suction port of the radial piston pump 1 , The drive shaft 10 has an eccentric shaft section 14 on, in one in the pump housing 2 trained crank room 3 is arranged. On the eccentric shaft section 14 is a lifting ring 15 slidably mounted. The radial piston pump 1 comprises a plurality of pump units arranged at a uniform radial distance from one another 17 of which only one is completely visible in the sectional view. Every pump unit 17 has a radial in the pump housing 2 longitudinally movably guided pump piston 13 , The pump pistons 13 each lie on a sliding block 16 at the hub ring 15 supported. For this purpose, the cam ring 15 one of the number of pump pistons 13 corresponding number of flattenings. By supporting the pump piston 13 or the sliding shoes 16 at the stroke ring 15 this is at a co-rotating with the drive shaft 10 prevented. During one revolution of the drive shaft 10 leads the stroke ring 15 just a tumbling motion. Because of the Tumble Elbe movement of the cam ring 15 There is a relative movement between the cam ring 15 and the sliding shoe 16 , Due to the relative movement frictional forces occur, whereby frictional heat in the crankcase 3 arises, which ensures an increase in the crankcase temperature. Due to the rising temperature in the crankcase 3 will be in the crank room 3 heated fuel heats. As a result, the lubricating property of the fuel decreases. To prevent this, a part of the pre-feed pump 12 to the radial piston pump 1 subsidized fuel branched off and via a purge line through the crankcase 3 guided. This results in a continuous replacement of the fuel in the crankcase 3 instead of. The heat is from the fuel from the crankcase 3 dissipated.

The one from the crank room 3 outgoing part 4 the purge line is connected to a return line 9 in operative connection, via the excess fuel from the radial piston pump 1 discharged and directed back to the fuel tank.

The radial piston pump 1 further comprises a pressure regulating valve 5 , The pressure control valve 5 is the pump units 17 the radial piston pump 1 downstream. When exceeding a preset fuel pressure in the high pressure part opens the pressure control valve 5 and it becomes a Absteuermenge in a Absteuerleitung 6 discharged, whereby the pressure in the high pressure part drops to the predetermined pressure. The diversion line 6 is also in operative connection with the return line 9 , which leads the fuel back to the fuel tank. The flushing line 4 and the diversion line 6 are designed and arranged such that they are in a mixing nozzle 7 lead and together a suction jet pump 8th formed. The formation of the suction jet pump and its function will be described below with reference to 2 explained in more detail.

2 shows a detail view of in 1 shown suction jet pump 8th , The suction jet pump 8th is from the purge line 4 and the diversion line 6 educated. The diversion line 6 opens coaxially in the flushing line 4 , At high Absteuermengen the pressure control valve 5 occurs the Absteuermenge with high kinetic energy from the Absteuerleitung 6 and thereby forms a propulsion jet. At the exit of the diversion line 6 is the mixing nozzle 7 arranged in the mixes the Absteuermenge with the outer coaxially flowing coolant / lubricant flow. It transmits part of the kinetic energy to the coolant / lubricant flow. As a result, the coolant / lubricant from the crankcase 3 sucked. The coolant / lubricant flow acts as a suction jet. Due to the design and arrangement of the flushing line 4 and the diversion line 6 in the form of a suction jet pump 8th the outflow of the coolant / lubricant flow from the purge line 4 even at high Absteuermengen the pressure control valve 5 not negatively affected. On the contrary, due to the discharge amount acting as a propulsion jet, the outflow of the coolant / lubricant flow is even positively influenced.

The mixing nozzle is in 2 designed in the form of a venturi. This is followed by a diffuser at the narrowest nozzle cross-section 18 at. The diffuser 18 converts part of the velocity energy into pressure energy. As a result, the flow velocity is reduced and the fuel can at a lower speed on the return line 9 be returned to the fuel tank. Of course, the mixing nozzle 7 be formed in a different design, without departing from the scope of the invention.

In the event that to the radial piston pump 1 special requirements are made in terms of cooling and lubrication and the coolant / lubricant flow is always greater than the maximum Absteuermenge the pressure control valve 5 so can the purge line 4 and the diversion line 6 be arranged so that the coolant / lubricant flow acts as a propulsion jet and the Absteuermenge as a suction jet. The flushing line 4 and the diversion line 6 are opposite the 2 then arrange only reversed. Since the other structure of such a suction jet pump 8th opposite to the 2 does not change anything shown, no further figure is required for understanding.

The flushing line 4 and the diversion line 6 are thus designed and arranged such that they open into a mixing nozzle and together a suction jet pump 8th form. Depending on the requirements of the radial piston pump 1 and depending on the Absteuermenge and the coolant / lubricant flow can either act as the Absteuermenge or the coolant / lubricant flow as a propulsion jet. By the described design and arrangement of the purge line 4 and the diversion line 6 is an unimpeded flow of coolant / lubricant flow from the purge line 4 or unimpeded Absteuern the Absteuermenge of the pressure control valve 5 guaranteed at all times. This increases the reliability of the radial piston pump 1 , The radial piston pump 1 is particularly suitable for common-rail fuel injection system where particularly high demands are placed on the pressure generation, which leads to increased temperature loads of the crankcase.

Claims (4)

Radial piston pump ( 1 ) for a fuel injection system with a pump housing ( 2 ), in which a crankcase ( 3 ) is formed, which via a Purge line ( 4 ) can be supplied with a coolant / lubricant flow, as well as with a pressure regulating valve ( 5 ), which with a Absteuerleitung ( 6 ) is in operative connection, wherein the flushing line ( 4 ) and the diversion line ( 6 ) are designed and arranged such that they are in a mixing nozzle ( 7 ) and together a suction jet pump ( 8th ), wherein the Absteuermenge the pressure control valve ( 5 ) acts as a propulsion jet and the cooling / lubricant flow as a suction jet. Radial piston pump ( 1 ) for a fuel injection system with a pump housing ( 2 ), in which a crankcase ( 3 ) is formed, which via a purge line ( 4 ) can be supplied with a coolant / lubricant flow, as well as with a pressure regulating valve ( 5 ), which with a Absteuerleitung ( 6 ) is in operative connection, wherein the flushing line ( 4 ) and the diversion line ( 6 ) are designed and arranged such that they are in a mixing nozzle ( 7 ) and together a suction jet pump ( 8th ), wherein the cooling / lubricant flow as a propulsion jet and the Absteuermenge the pressure control valve ( 5 ) acts as a suction jet. Radial piston pump according to claim 1 or 2, characterized in that the mixing nozzle ( 7 ) with a return line ( 9 ) is operatively connected via the excess fuel from the radial piston pump can be discharged. Radial piston pump according to one of the preceding claims, characterized in that the mixing nozzle ( 7 ) is designed as Venturi nozzle.