Coolant pump arrangement for an internal-combustion engine

A coolant pump arrangement for an internal-combustion engine of a motor vehicle is provided, which includes engine shafts. The coolant pump arrangement encompasses a pump housing and a pump shaft, one end of which is provided with a pump impeller. The pump shaft is essentially cantilevered by way of a bearing that is disposed inside the internal combustion engine.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a coolant pump arrangement for an internal-combustion engine of a motor vehicle including engine shafts. The coolant pump arrangement includes a pump housing and a pump shaft, one end of which is provided with a pump impeller.

Conventionally, the required cooling of motor vehicle internal-combustion engines takes place by use of a coolant, such as water, which circulates in a coolant circulation system and absorbs heat in areas to be cooled and releases this heat again at a different point by way of heat exchangers. Pumps are provided for circulating the coolant.

German Patent document DE 199 41 891 A1, for example, describes a water pump arrangement of this type. Accordingly, the water pump has a pump housing, which is formed of a pump body and a pump covering, and which is connected with the crank case of the internal-combustion engine. The pump shaft is accommodated in the pump housing and is rotatably disposed in a shaft supporting section. The shaft supporting section has a length corresponding to three times the pump shaft diameter and is acted upon by oil for lubrication. The lubricating oil is fed from the crankcase by way of an oil feeding opening. For sealing off the pump space, a sealing device is provided, which axially adjoins the shaft supporting section.

Because of the pump shaft bearing and, in addition, as a result of the sealing device axially adjoining the latter, this water pump arrangement has a very long dimension, which may be disadvantageous, depending on the installation position, particularly when the internal-combustion engine is used in a motorcycle. Also, long coolant hoses are required for connecting the water pump.

An internal-combustion engine having an engine shaft, which is to accommodate as many components as possible relevant to the operation of the engine, is shown and described in German Patent document DE 199 45 948 A1. In addition to mass balance weights, this engine shaft accommodates an impeller on an end side for circulating coolant, the water pump housing being integrated as a function of the arrangement of the engine shaft in the crankcase or in the cylinder head.

Such an integration of the water pump arrangement in the crankcase or the cylinder head requires a high expenditure construction, for example, with a T-joint on the cylinder head, a special seal and/or additional bearings. Also, a special machining of the cylinder head is required, and the pump arrangement cannot be uncoupled.

It is, therefore, an object of the invention to further develop a cooling pump arrangement of the above-mentioned type with a view to a compact, short internal-combustion engine, particularly for a use in a motorcycle, while simultaneously providing a simple and maintenance-friendly construction.

This object is achieved by a coolant pump arrangement for an internal-combustion engine of a motor vehicle including engine shafts, having a pump housing and a pump shaft with a pump impeller arranged on one end, wherein an essentially cantilevered bearing of the pump shaft is provided by a bearing arranged inside the internal-combustion engine. The basic idea is the essentially cantilevered bearing of the pump shaft by way of a bearing arranged within the internal-combustion engine. According to the invention, the bearing is arranged inside the internal-combustion engine in the cylinder head or in the crankcase.

Particularly preferred embodiments and further developments of the invention are described and claimed herein.

According to a particularly advantageous embodiment of the invention, the pump shaft is non-rotatably and coaxially connected with an engine shaft driving it, particularly with a camshaft. The rotational water pump speed and, thus also the pumping capacity, are therefore directly dependent on the rotational speed of the internal-combustion engine. According to another embodiment, the pump shaft is drivable indirectly or directly by another engine shaft.

The bearing of the pump shaft expediently takes place by way of the last engine shaft bearing arranged adjacent to the pump arrangement. If the pump shaft is connected with a camshaft, the last camshaft bearing is simultaneously the bearing element for the pump shaft carrying the pump impeller.

In a preferred embodiment of the invention, a sealing device, particularly a slide ring seal, is arranged between the pump housing and the pump shaft, by which slide ring seal, a centering takes place simultaneously. The slide ring seal is further developed in the manner of a tube section and, by way of its radially interior surface seals off against the pump shaft. By way of its radially exterior surface the sealing device is supported on the inside radius of a receiving device on the pump housing, on the one side, and in a centering manner on the inside radius of a receiving device on the crankcase, on the other side.

It is considered to be very expedient for fixing the pump impeller and the pump shaft on the engine shaft by way of a screwed connection to construct the pump shaft to be hollow and the engine shaft to have a thread on an end side. In this case, the pump shaft is centered on the inside and the outside on the engine shaft.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1illustrates a coolant pump arrangement100for an internal-combustion engine of a motor vehicle (not shown here in detail). In this case, shown is an in-line four-cylinder engine for a motorcycle. On the face-side, the coolant pump arrangement100is connected with the cylinder head102of the internal-combustion engine, the internal-combustion engine being installed transversely to the driving direction, so that the individual cylinders are situated side-by-side with the head inclined diagonally toward the front. The coolant pump arrangement100is therefore arranged on the left in the driving direction. The charging of the cylinders takes place by intake connection pieces150,152,154,156from above, while the combustion exhaust gases are discharged diagonally downward to the front. Correspondingly, the intake camshaft for operating the intake valves158,160,162,164is situated at the top.

The coolant pump arrangement100includes a suction connection piece168, through which coolant, such as cooling water, is taken in by way of the thermostat166of the radiator170. In the area172, the coolant is fed to the water cooling jacket, in which case a distribution of the coolant flow takes place into a main flow for cooling the cylinder head102and a partial flow for cooling the crankcase. If a cooling of the internal-combustion engine, for example, during the warm-up phase, is not (yet) required, the coolant will flow, corresponding to a forward flow control, on the basis of a thermostat position, while bypassing the radiator170, directly by way of the short-circuit connection piece174back to the suction connection piece168. Only when a defined temperature has been reached, will the thermostat166control the short-circuit flow such that the suction connection piece168is acted upon while including the radiator170by way of the pipe176.

FIG. 2is a sectional view of a detail of a coolant pump arrangement200for an internal-combustion engine of a motor vehicle. The coolant pump arrangement200is connected on the face side with the cylinder head202of the internal-combustion engine and takes in coolant through a suction connection piece222. The delivery side of the radial flow pump has the reference number226. For the bearing of the camshafts, the cylinder head202has shell-type bearings which receive the camshafts. The bearings are closed by means of bearing bridges (not shown here). The figure shows the last bearing220on the end side of the intake camshaft204adjacent to the cam224.

The coolant pump shaft206is coaxially connected with the intake camshaft204. In this case, a screw through the hollow coolant pump shaft206in a thread228at the camshaft end provides a frictional connection between the pump impeller218, the pump shaft206and the camshaft204. A centering of the pump shaft206takes place as above on the camshaft on the inside or, as an alternative, on the outside. The coolant pump housing214is equipped with a pressed-in standard sliding ring seal212and is screwed to the cylinder head202, in which case the housing of the slide ring seal212is used for centering to the camshaft bearing axis in the cylinder head202. The coolant pump cover216is connected with the coolant pump housing214. The cylinder-head-side oil tightness is achieved by way of a shaft sealing ring208pressed in between the coolant pump bearing cover210and the cylinder head202.

The bearing220of the intake camshaft204, which is the last at the end side and is adjacent to the cam224, is simultaneously the bearing element for the cantilevered pump shaft206carrying the pump impeller218. A separate bearing for the pump shaft206is therefore not required, so that the length of the internal-combustion engine may be reduced considerably. Particularly in the case of an in-line four-cylinder system installed transversely into a motorcycle, this represents a significant improvement. Because of the compact dimension and the resulting small projected area in the driving direction, special advantages are achieved with respect to aerodynamics, consumption, acceleration and final speed. Furthermore, the required space, weight and costs are reduced. Particularly on the basis of the installation position, which is transversely and diagonally inclined toward the front, a connection can be established by way of very short hoses between the radiator and the cylinder head202arranged directly behind it, or the coolant pump. In addition to the above-mentioned advantages, there are also advantages with respect to the design.