DESCRIPTION "Mechanical coolant pump, particularly for vehicles, and working method of the pump"

[0001] The subject of this invention is a coolant pump, i.e. a pump for circulating coolant in the cooling circuit of an internal combustion engine, in particular for vehicles.

[0002] A further subject of the invention is the working method of the coolant pump. [0003] Numerous examples of coolant pumps are well known, mechanically activated by a kinematic chain from the driveshaft or electrically, by a separate electric motor.

[0004] This invention refers, in particular but not univocally, at a mechanical action pump.

[0005] It is well known that on starting up a vehicle the coolant is at a low temperature, close to the temperature of the external ambient. In the same way the elements of the engine, and in particular the cylinder head, are at a low temperature. Only after a period of running do the elements of the engine, and consequently the coolant, reach a high temperature, tending to remain constant, corresponding to optimal functioning of the engine.

[0006] On start up a mechanical pump supplies coolant to the engine at low temperature, thus preventing fast heating of the engine and extending the interval of time after which optimal functioning is achieved.

[0007] Some embodiments, for example the one illustrated in document DE19921421A1 , provides for a deviating valve on the pump delivery which works in such a way that when engine temperature is low, part of the coolant is deviated to an outlet from which it is then sent back to the pump; when engine temperature is high the deviating valve directs the coolant towards the cooling circuit.

[0008] This pump with deviating valve however gives a low performance since a quantity of energy supplied to the pump is used for recirculation of the coolant not delivered to the cooling circuit.

[0009] The purpose of this invention is to provide a mechanical action coolant pump, in particular for vehicles, which satisfies the above requirements while overcoming the inconveniencies of the state of the art.

[0010] This purpose is achieved with a mechanical coolant pump made according to claim 1. The subsequent claims describe variants of embodiment.

[0011] The characteristics and advantages of the pump according to this invention will be evident from the description below, which is given solely by way of example and is not limitative, according to the attached figures in which:

[0012] - figures 1a and 1b disclose a pump according to this invention and according to an embodiment, respectively in a closure configuration and in an open configuration;

[0013] - figures 2a and 2b disclose a pump according to this invention and according to another embodiment, respectively in a configuration of closure and in an open configuration;

[0014] - figures 3a and 3b show a pump according to this invention and according to yet another embodiment, respectively in a closure configuration and in an open configuration;

[0015] - figures 4a and 4b illustrate a pump according to this invention and according to another embodiment, respectively in a closure configuration and in an open configuration.

[0016] With reference to the attached figures, number 1 indicates overall a mechanical coolant pump, in particular for vehicles, according to this invention.

[0017] Pump 1 comprises a pump body 2 and an impeller 4 housed in pump body

2, for example of a substantially circular form.

[0018] Pump body 2 is connectable to the engine cooling circuit and in particular connectable to a duct of circuit upstream from which the liquid is drawn in, and to a duct of circuit downstream by which the liquid under pressure is delivered to the engine.

[0019] Impeller 4, set in rotation around an impeller rotation shaft, is such as to take in the liquid from the upstream circuit and send it under pressure to the downstream circuit.

[0020] Downstream of the impeller, pump body 2 has a delivery chamber 6 with a spiral progression and a delivery conduit 8 which extends from delivery chamber 6.

Delivery chamber 6 and delivery conduit 8 have no other apertures towards other conduits except the opening of the delivery conduit to the downstream duct of the cooling circuit.

[0021] In particular, from a point on the edge of the impeller, proceeding circumferentially, the delivery chamber has a passage section radially and progressively wider, linking up with delivery conduit 8 which has a rectilinear delivery axis X, for example parallel to a tangent at a point of the impeller.

Perpendicularly to delivery axis X, delivery conduit 8, in the direction of the progress of the liquid, has an increasing section of passage.

[0022] Pump 1 further comprises a shutter valve, created for example with a shutter

10 turning around a shutter rotation shaft, suitable for limiting on command the passage of liquid from delivery chamber 6 to delivery conduit 8.

[0023] In particular, the shutter valve is suitable, in closure configuration, for obstructing the passage from delivery chamber 6 to delivery conduit 8, limiting or preferably preventing the passage of liquid from the delivery chamber to the delivery conduit (figure 1a).

[0024] In other words, when the shutter valve is in closure configuration, delivery chamber 6 is closed and the liquid remains therein, agitated by the rotating impeller.

[0025] In the closure configuration, though on the basis of laboratory tests a quantity of liquid still remains in the delivery conduit, almost all of it remains in the delivery chamber, undergoing a swirling remixing due to the action of the impeller.

[0026] In a configuration of full opening the shutter valve permits the passage of the greatest possible quantity of liquid from the delivery chamber to the delivery conduit

(figure 1b).

[0027] Preferably, between the angular position of the closure configuration and the angular position of the configuration of full opening, the rotating shutter is turned at about 45°.

[0028] Preferably, in the configuration of full opening, shutter 10 is aligned with delivery shaft X, permitting the passage of the greatest possible quantity of liquid from the delivery chamber to the delivery conduit.

[0029] Pump 1 also comprises sensors for identifying the functioning condition of the vehicle, for example heat sensors which note the coolant temperature or the temperature of the engine elements.

[0030] Moreover pump 1 comprises activating means suitable for acting on the shutter valve to take it from closure configuration to open configuration and/or vice versa.

[0031] The activating means are operationally linked to the sensor means, from which they receive signals regarding functioning condition, and to the shutter valve for activation of the said valve.

[0032] For example, the heat sensor means register the temperature of the engine elements and transmit the information to the activating means which, while the engine is cold, keep the shutter valve in the closed configuration. Progressively, with the increase of engine temperature, or according to a predefined function, the activating means take the shutter valve into the open configuration.

[0033] According to another form of embodiment, the activating means comprise a spring 12, suitable for acting continuously on the shutter 10 to keep it in the closure configuration (figures 2a and 2b).

[0034] According to yet another form of embodiment, the activating means comprise a linear actuator 14, for example the temperature sensitive wax type. The actuator 14 is engaged with shutter 10, resisting the action of the spring.

[0035] At low temperatures the actuator is withdrawn and the spring action closes the shutter valve; at high temperatures the actuator (thanks for example to the expansion undergone by the wax body) is forward and, resisting the spring, opens the shutter valve.

[0036] According to another form of embodiment, the activating means comprise a twofold effect actuator 16, hinged around shutter 10 at hinging point 18, for example at an extremity thereof (figures 3a and 3b).

[0037] Preferably the delivery conduit- 8 has a lateral bend 20 to house the extremities of actuator 16 and shutter 10 in hinging point area 18, in the closure configuration of the valve (figure 3b).

[0038] In this way, in the closure configuration, we have better obstruction of liquid transit, thus improving pump performance since the terminal duct of the shutter is in catch projection with a portion 2b of the wall of pump body 2, immediately upstream of bend 20.

[0039] According to another form of embodiment, the activating means are structured in such a way as to operate on the shutter valve to keep it normally open.

In other words, the activating means, in the absence of external actions, keep the valve in the open configuration (figures 4a and 4b).

[0040] For example, the activating means comprise a simple effect actuator 30 which can be activated in closure, meaning that under the action of closure pressure it provides for moving the shutter into the closure configuration (figure 4b).

[0041] The actuator 30 comprises a spring 32 operating in opposition to the pressure action of closure of the said actuator, which is to say compressed in such a way as to operate constantly on the actuator to bring shutter 10 into the open configuration position (figure 4a).

[0042] Advantageously, this structure means safe working conditions in the case of breakdown (failsafe design) since without closure pressure the shutter valve is open so a flow of coolant to the engine is ensured.

[0043] According to one form of embodiment, shutter 10 is a plate with a flat section, i.e. on a plane at right angles to the rotation axis of the impeller, substantially rectilinear (figure 1a).

[0044] Preferably, shutter 10 is set at the inlet of delivery conduit 8, obstructing the minimum section passage.

[0045] According to another form of embodiment, shutter 10 is hinged at a hinging point 40 in the spiral portion of delivery chamber 6 (figures 2a, 3a, 4a) .

[0046] According to one form of embodiment, shutter 10 comprises (figure 2a):

- an upstream rectilinear duct 42, parallel with a tangent to the impeller, which blocks the delivery chamber; b) an intermediate curved duct 44 which, in valve closure configuration, is close to the impeller and follows its curved progression; and c) a downstream rectilinear duct 46 which, in the valve closure configuration, is close to portion 2b of the pump body wall, in the conduit of pump 8.

[0047] According to another form of embodiment, shutter 10 comprises (figures 3a, 4a): a) an upstream curved duct 52 which blocks the delivery chamber, preferably concave on the delivery chamber side; in the full opening configuration the said duct is preferably parallel to a duct of the edge of impeller 4; b) a rectilinear duct 54 which, in the valve closure configuration, is tangent to the impeller and terminates in the delivery conduit.

[0048] Preferably, the delivery chamber has a housing 60 for the extremity . of shutter 10, for example the extremity of the upstream curved duct 52.

[0049] Advantageously, in virtue of delivery chamber housing 60, the valve considerably limits the liquid which, in closure configuration, can transit towards the delivery conduit. Advantageously, moreover, in the open configuration the transit of liquid is facilitated inasmuch as the curved duct upstream reprises the progress of the impeller and does not obstruct the flow of liquid.

[0050] This invention also concerns the working method of a coolant pump, for example created as described above.

[0051] The said working method comprises the phases of:

- setting the pump in motion and keeping the impeller rotating;

- noting the temperature of the coolant;

- if the temperature is below a threshold temperature, closing the delivery chamber towards the delivery conduit, creating a closed delivery chamber and retaining liquid therein, continuing to turn the impeller;

- if the temperature is higher than threshold temperature, opening the delivery conduit to allow liquid to pass.

[0052] Innovatively, the pump according to this invention overcomes shortcomings in the state of the art.

[0053] In particular it improves efficiency with regard to well known pumps inasmuch as no energy is wasted in the recirculation of liquid that does not reach the engine.

[0054] Innovatively, moreover, it speeds up the achievement of optimal engine heat conditions since it minimises the amount of liquid delivered to the engine in the closed configuration.

[0055] Moreover, and advantageously, in the full opening configuration the pump reduces load losses to the minimum, facilitating functioning at the correct rating.

[0056] The variants described above with reference to a specific figure are actually to be understood as being combinable with variants described in other figures.

[0057] Clearly, a specialised technician could carry out modifications to the pump described above in order to meet contingent requirements, yet without going beyond the safeguarding context defined in the following claims.