WO2020011582A1

WO2020011582A1 - Pump for the cooling circuit of a motor for vehicle.

Info

Publication number: WO2020011582A1
Application number: PCT/EP2019/067588
Authority: WO
Inventors: Stefano VITTORINI; Massimiliano Borasso
Original assignee: Meccanotecnica Umbra - S.P.A.; Sei - Servizi Per L'economia E Per L'ingegneria Srl
Priority date: 2018-07-11
Filing date: 2019-07-01
Publication date: 2020-01-16
Also published as: IT201800007110A1

Abstract

A pump (200) for the cooling circuit of a motor for vehicle comprises a seal assembly (5) comprising a mobile portion with a mobile collar (6) fixed to a rotary shaft (1), and a fixed portion with a fixed collar (7) fixed to a hollow body (3), indicator means (9) connected to the mobile portion (7) and detection means (8) connected to the fixed collar (6) in order to detect when the indicator means (9) pass in correspondence of the detection means (8) in such a way to calculate the rotational speed of the rotary shaft (1).

Description

PUMP FOR THE COOLING CIRCUIT OF A MOTOR FOR VEHICLE.

The present invention relates to a pump for the cooling circuit of a motor for vehicle.

The removal of the heat in an alternative internal combustion motor is a thermodynamic requirement because any thermodynamic cycle that transforms thermal energy in mechanical energy needs at least a first source with high temperature and a second source with low temperature. The heat removed from the first source energizes a thermodynamic fluid that produces mechanical work after a thermodynamic cycle and delivers thermal energy to the second thermal source at a lower temperature, restoring the thermodynamic conditions of the work fluid. In real conditions, there is a plurality of thermal levels with high temperature and a similar plurality of thermal sources with low temperature from/to which said heat exchange is performed.

In alternative internal combustion motors, the gases produced by the combustion of a fuel represent the high-temperature source and also the work fluid of the thermodynamic conversion cycle (Otto, Diesel, Beau de Rochas, etc.). After the combustion process, the gases increase their temperature (and pressure), expanding in the cylinder and producing a mechanical work: the expansion process reduces the temperature of the gases, exchanging thermal energy with the exterior, thus representing the plurality of high-temperature sources that give energy to the thermodynamic cycle.

The thermal energy exchange with the exterior that allows for restoring the conditions for a transformation cycle occurs by means of several complicated heat exchange phenomena that affect the cooling water of the motor, the lubrication oil, the environmental air for the conductive, convective and radiant exchanges of the metal masses and the exhaust gases that are returned to the atmosphere in the form of sensitive heat after the expansion process. Being an intrinsic process of the motor operation, the heat exchange on the cooling water is the major phenomenon that has been considered by the motor cooling technology. Fig. 1 generally shows a cooling circuit (100) of a motor (109).

The cooling circuit (100) comprises:

- a pump (101 ) that favors a pressurization of a fluid inside a hydraulic circuit that comprises a set of pipes for delivering cooling water and the motor (109) (base and cylinder-head) where the water circulates to remove the heat by means of contact with the metal walls of the motor; and

- a valve (thermostat) (102) that, when the water temperature exceeds a given value, opens the fluid circulation towards a radiator (104) that exchanges thermal energy with the exterior and restores the thermodynamic conditions of the water extracted by the pump (101 ).

When the circuit towards the radiator (104) is closed, the water is extracted and returns to the pump (101 ) according to a continuous heating sequence.

Fig. 1 shows an essential layout of the cooling circuit (100) of the motor. However, in real conditions, said cooling circuit of the motor is more complicated because it has to provide for additional motor-related thermal services on board the vehicle that comprise:

- a heating device (107) for the interior of the vehicle,

- a cooling device of the boosting air,

- a cooling device of the recirculated gases and

- a cooling device of the refrigerant fluid of the air conditioning system in liquid cooled solutions.

The hypothesis that the pump (101 ) or the thermostat (102) may not operate correctly will produce two very critical situations:

A) The pump (101 ) is stopped, generating the lack of fluid circulation and immediately overheating the metal walls of the motor (109) in contact with the water. Then the water is vaporized, touching the walls of the motor and consequently forming a steam film that prevents a heat exchange due to low coefficients of convective heat exchange. The metal masses rapidly achieve a thermal level that cannot be withstood by the metal components, such as the base and the cylinder-head, and also the internal parts (piston, piston rings, etc.).

B) The failure of the thermostat (102) does not allow the water to cool, passing through the radiator (104), and restore the extraction conditions of the pump (101 ) after the heat exchange with the exterior that occurs in the radiator. Therefore the water temperature tends to increase progressively, thus preventing or considerably reducing the cooling of the metal surfaces in contact with the fluid.

With reference to the two aforementioned phenomena, the most dynamic one (which immediately involves a critical situation) is the operating loss of the pump. In fact, the high thermal power that needs to be removed from the metal masses of the motor (approximately 1/3 -1/4 of the fuel power) favors an immediate overheating with a functional and structural loss of the motor.

When the specific power of the motor (kW/l) increases, also the power of the heat exchange increases and the overheating of the metal masses is more severe and more rapid.

In fact, with the same motor size, the increased power produces a situation in which a higher thermal power must pass through the same heat exchange surfaces that are wetted by the water. This is currently achieved by increasing the coefficient of forced convective heat exchange between water and metal masses, but the increase is not possible beyond certain values. Therefore, the increase in the power of the motor (which is the common trend in modern motors) determines a more rapid overheating and, consequently, a lower amount of time for the implementation of control actions.

A similar situation is found in the motors of vehicles used for goods transportation, which are defined as heavy duty vehicles. In fact, in heavy duty motors, the larger size of the motor that is necessary to obtain a higher propulsive power (the power increases with a volumetric dimension) does not correspond to the availability of heat exchange surfaces that increase with a dimension related with the surfaces. Therefore, heavy duty motors are also impaired by the aforementioned criticality.

The pump (101 ) is normally driven by a pulley that is driven by a flexible element (belt) that takes power from a driving pulley connected to the motor and gives power to the various auxiliary members.

Fig. 2 shows a driving pulley (1 10) actuated by the motor (109). The driving pulley (1 10) actuates a belt (1 1 1 ). The belt (11 1 ) actuates the pump (101 ), an alternator (1 12), a hydraulic power steering (1 13) and other utilities (1 14).

Fig. 3 is an axial sectional view of a portion of the pump (101 ). The pump (101 ) a rotary shaft (1 ) fixed to a rotary member (2) of the pump. The rotary shaft (1 ) is revolvingly mounted inside a hollow body (3) suitable for being fixed to the casing of the pump. A bearing assembly (4) is disposed between the rotary shaft (1 ) and the hollow body (3) to permit a rotation of the rotary shaft (1 ) relative to the hollow body (3).

The hollow body (3) comprises:

- a first shank (30) that forms a first chamber (31 ) where the bearing assembly (4) is disposed and

- a second shank (32) that forms a second chamber (33) directed towards the rotary member (2) and suitable for being filled with cooling fluid treated by the pump.

A seal assembly (5) is disposed between the first chamber (31 ) and the second chamber (32) to prevent the passing of the cooling fluid from the second chamber (32) to the first chamber (31 ).

The seal assembly (5) comprises a fixed portion comprising a fixed collar (6) fixed to the hollow body (3) and a mobile portion comprising a mobile collar (7) fixed to the rotary shaft (1 ). A first sliding ring (60) is mounted in the fixed collar (6). A second sliding ring (70) is mounted in the mobile collar (7) in such a way that the second sliding ring (70) can slide on the first sliding ring (60), proving a seal. A spring assembly (10) is disposed in the fixed collar (6) in such a way to push the first sliding ring (60) towards the second sliding ring (70).

Going back to Fig. 2, the actuation of the pump (101 ) is connected to the motion of the driving pulley (1 10) that is directly connected to the rotation of the motor (109). On the other hand, the rotational speed of the motor is continuously monitored and informed to the driver for several utilities that refer to motor operation, safety, comfort, etc.

However, the monitoring of the rotational speed of the motor (109) does not guarantee a rotation of the pump (101 ) at the desired speed ratio. The slippage, damage or any other failure of the belt (1 1 1 ) may determine situations in which the motor (109) is in rotation (the indication of the sensor of the rotational speed being informed to the driver), but the pump (101 ) remains stopped or revolves at a lower speed than the normal operation speed.

Therefore, the driver is not informed about the failure due to a poor circulation of refrigerating fluid, if any, and will notice the failure only when the water temperature of the motor increases because of the overheating of the metal masses. So, evidently, a direct measurement of the rotational speed of the pump (101 ) can prevent the risk of operating the motor without fluid circulation, immediately informing the driver of the failure.

The purpose of the present invention is to eliminate the drawbacks of the prior art by disclosing a pump for cooling circuit of a vehicle that is capable of providing information on the rotational speed of the pump in a precise, efficient and versatile way.

Another purpose of the present invention is to disclose such a pump for cooling circuit of a vehicle that provides information on the rotational speed of the pump without changing the structure of the pump.

These purposes are achieved according to the invention with the characteristics of the independent claim 1.

Advantageous embodiments of the invention appear from the dependent claims.

The pump for cooling circuit of a motor is defined in claim 1. The advantages of the pump according to the invention are evident, because it provides information on the rotational speed of the shaft of the pump in a precise, effective and versatile way, without changing the structure of the pump and regardless of the rotational speed of the motor of the vehicle.

Additional features of the invention will appear clearer from the detailed description below, which refers to merely illustrative, not limiting embodiments, wherein:

Fig. 1 is a diagrammatic view of a cooling circuit of a motor for a vehicle according to the prior art;

Fig. 2 is a diagrammatic view of a belt transmission of the motor of the vehicle according to the prior art;

Fig. 3 is an axial sectional view of a portion of a pump of the cooling circuit of a motor of a vehicle according to the prior art;

Fig. 4 is a perspective view of a portion of the pump according to the invention;

Fig. 5 is an axial sectional view of the portion of the pump of Fig.4;

Fig. 6 is the same axial sectional view as Fig. 4, without the rotary shaft of the pump;

Fig. 7 is a perspective view of the seal assembly of the pump of Fig.

4;

Fig. 8 is an axial sectional view of the seal assembly of Fig. 7;

Fig. 9 is an axial sectional view of a portion of a pump according to a second embodiment of the invention that is provided with an optical sensor;

Fig.10 in an enlarged detail of Fig. 9; and

Fig.1 1 is a bottom perspective view of the mobile portion of the mechanical seal of Fig. 1 1.

With reference to Figs. 4 to 8, the pump according to the invention is disclosed, which is generally indicated with reference numeral (200). In the following description the parts that are identical or correspond to the parts described above are identified with the same numerals, omitting their detailed description.

The fixed collar (6) has a bottom surface (65) in distal position relative to the sliding ring (60). The bottom surface (65) of the fixed collar supports the spring assembly (10) that pushes the first sliding ring (60).

Indicator means (9) are disposed in the mobile portion of the mechanical seal and detection means (8) are disposed in the fixed portion of the mechanical seal in order to detect the indicator means (9).

The detection means (8) are disposed on the bottom surface (65) of the fixed collar and are directed inwards, i.e. towards the shaft of the seal.

The mobile collar (7) comprises a shank (74) that is forcedly inserted on the rotary shaft (1 ) in such a way to fix the mobile collar (7) to the rotary shaft (1 ).

The indicator means (9) comprise at least one tongue (90) fixed to the shank (74) of the mobile collar in such a way to protrude from the shank (74) of the mobile collar in parallel direction to the axis of the rotary shaft (1 ) in correspondence of the detection means (8). For illustrative purposes, two tongues (90) can be disposed in diametrically opposite positions.

The detection means (8) are suitable for detecting the moment when said tongue (90) passes in correspondence of the detection means (8).

Advantageously, the detection means (8) can be a Hall-effect magnetic sensor .In such a case, the tongues (90) are magnets or made of magnetic material.

Obviously, the detection means (8) can comprise other types of sensors, such as optical sensors, capacitive sensors and the like.

The detection means (8) are electrically connected to a transmitter (80) disposed on the fixed collar (6). The transmitter (80) is suitable for transmitting a signal (such as an impulse) every time a tongue (9) passes in correspondence of the detection means (8). In view of the above, a software program can count the number of signals transmitted by the transmitter (80) in the time unit and calculate the rotational speed of the rotary shaft (1 ).

The detection means (8) and the transmitter (80) can be two chips mounted on a PCB fixed to the bottom surface (65) of the fixed collar. The transmitter (80) can be integrated in the detection means (8).

The transmitter (80) is operatively connected to a receiver (82) disposed on the hollow body (3) and directed towards the exterior of the hollow body (3). For illustrative purposes, electrical cables (81 ) connect the transmitter (80) to the receiver (82). The electrical cables (81 ) pass in a chamber (35) of the hollow body in which there is no water, due to the seal assembly (5) and pass through the hollow body (3) in order to be connected to the receiver (82).

Alternatively, the transmitter (80) can be connected to the receiver (82) in wireless mode.

The receiver (82) can be mounted on a PCB (83) fixed to the hollow body (3). A power supply (84) is mounted on the PCB (83) and connected to the transmitter (80) and to the detection means (81 ) by means of electrical cables (81 ) in order to provide power supply.

The receiver (82) is connected to a control unit that is suitably configured in order to calculate the rotational speed of the rotary shaft (1 ) of the pump.

Figs. 9 - 1 1 show a pump according to a second embodiment of the invention, which is generally indicated with reference numeral (300).

In the pump (300) the detection means (8) are an optical sensor (180).

The optical sensor (180) is disposed in an internal lateral wall (66) of the fixed ring. The optical sensor (180) has a sensitive portion that is directed towards the second sliding ring (70).

The indicator means (9) are a mark or groove (190) obtained in the second sliding ring, in such a way to be detected by the optical sensor (180). With reference to Fig. 1 1 , a ring (165) supports the optical sensor (108). The ring (165) is fixed to the internal lateral wall (66) of the fixed ring.

The internal lateral wall (66) of the fixed ring comprises a plurality of recessed seats (67). Similarly, the ring (165) is provided with a plurality of recessed seats (166) that are engaged in the recessed seats (67) of the fixed ring.

Advantageously, the optical sensor (108) is disposed in one of the recessed seats (166) of the ring.

Numerous equivalent variations and modifications can be made to the present embodiments of the invention, which are within the reach of an expert of the field and fall in any case within the scope of the invention as disclosed by the attached claims.

Claims

1. Pump (200; 300) for the cooling circuit of a motor for vehicle, said pump comprising:

- a hollow body (3) suitable for being fixed to a casing of the pump;

- a rotary shaft (1 ) revolvingly mounted in the hollow body (3); and - a seal assembly (5) disposed between a first chamber (31 ) and a second chamber (33) of the hollow body (3) in order to prevent the passing of a cooling fluid from the second chamber (33) to the first chamber (31 ) of the hollow body;

seal assembly (5) comprising:

- a fixed portion comprising a fixed collar (6) fixed to the hollow body

(3) and provided with a first sliding ring (60); and

- a mobile portion comprising a mobile collar (7) fixed to the rotary shaft (1 ) and provided with a second sliding ring (70) in such a way that the second sliding ring (70) can slide on the first sliding ring (60) to provide a seal;

characterized in that

said pump (200) also comprises:

- indicators means (9) connected to said mobile portion of the mechanical seal; and

- detection means (8) connected to said fixed collar (6) in order to detect when said indicator means (9) pass in correspondence of the detection means (8), in such a way to calculate the rotational speed of the rotary shaft (1 ).

2. The pump (200; 300) of claim 1 , wherein said pump comprises: - a transmitter (80) disposed on said fixed collar and connected to said detection means (8); and

- a receiver (82) disposed on said hollow body (3) and operatively connected to said transmitter (80).

3. The pump (200) of claim 2, wherein said transmitter (80) is connected to said receiver (82), by means of electrical cables (81 ) disposed inside a chamber of said hollow body in which no cooling fluid is contained.

4. The pump (200; 300) of claim 3, wherein said pump also comprises a power supply (84) disposed on said hollow body (3) and connected to the transmitter (80) and to said detection means (8) by means of electrical cables (81 ) in order to provide supply power.

5. The pump (200) of claim 1 , wherein the detection means (8) are disposed on a bottom surface (65) of said fixed collar in distal position relative to said sliding ring (60) and directed towards the exterior of the fixed collar.

6. The pump (200) of any one of the preceding claims, wherein said indicator means (9) comprise at least one tongue (90) connected to said mobile collar (7).

7. The pump (200) of claim 6, wherein said mobile collar (7) comprises a shank (70) inserted on said rotary shaft (1 ) and said at least one tongue (90) projects from said shank in parallel direction to the axis of the rotary shaft.

8. The pump (200) of claim 7, wherein said pump comprises two tongues (90) disposed in diametrically opposite positions.

9. The pump (200) of any one of the preceding claims, wherein said detection means (8) consist in a Hall-effect magnetic sensor and said indicator means (9) are of magnetic material.

10. The pump (300) of any one of claims 1 to 4, wherein the detection means (8) are disposed on an internal lateral wall (66) of said fixed collar and directed towards said second slide ring (70) and the indicator means (9) are disposed in said second slide ring.

11. The pump (300) of claim 10, wherein the detection means (8) are an optical sensor (180) and the indicator means (9) are a mark or groove (190) obtained in said second slide ring (70).

12. The pump (300) of claim 10, wherein said optical sensor (108) is disposed in a recessed seat (166) of a ring (165) fixed to the internal lateral wall (66) of said fixed ring.