Compressor for a kit for inflating and / or repairing tyres

Abstract

A compressor for inflating tyres, comprising a direct current electric motor (E), a pump driven by the electric motor (E), a USB socket or plug for the electric power supply of the electric motor (E), preferably a USB-C, and a time-varying resistance arranged in series between the electric motor (E) and the USB plug or socket, so as to reduce the resistance during operation of the electric motor (E) and avoid peaks of current consumed, while keeping the current consumed below a predetermined threshold.

Description

Technical Field

[0001] The present invention relates to a compressor for inflating and preferably repairing vehicle tires. Background Technology

[0002] Tire inflation and repair kits are known in the art and are commonly used when vehicle tires are damaged by punctures, for example, from sharp objects encountered while driving.

[0003] In addition to the option of using a spare tire, puncture assist kits are stored in vehicles for weight reduction purposes and can be used in place of a spare tire when a tire is damaged. These kits typically include a compressor for generating compressed air and sealant introduced into the punctured tire. The sealant required by such a kit can be applied manually by the user, in which case the compressor performs the single function of inflating the tire, or applied with the assistance of the compressor, in which case the compressor performs two functions: injecting the liquid sealant and subsequently inflating the tire. In particular, one kit configuration is known in which a container of liquid sealant is connected to the tire, and the sealant is injected manually. After disconnecting the sealant container, the compressor is connected to the tire to be repaired to achieve a pressure suitable for vehicle operation. Because this compressor requires a power supply, current kits must be connected to the vehicle's onboard power outlet via a cable with a plug compatible with a cigarette lighter socket. Cigarette lighter sockets are increasingly being replaced by USB, particularly USB-C. Furthermore, the power supplied using this new power outlet is 20V and 5A, providing 100W. While this power level may be improved in the future, this configuration currently represents the prevailing standard. This power is insufficient to meet at least one of the conditions for the tire compressor's maximum current consumption: when initiating the injection of liquid sealant and when the tire's operating pressure needs to be reached, for example, 2.4 bar depending on the vehicle model. Specifically, under certain operating conditions of the compressor, the current reaches a peak of 33A consumed within milliseconds: this peak is detected by the vehicle controller, and the power supply to the USB-C socket is interrupted. This prevents the compressor from starting; that is, even if the user (e.g., by turning on a switch) intends to generate compressed air, the electric motor does not rotate.

[0004] It should also be noted that USB-C is a standard for negotiating between vehicle power outlets or power delivery: when a USB-C plug is inserted into a power PD, a constant voltage is agreed upon by the PD, and current is supplied by the PD to the user device based on the load, reaching a maximum value. In the case of a 100W PD, the maximum voltage agreed upon between the device to be powered and the PD is 20V, and the nominal current that can be delivered based on the load is 5A, as described above. Summary of the Invention

[0005] The object of the present invention is to provide a compressor for inflating tires and preferably also for repairing them, which overcomes the above-mentioned disadvantages.

[0006] The objective of this invention is achieved by the compressor according to claim 1.

[0007] It has been confirmed that controlling the rotational speed from a low initial value (i.e., low supply voltage of the electric motor) to a high value (i.e., high supply voltage) allows for limiting average current consumption and thus allows for the injection of liquid sealant and subsequent tire inflation while adhering to the safety logic of vehicle power delivery.

[0008] In particular, this invention achieves a "soft start" compatible with the vehicle's power supply because when the user turns on the electric motor to generate compressed air, the supply voltage of the electric motor gradually increases from a low initial value to a higher final value. The pump starts operating when the user actuates the electric motor (e.g., by turning on a switch) and gradually reaches its power consumption until it reaches the maximum power delivered by the power delivery module of the auxiliary circuit of the wheeled motor vehicle (e.g., car, motorcycle, four-wheeled motorcycle such as ATV-UTV, small tractor).

[0009] Furthermore, capacitors—which can be single or multiple cells and charge rapidly (e.g., in less than 2 seconds)—are capable of supplying the peak current typically required when the electric motor is turned on, powered via a voltage regulator, and the pump is under load, such as for opening a sealant container with compressed air or inflating a slightly deflated tire to the correct pressure. In particular, the voltage regulator reduces the peak current required during startup under load.

[0010] According to one embodiment, one or more capacitors supply excess peak current relative to the maximum current delivered by the power delivery module of the vehicle's auxiliary circuitry. Preferably, the capacitors are arranged immediately downstream of the compressor's socket or plug, so that they are charged immediately upon electrical connection of the compressor to the power delivery module, particularly when the electric motor is off. Referring to the figures, the size of the one or more capacitors is determined to supply a reduced peak current, i.e., a peak value obtained due to the use of a voltage changing device, which exceeds the maximum rated current supplied by the circuit, and this current must be delivered throughout the entire time when the motor requires power greater than the nominal power of the power delivery module.

[0011] In addition, capacitors are used as filters for electrical noise generated by DC electric motors, especially brushed electric motors. In this way, the highly sensitive safety logic of power delivery will not be activated, thus allowing for smooth power delivery.

[0012] Preferably, a variable resistor, such as a negative temperature coefficient (NTC) resistor, is used, which has a high value when cold (i.e., at startup), limiting the peak current to approximately 11A. This value allows the electric motor to start, albeit with lower torque. In fact, this value is tolerated by the controller of the vehicle's onboard USB-C socket. As the temperature rises due to the Joule effect, the NTC variable resistance decreases until it becomes negligible, and simultaneously, the torque required during sealant injection and to achieve the tire's operating pressure (e.g., 2.4) is also tolerated by the 100W, 20V, and 5A circuit. By appropriate sizing, the compressor of the present invention can be sized to operate at a nominal voltage not exceeding 24V or another voltage (preferably but not necessarily constant) supplied by power delivery.

[0013] The present invention provides a “soft start” that can be achieved either by pre-determined patterns of supply voltage increase over time based on empirical measurements of the compressor under various operating conditions, for example, or actively, for example by providing a microcontroller programmed to modify the operating parameters of a voltage-changing device based on current, preferably the instantaneous current consumed by the electric motor during air delivery. This change in the supply voltage to the electric motor occurs while the voltage received from the power delivery remains constant (preferably constant throughout the compressor’s entire operating cycle). Attached Figure Description

[0014] The invention will now be described in more detail with reference to the following accompanying drawings, which illustrate exemplary and non-limiting embodiments of the invention, wherein: Figure 1a The diagram illustrates a circuit diagram of a compressor according to the invention for inflating tires and preferably also for repairing them; Figure 1b The diagram shows... Figure 1a Simplified variant; Figure 2 The diagram qualitatively illustrates the reduction in current required for startup of the electric motor when a device for changing the supply voltage is used; and Figure 3 This is an exemplary view of a kit for repairing and inflating tires, the kit comprising, according to... Figure 1a or Figure 1b The circuit diagram of the compressor. Detailed Implementation

[0015] Figure 1aAlternate diagram 1b shows a basic circuit diagram of a compressor according to the invention, which includes an electric motor E and an air pump with a maximum operating pressure of up to 7 bar. The DC electric motor E (preferably brushed) and the pump are housed in a housing preferably made of plastic. The pump can be reciprocating, rotary, or of another type suitable for inflation and preferably also for injecting liquid sealants, and the compressor includes a removable flexible hose for connecting the pump outlet to a tire valve. Preferably, the compressor includes a pressure gauge for measuring the pressure in the tire via the flexible hose. Furthermore, according to the invention, the compressor includes a power cord with a USB-C plug. This cord can be non-removable, for example, threaded or crimped to the housing, or the housing may include a USB socket, preferably a USB-C socket, and the cord includes a second USB plug, preferably also USB-C, for releasable mechanical and electrical connection to the electric motor. This second option allows for the use of a cord that can be purchased independently of the compressor, for example, in the event of damage or loss.

[0016] It should be noted that the compressor of the present invention is portable and can be carried by hand (especially with one hand) by any person driving a wheeled vehicle, and is powered by the vehicle's onboard electrical source via wires, such as a 20V and 5A nominal power source, i.e., the power delivery module of the auxiliary circuit of the wheeled motor vehicle, preferably a DC power source. The auxiliary circuit powers the dashboard, interior courtesy lights, car radio, etc., and the power delivery module is powered by this auxiliary circuit, and includes: an electrical safety circuit for controlling the delivery of electrical power not exceeding the nominal value; and an electrical power socket, such as a USB port, arranged, for example, on the dashboard, for user electronic devices, such as mobile phones and the compressor of the present invention. In the case of hybrid or all-electric vehicles, the circuit is decoupled from the traction circuit, and the power delivery module of the auxiliary circuit is located inside the passenger compartment, for example in the dashboard and / or trunk.

[0017] According to one aspect of the invention, a voltage changing device is connected between the power line and the electric motor E. This voltage changing device is configured to increase the supply voltage of the electric motor E from a low value to a high value corresponding to the maximum nominal power of the power outlet, starting from a user-generated pump-on command (e.g., via electrical switch I). In this way, the electric motor has a "soft start," meaning that even under high load, it can start by initially consuming a low voltage and current and gradually increasing it. It should be noted that switch I is both manual and automatic, e.g., electronically controlled, and activates the electric motor, which can, for example, be automatically shut off via a timer that shuts off the motor when the maximum inflation time (e.g., 20 minutes) or a predetermined pressure is reached.

[0018] According to a preferred embodiment, the voltage changing device includes a variable resistor or a thermistor, and even more preferably a negative temperature coefficient variable resistor, i.e., a resistor with a high resistance value when cold, which gradually decreases during operation of the electric motor E due to the Joule effect of the current flowing through it, until ideally becoming zero. When the electric motor E is off, the resistor cools down, and its resistance value increases again. The variable resistor connected in series with the electric motor E can be implemented in other ways, for example by a rheostat, which is preferably controlled by an automatic control device configured to apply a predetermined mathematical law of resistance change over time, preferably a decrease in resistance over at least one time interval, such that during this time interval, when the pump is under high load, the current consumed by the electric motor E, particularly the peak current, is kept below a predetermined threshold and will not damage the power supply of the auxiliary circuit and / or cause the safety circuit of the power delivery module, which limits the delivered current, to be activated. The power delivery module does indeed include known safety circuits for controlling the delivered current, particularly the peak current, below a predetermined threshold so as not to damage the internal components of the power delivery module and / or the auxiliary circuit. By gradually changing the voltage, the electric motor E gradually increases its rotational speed.

[0019] According to an alternative embodiment, the supply voltage changing device includes a microcontroller and pulse width modulation (PWM) control to supply a variable supply voltage to the electric motor via a variable duty cycle controlled by the microcontroller, i.e., increasing from a low value until reaching the maximum value of the nominal supply voltage of the power delivery module. Preferably, the duty cycle frequency is greater than 1 kHz, even more preferably greater than 10 kHz, and 100% of the duty cycle corresponds to the maximum voltage, i.e., the nominal voltage of the power delivery module, such as 24V. The time-varying duty cycle variation can be set by programming the control unit.

[0020] In the frequency modulation embodiment, the startup peak current is also lower than in a configuration without supply voltage control (but in any case higher than the maximum nominal current that the power delivery module can deliver).

[0021] It should be noted that while the voltage changes regulate the angular velocity of the electric motor E, the power delivery throughout the compressor's entire working cycle (e.g., tire repair and inflation or tire inflation to working pressure) supplies a constant voltage, such as 20V, and a current depending on the pump's load during the working cycle.

[0022] refer to Figure 1aOne or more capacitors C are provided on the compressor board, which are preferably, but not exclusively, connected upstream of the switch relative to the electric motor E. A capacitor is an electrical component having electrodes separated by a dielectric, and operates as an open switch when charging and consumes current as a closed switch, for example, during charging; therefore, it is always connected in parallel with the motor relative to the power outlet / plug. In particular, the capacitor(s) charge rapidly (i.e., within 2 seconds of being connected to the power outlet) to help supply peak current when starting the pump under load. Because the capacitor supplies current at the initial moment of starting the electric motor (e.g., when the user closes the compressor's main switch I), it provides protection for the power supply circuitry and simultaneously provides sufficient current for the electric motor to start under load in the presence of voltage fluctuation devices.

[0023] Figure 1a A controlled bypass switch IB supplying the resistor of the voltage-changing device is further illustrated. This switch is closed to more quickly provide sufficient current and / or voltage to the electric motor E under specific operating conditions (e.g., when the user restarts the compressor a second time shortly after the first start). An example of this use will be described in more detail below. Preferably, the controlled bypass switch (e.g., a MOSFET) is normally open and is closed by a timer activated when the electric motor E is turned on. The timer for closing the controlled switch is set to define a time interval at which the variable resistor can cool down while the electric motor E is still operating. This allows the compressor to be restarted even shortly after the first start, thus utilizing the resistor under conditions suitable for soft start (with high resistance and therefore low temperature). Simultaneously, the controlled switch performs a gradual closing pattern, causing the voltage to increase gradually rather than in a step. When the switch is a MOSFET, the MOSFET's closing time constant allows the nominal voltage of the power delivery module to be reached within a time interval of, for example, less than or equal to 2 seconds. In most applications, the operating time of the variable resistor, starting from the moment the electric motor E is turned on, is a few seconds, such as 4 seconds, and the gradual increase in voltage (e.g., during the MOSFET's closed state when the variable resistor is bypassed) is even lower. However, there may be applications where the duration for the voltage to increase to the nominal value of the power delivery module after bypassing the variable resistor is longer than the operating time of the variable resistor. In particular, considering the gradual turn-off time of the MOSFET (i.e., comparable to the turn-off time of the NTC resistor), current continues to flow through the NTC resistor during the MOSFET's turn-off transient until the MOSFET is fully turned off.

[0024] Figure 1bOne embodiment is shown in which a variable resistor (preferably an NTC resistor) is provided, without a capacitor. According to a preferred but non-limiting embodiment, the capacitor is replaced by a buffer battery (not shown) on the compressor board, which is connected upstream of the switch relative to the electric motor E. When the battery is charged, the peak current is supplied by the battery.

[0025] Figure 3 A kit for repairing and inflating tires is shown, comprising a compressor C and a compressible liquid sealant container L with a single port (i.e., an outlet port, to which a pipe T is connected for manually injecting liquid sealant into the tire). Figure 2 In this kit, compressor C inflates the tire but does not inject liquid sealant, therefore it does not aid in tire repair. During the injection of liquid sealant, container L is not pressurized by compressor C.

[0026] According to a first embodiment (not shown), the invention is incorporated into a semi-automatic inflation and repair kit, wherein a liquid sealant container L1 includes an inlet for compressed air and an outlet for injecting liquid sealant, and a valve that closes the inlet and outlet of container L1 to preserve the liquid sealant when the kit is not in use (e.g., when placed in a vehicle compartment). A compressor C is connected to the inlet of container L1 such that the airflow generated when compressor C is activated (i.e., when the wire is connected to a vehicle power outlet) opens the valve, and the liquid sealant is injected into the tire to be repaired by pressurizing container L1 through the airflow generated by compressor C.

[0027] According to the embodiment, container L1 and compressor C are stored fluidly disconnected from each other before use, and the user must manually connect the inlets of compressor C and container L1 to form a fluid connection before repair. In the embodiment, compressor C (preferably a housing) includes a seat to which container L1 is mechanically coupled to so as to be held in the liquid sealant injection position during pressurization of the container by a pump.

[0028] According to another variant not shown, container L1 (which is also stored in the vehicle compartment) is mechanically releasably attached to this seat to maintain a fixed position relative to the compressor when stored in the vehicle compartment, when injecting liquid sealant, or when inflating the tires. Preferably, the overall dimensions of container L1, which is mechanically attached to the compressor, are parallelepiped in shape, and in this configuration, the container is both outside the compressor C and fully contained within a specific compartment of the compressor housing.

[0029] According to an embodiment not shown, the change in supply voltage (i.e., the supply voltage increasing from a low value until the nominal voltage of the power delivery module) is achieved by a device that connects a constant-value resistor and a MOSFET with a closing time of a few seconds in parallel relative to the motor E. In this manner, there is a transient period of at least 4 seconds during which the supply voltage of the motor E increases until it reaches the nominal value of the power delivery module. Preferably, when the electric motor E starts, the MOSFET is turned on, and the supply voltage of the electric motor is constant and based on a fixed resistor. After a predetermined time interval, for example controlled by a timer, the MOSFET gradually closes, for example over one second or longer, preferably two seconds or longer, and the supply voltage of the electric motor E gradually increases.

[0030] Furthermore, the timer can be implemented by any device capable of ensuring execution within a predetermined time, such as a counter, or, in the case of a MOSFET, by a capacitor with appropriate capacitance to achieve closure within the desired time interval.

[0031] It should be noted that the present invention applies to any compressor driven via a power supply data exchange port, wherein the data includes the compressor's supply voltage value, which is provided to the power delivery by a controller arranged on the compressor board or the power and data exchange board (preferably in a wired plug).

[0032] According to another embodiment, the compressor includes a controller configured to detect the current consumed by the electric motor E during operation and modify one or more operating parameters of the PWM, such as the duty cycle, based on the measured current. This change is made while maintaining a constant voltage supplied by power delivery throughout the compressor's entire operating cycle (e.g., patching a tire or inflating a tire to nominal pressure). Similarly, in embodiments providing MOSFETs, the controller controls the MOSFETs based on the consumed current.

[0033] In embodiments not shown, the means for regulating the supply voltage of the electric motor E, whether in a passive embodiment (i.e., open-loop) or an active embodiment (i.e., measuring the current consumed by the electric motor), can also be implemented in a module carried by wires.

[0034] If it is necessary to improve the performance of the electrical noise filter of motor E, a diode (preferably a freewheeling diode) can be provided in combination with the transmission.

Claims

1. A compressor for inflating a tire, comprising a DC electric motor (E), a pump driven by said electric motor (E), a socket or plug for power supply to said electric motor (E), preferably USB, and means for changing the supply voltage of said electric motor (E), said means being configured to increase said voltage from a low value to a high value from the moment said electric motor (E) is turned on to generate compressed air, so as to increase said voltage during operation of said electric motor (E).

2. The compressor according to claim 1, wherein, The voltage changing device includes a variable resistor arranged in series between the electric motor (E) and the plug or socket, wherein the reduction of resistance is variable to avoid peak current consumption while keeping the current consumption below a predetermined threshold.

3. The compressor according to claim 2, wherein, The variable resistor is configured to vary based on temperature due to the Joule effect.

4. The compressor according to claim 2 or 3, comprising a controlled bypass switch (IB), preferably a MOSFET, arranged in parallel with a variable resistor and controlled to close and bypass said resistor, preferably having a closing time of greater than or equal to 1 second for the nominal supply voltage of the power delivery module.

5. The compressor according to claim 4, wherein, The controlled bypass switch is controlled to close based on a timer activated when the electric motor (E) is turned on.

6. The compressor according to claim 1, wherein, The voltage supply device includes a PWM module for modulating the voltage of the power delivery module.

7. The compressor according to any one of the preceding claims, comprising a USB socket and a wire having a USB plug for connection to said socket, and another USB plug adapted for connection to another USB socket in a vehicle.

8. The compressor according to any one of the preceding claims, comprising at least one capacitor (C) connected in parallel with the electric motor (E) and in parallel with the socket or plug, such that when the electric motor is turned on to generate compressed air and increase its speed, a starting current defined by a voltage changing device is supplied, and such that after discharge, the electric motor (E) continues to be powered through the socket or plug, wherein, The socket or plug is used to supply power to the electric motor (E) via the power delivery module of the auxiliary circuit of the wheeled ground motor vehicle.

9. The compressor according to any one of the preceding claims, wherein, The capacitor is arranged between the switch and the socket or plug so that it is charged when the socket or plug is electrically connected to the power delivery module and the switch is in the off position of the electric motor (E).

10. The compressor according to claim 8 or 9, wherein, The capacitor has a total capacitance of less than or equal to 0.05 farads, preferably less than or equal to 0.022 farads, and a charging voltage of 20 volts.

11. The compressor according to any one of the preceding claims, wherein, The microcontroller is configured to deliver a nominal voltage to the vehicle's power supply via a USB socket or plug, which is modified during use by a voltage changing device to gradually increase the rotational speed of the motor (E).

12. The compressor according to any one of the preceding claims, comprising a mechanical coupling to a liquid sealant container, the coupling being configured to hold the container in a liquid sealant injection position when the container is pressurized via a fluid connection to a pump.

13. The compressor according to any one of the preceding claims, comprising a controller configured to control a voltage regulating device based on the current consumed by the electric motor (E) during the generation of compressed air.

14. The compressor according to any one of claims 1 to 12, wherein, The voltage regulator is configured to execute a predetermined increase pattern of the supply voltage of the electric motor (E) over time.

15. A kit for repairing and inflating a tire, comprising a compressor according to any one of the preceding claims and a container (L) for a liquid sealant to be injected into the tire.

16. The kit of claim 15, wherein, The liquid sealant container (L1) includes an inlet that can be connected to a vehicle's USB socket via a USB plug; a compressor (C) that pressurizes the container; and an outlet configured to inject pressurized liquid sealant through the compressor (C).

17. A method for inflating a tire, comprising the following steps: – Connect to the compressor (C) according to any one of claims 1 to 15; – Connect the compressor's delivery section to the vehicle's tires; – Turn on the compressor (C).

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