Oil level sensor

Abstract

This invention provides a hydraulic level sensor that can suppress the need to increase the number of circuit configurations required in the ECU to obtain output from the oil level sensor. [Solution] The oil level sensor 10 includes a first oil level detection unit 11 that enters a first state when the oil level 8 is at or above a first oil level LV1 and enters a second state when the oil level 8 is below the first oil level LV1; a second oil level detection unit 12 that enters a first state when the oil level 8 is below a second oil level LV2 which is greater than the first oil level LV1 and enters a second state when the oil level 8 is at or above the second oil level LV2; a detection circuit 13 that outputs a detection signal indicating that the oil level 8 is normal when both the first oil level detection unit 11 and the second oil level detection unit 12 are in the first state, and a detection circuit 13 that outputs a detection signal indicating that the oil level 8 is abnormal when either the first oil level detection unit 11 or the second oil level detection unit 12 is in the second state.

Description

Technical Field

[0001] This invention relates to an oil level sensor.

Background Art

[0002] Patent Document 1 discloses an oil level sensor for detecting the oil level of oil stored in an oil pan in an internal combustion engine. The oil level sensor of Patent Document 1 includes two oil level detection circuits. One oil level detection circuit outputs a signal of L level when the oil level is below the first oil level, and outputs a signal of H level when the oil level is above the first oil level. Further, the other oil level detection unit outputs a signal of L level when the oil level is above a second oil level greater than the first oil level, and outputs a signal of H level when the oil level is below the second oil level. The electronic control unit (hereinafter referred to as "ECU (Electronic Control Unit)") of Patent Document 1 determines whether the oil level in the oil pan is normal or abnormal based on the combination of the H level and L level of the signals output from each of the two oil level detection units.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the oil level sensor described in Patent Document 1, the two oil level detection circuits are independent and separate circuits, so each of the two oil level detection circuits outputs a signal to the ECU separately. Therefore, the ECU requires a circuit configuration such as terminals to obtain the output of each of the two oil level detection circuits. In other words, the technology disclosed in Patent Document 1 requires two sets of circuit configurations such as terminals to obtain the output of each oil level detection circuit in the ECU. Having multiple circuit configurations to obtain the output from the oil level detection circuits increases the manufacturing man-hours and costs of the ECU. [Means for solving the problem]

[0005] An oil level sensor for solving the above problems is an oil level sensor for detecting the oil level in the oil pan of an internal combustion engine, comprising: a first oil level detection unit which enters a first state when the oil level is above a predetermined first oil level and enters a second state when the oil level is below the first oil level; a second oil level detection unit which enters a first state when the oil level is below a predetermined second oil level which is greater than the first oil level and enters a second state when the oil level is above the second oil level; and a detection circuit which outputs a detection signal indicating that the oil level is normal when both the first oil level detection unit and the second oil level detection unit are in the first state, and outputs a detection signal indicating that the oil level is abnormal when either the first oil level detection unit or the second oil level detection unit is in the second state. [Effects of the Invention]

[0006] With the above configuration, the detection circuit outputs a detection signal indicating whether the oil level is normal or abnormal. The ECU can determine whether the oil level is normal or abnormal by receiving the signal output by the detection circuit, thus suppressing the need for additional circuit configurations in the ECU to obtain the output from the oil level sensor. [Brief explanation of the drawing]

[0007] [Figure 1]Figure 1 is a schematic diagram showing the configuration of an internal combustion engine equipped with an oil level sensor according to one embodiment. [Figure 2] Figure 2 is a schematic diagram showing the configuration of the oil level sensor in the same embodiment. [Modes for carrying out the invention]

[0008] An embodiment of the oil level sensor will be described below with reference to Figures 1 and 2. <Overall structure of an internal combustion engine> The vehicle is equipped with an internal combustion engine 1. As shown in Figure 1, the internal combustion engine 1 is used, for example, as a power source for the vehicle. The internal combustion engine 1 comprises an internal combustion engine body 2 and an oil pan 3. The internal combustion engine body 2 has a plurality of cylinders 4. The cylinders 4 constitute a combustion chamber, which is a space for fuel to burn. Although not shown in the figure, the internal combustion engine 1 has a piston that reciprocates within the combustion chamber, an output shaft that outputs rotational torque, and a connecting rod that connects the piston and the output shaft. Fuel is injected into the cylinder 4, and the piston reciprocates in response to the combustion of that fuel. The reciprocating motion of the piston is converted into rotational motion of the output shaft by the connecting rod and the output shaft.

[0009] The oil pan 3 is fixed to the underside of the internal combustion engine body 2. The oil pan 3 stores oil 5. When the internal combustion engine 1 is in operation, the oil 5 is pumped from the oil pan 3 to various parts of the internal combustion engine body 2 by an oil pump (not shown). Specifically, the oil 5 is supplied to the pistons, connecting rods, output shafts, etc. of the internal combustion engine body 2 for purposes such as lubrication and cooling. The oil 5 used for lubrication and cooling flows from the internal combustion engine body 2 back into the oil pan 3.

[0010] Incidentally, the oil level 8 of the oil 5 in the oil pan 3 fluctuates. Specifically, the oil level 8 decreases as the oil 5 evaporates. Also, the oil level 8 rises when fuel from the internal combustion engine 1 mixes with the oil 5. For example, if the fuel from the internal combustion engine 1 is heavy, the fuel mixed with the oil 5 will not evaporate easily, causing the oil level 8 to rise more easily.

[0011] As shown in Figure 2, it is preferable that the oil level 8 of the oil 5 in the oil pan 3 be maintained at or above the first oil level level LV1 and below the second oil level level LV2. The first oil level level LV1 is predetermined. The first oil level level LV1 is defined, for example, as the height of the oil level 8 below which, if the oil level 8 falls, there is a risk that various parts of the internal combustion engine body 2 may not be adequately lubricated. The second oil level level LV2 is predetermined as a value greater than the first oil level level LV1. The second oil level level LV2 is defined, for example, as the oil level when a certain amount less than the maximum amount of oil 5 that can be stored in the oil pan 3 is stored.

[0012] As shown in Figure 1, the vehicle is equipped with an ECU 6. The ECU 6 controls the internal combustion engine 1. More specifically, the ECU 6 controls the ignition timing, fuel supply, and opening and closing timing of the intake and exhaust valves of the internal combustion engine 1.

[0013] The ECU6 includes a processing circuit and a memory device (not shown). The processing circuit consists of a CPU that executes processing according to a program and its peripheral circuits. The memory device consists of a ROM where the program is stored, a volatile RAM on which data can be temporarily written, and a non-volatile storage device on which data can be written. The memory device stores information related to the control of the internal combustion engine 1.

[0014] The vehicle is equipped with a warning device 7. The ECU 6 is electrically connected to the warning device 7. The warning device 7 warns of abnormalities occurring in the internal combustion engine 1 by means of messages, light, sound, etc. When an abnormality occurs in the internal combustion engine 1, the ECU 6 outputs a signal to the warning device 7 indicating the abnormality.

[0015] <Oil level sensor> As shown in Figure 1, the vehicle is equipped with an oil level sensor 10. The oil level sensor 10 detects the oil level 8 of the oil 5 in the oil pan 3 of the internal combustion engine 1. More specifically, as shown in Figure 2, the oil level sensor 10 is a sensor for detecting whether the oil level 8 is at or above the first oil level level LV1 and below the second oil level level LV2, that is, whether it is in a normal state.

[0016] As shown in Figure 2, the oil level sensor 10 includes a first oil level detection unit 11, a second oil level detection unit 12, and a detection circuit 13. The first oil level detection unit 11 enters a first state when the oil level 8 is at or above the first oil level level LV1, and enters a second state when the oil level 8 is below the first oil level level LV1. The second oil level detection unit 12 enters a first state when the oil level 8 is below the second oil level level LV2, and enters a second state when the oil level 8 is at or above the second oil level level LV2. The detection circuit 13 outputs a detection signal indicating that the oil level 8 is normal when both the first oil level detection unit 11 and the second oil level detection unit 12 are in the first state. The detection circuit 13 outputs a detection signal indicating that the oil level 8 is abnormal when either the first oil level detection unit 11 or the second oil level detection unit 12 is in the second state.

[0017] The first oil level detection unit 11 includes a float 14 with a specific gravity less than that of the oil 5, and a guide unit 15 installed inside the oil pan 3. The float 14 moves vertically by floating on the oil 5. The guide unit 15 restricts the horizontal movement of the float 14. The guide unit 15 is, for example, box-shaped and houses the float 14. The oil 5 from the oil pan 3 flows into the guide unit 15. The float 14 moves vertically inside the box-shaped guide unit 15 according to the oil level 8 of the oil 5.

[0018] In the first oil level detection unit 11, the state in which the float 14 is on the upper part of the guide part 15 corresponds to the first state, which is the ON state, and the state in which the float 14 is not on the upper part of the guide part 15 corresponds to the second state, which is the OFF state. The state in which the float 14 is on the upper part of the guide part 15 is, for example, the state in which the float 14 is in contact with the upper inner end of the box-shaped guide part 15.

[0019] The guide portion 15 of the first oil level detection portion 11 is positioned with respect to the oil pan 3 such that when the oil level 8 is at or above the first oil level LV1, the float 14 floating on the oil level 8 is at the upper portion of the guide portion 15.

[0020] The second oil level detection portion 12 is positioned above the first oil level detection portion 11 inside the oil pan 3. The basic configuration of the second oil level detection portion 12 is common to that of the first oil level detection portion 11. That is, the second oil level detection portion 12 has a float 14 and a guide portion 15. The guide portion 15 of the second oil level detection portion 12 is positioned above the guide portion 15 of the first oil level detection portion 11 inside the oil pan 3.

[0021] In the second oil level detection portion 12, the state where the float 14 is at the lower portion of the guide portion 15 corresponds to the on state as the first state, and the state where the float 14 is not at the lower portion of the guide portion 15 corresponds to the off state as the second state. The state where the float 14 is at the lower portion of the guide portion 15 is, for example, a state where the float 14 is in contact with the lower end inside the box-shaped guide portion 15.

[0022] The guide portion 15 of the second oil level detection portion 12 is positioned with respect to the oil pan 3 such that when the oil level 8 is less than the second oil level LV2, the float 14 floating on the oil level 8 is at the lower portion of the guide portion 15.

[0023] When both the first oil level detection unit 11 and the second oil level detection unit 12 are ON, the oil level 8 of the oil 5 in the oil pan 3 is at or above the first oil level level LV1 and below the second oil level level LV2. When either the first oil level detection unit 11 or the second oil level detection unit 12 is OFF, the oil level 8 of the oil 5 in the oil pan 3 is either below the first oil level level LV1 or at or above the second oil level level LV2. Specifically, when the first oil level detection unit 11 is OFF, the amount of oil 5 stored is insufficient. When the second oil level detection unit 12 is OFF, the amount of oil 5 stored is too much, and there is a risk that the oil level 8 of the oil 5 may rise excessively high when fuel mixes with the oil 5.

[0024] The detection circuit 13 includes a first switch circuit 16 that operates in conjunction with the first oil level detection unit 11, and a second switch circuit 17 that operates in conjunction with the second oil level detection unit 12. Although not shown in the figures, the first switch circuit 16 is composed of, for example, a switch element that can be switched on or off, and a resistor connected in parallel to the switch element. Similarly, the second switch circuit 17 is composed of a switch element that can be switched on or off, and a resistor connected in parallel to the switch element. The first switch circuit 16 and the second switch circuit 17 are formed as an integrated circuit. For example, the switch element of the first switch circuit 16 and the switch element of the second switch circuit 17 are connected in series.

[0025] The switch element of the first switch circuit 16 turns on when the first oil level detection unit 11 is ON, and turns off when the first oil level detection unit 11 is OFF. The switch element of the second switch circuit 17 turns on when the second oil level detection unit 12 is ON, and turns off when the first oil level detection unit 11 is OFF.

[0026] The detection circuit 13 is connected to a DC power supply (not shown). This DC power supply may be the same as, for example, the DC power supply for the ECU 6. The detection circuit 13 outputs a signal based on the voltage of the DC power supply. The detection circuit 13 outputs a detection signal indicating that the oil level 8 is normal when both the first switch circuit 16 and the second switch circuit 17 are on. The detection circuit 13 outputs a detection signal indicating that the oil level 8 is abnormal when either the first switch circuit 16 or the second switch circuit 17 is off. In one example, the detection circuit 13 is configured such that its output voltage differs depending on whether both the first switch circuit 16 or the second switch circuit 17 are on or off. That is, the detection circuit 13 outputs the potential of the connection node to the ECU 6 as a detection signal.

[0027] The oil level sensor 10 is equipped with a connector 19. The connector 19 is electrically connected to the detection circuit 13. The connector 19 can be connected to a connector 21 provided on the ECU 6. The connector 21 on the ECU 6 is an example of a circuit configuration for obtaining the output of the oil level sensor 10 in the ECU 6.

[0028] When the ECU 6 receives a detection signal indicating an abnormality from the oil level sensor 10, it outputs an abnormality signal to the warning device 7. In response, the warning device 7 issues a warning through means such as a message, light, or sound. The warning device 7 does not issue a warning if it has not received an abnormality signal.

[0029] <Operation and Effects of This Embodiment> The oil level sensor 10 outputs a detection signal from its detection circuit 13 indicating whether the oil level 8 is normal or abnormal, based on the states of the first oil level detection unit 11 and the second oil level detection unit 12. The ECU 6 can determine whether the oil level 8 is normal or abnormal by receiving the signal output by the detection circuit 13. Therefore, the circuit configuration required in the ECU 6 to obtain the output from the oil level sensor 10 only requires the connector 19 of the oil level sensor 10 and the connector 21 of the ECU 6. Thus, the number of circuit configurations required in the ECU 6 to obtain the output from the oil level sensor 10 can be suppressed. [Explanation of symbols]

[0030] 1...Internal combustion engine, 2...Internal combustion engine body, 3...Oil pan, 4...Cylinder, 5...Oil, 6...ECU, 7...Warning device, 8...Oil level, 10...Oil level sensor, 11...First oil level detection unit, 12...Second oil level detection unit, 13...Detection circuit, 14...Float, 15...Guide unit, 16...First switch circuit, 17...Second switch circuit, 19...Connector, 21...Connector, LV1...First oil level, LV2...Second oil level.

Claims

[Claim 1] An oil level sensor for detecting the oil level in the oil pan of an internal combustion engine, A first oil level detection unit enters a first state when the oil level is above a predetermined first oil level level, and enters a second state when the oil level is below the first oil level level. A second oil level detection unit enters a first state when the oil level is below a second oil level level that is a value greater than the first oil level level, and enters a second state when the oil level is at or above the second oil level level. The system includes a detection circuit that outputs a detection signal indicating that the oil level is normal when both the first oil level detection unit and the second oil level detection unit are in a first state, and outputs the detection signal indicating that the oil level is abnormal when either the first oil level detection unit or the second oil level detection unit is in a second state. Oil level sensor.

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