Compressor

Abstract

To provide a compressor that can continue operation while preventing sudden stalls in the main unit. [Solution] In the compressor 1, the compressor control unit 91 controls the main unit 10 and the opening / closing adjustment unit 60 based on the internal pressure of the oil chamber 20 detected by the discharge pressure sensor 83. Furthermore, when the rotational speed detected by the rotational speed sensor 81 is less than the target rotational speed, if the rotational speed control signal is maintained at W% or higher for a first predetermined period, the compressor control unit 91 sets the maximum value of the opening / closing control signal to a value obtained by subtracting X% from the initial value.

Description

Technical Field

[0001] The present invention relates to a compressor that compresses air.

Background Art

[0002] Conventionally, a compressor with an engine as the main unit has been used to compress air (see Patent Document 1). In a compressor, generally, in order to efficiently use the main unit, the power of the main unit is set so as not to be excessive with respect to the power of the air end.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the main unit suffers a slight failure or the like and falls into a power output decrease, the main unit cannot maintain the rated rotational speed, the power of the main unit is lower than the power of the compressor, and there is a risk that the main unit will suddenly stall. Further, when an alternative fuel different from the recommended fuel is used for the engine as the main unit and the assumed power output cannot be exerted, the main unit cannot reach the rated rotational speed and there is a risk of suddenly stalling.

[0005] On the other hand, since it takes time from the confirmation of the failure to the completion of the repair, there is a need to continue the operation in the case of a slight failure. Also, when alternative fuel must be used during a disaster or the like, there is a need to avoid sudden stalling and continue the operation.

[0006] The present invention has been created in view of such circumstances, and an object thereof is to provide a compressor capable of continuing operation while preventing sudden stalling of the main unit. [Means for solving the problem]

[0007] To solve the aforementioned problems, the compressor of the present invention comprises a main unit, an air end that compresses air by the rotational force of the main unit, an intake adjustment unit that adjusts the amount of air supplied to the air end, an oil chamber in which the air compressed by the air end is stored, a pressure sensor that detects the internal pressure of the oil chamber, a rotational speed sensor that detects the rotational speed of the main unit, an open / close control signal for controlling the intake adjustment unit, and a control unit that generates a rotational speed control signal for controlling the main unit, wherein the open / close control signal has a value of 0% for when the intake adjustment unit is fully closed and a value of 100% for when the intake adjustment unit is fully open, and the control unit controls the main unit and the intake adjustment unit based on the internal pressure detected by the pressure sensor, and when the rotational speed detected by the rotational speed sensor is less than the target rotational speed, if the rotational speed control signal is maintained at V% or higher for a first predetermined period, the maximum value of the open / close control signal is set to a value obtained by subtracting X% from the initial value. [Effects of the Invention]

[0008] According to the present invention, it is possible to continue operation while preventing sudden stalls of the main engine. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic piping diagram showing a compressor according to an embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view of a normally open intake control valve, where (a) shows the normal state (valve open) and (b) shows the state during operation (valve closed). [Figure 3] This is a schematic cross-sectional view of a normally closed intake control valve, where (a) shows the normal state (closed valve) and (b) shows the state during operation (open valve). [Figure 4] This graph shows an example of the relationship between the rotational speed and output of the main engine and compressor. [Figure 5] This is a flowchart illustrating an example of the operation of a compressor according to an embodiment of the present invention. [Figure 6] This is a flowchart illustrating an example of the operation of a compressor according to an embodiment of the present invention. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0011] As shown in Figure 1, the compressor 1 according to an embodiment of the present invention is a device that takes in external air, compresses it, and supplies the compressed air to an external device or the like. The compressor 1 comprises a main unit 10, an air end 20, an oil chamber 30, and a service valve 40. The compressor 1 includes a first air passage 2a and a second air passage 2b as the flow path for the compressed air.

[0012] The first air passage 2a connects the air end 20 and the oil chamber 30 in a way that allows air to flow through them. The second air passage 2b connects the oil chamber 30 and the service valve 40 in a way that allows air to flow through them.

[0013] <Main engine> The main engine 10 is the power source for the air end 20, generating rotational force to power the air end 20 and transmitting it to the air end 20. An engine, motor, or the like can be used as the main engine 10.

[0014] <Air End> The air end 20 is a compression unit (compressor body) that compresses external air using the power of the main unit 10. The air compressed by the air end is supplied to the oil chamber 30 via the first air passage 2a.

[0015] <Oil Chamber> The oil chamber 30 is a gas-liquid separation section where the air compressed by the air end 20 is stored and the oil contained in the compressed air is separated. The separated oil is returned to the air end 20 via an oil flow path (not shown).

[0016] <Service valve> The service valve 40 is a supply end for supplying the compressed air compressed by the air end 20 and stored in the oil chamber 30 to an external device or the like. The service valve 40 is configured to be openable and closable manually or based on a control signal from a compressor control unit 91 described later.

[0017] <Configuration for supplying air to the air end> The compressor 1 includes an intake adjustment valve 50 and an opening / closing adjustment section 60 as an intake adjustment section for supplying external air to the air end 20. The compressor 1 includes a third air flow path 2c as a flow path for external air. The compressor 1 includes a fourth air flow path 2d as a flow path for compressed air for operating the intake adjustment valve 50. The compressor 1 includes a fifth air flow path 2e as an exhaust flow path of the fourth air flow path 2d.

[0018] The third air flow path 2c connects the intake adjustment valve 50 and the air end 20 in a manner allowing air to flow through.

[0019] The fourth air flow path 2d connects the oil chamber 30 and the cylinder 51 (see FIGS. 2 and 3) of the intake adjustment valve 50 in a manner allowing air to flow through. In the fourth air flow path 2d, an opening / closing adjustment section 60, a check valve 71, and an orifice 72 are provided in this order from the oil chamber 30 side toward the intake adjustment valve 50 side.

[0020] The check valve 71 is a one-way valve that allows the air to flow from the oil chamber 30 side to the intake adjustment valve 50 side and prohibits the air from flowing from the intake adjustment valve 50 side to the oil chamber 30 side. Note that the check valve 71 may be provided on the intake adjustment valve 50 side of the orifice 72 in the fourth air flow path 2d, or may be provided in the fifth air flow path 2e.

[0021] The orifice 72 adjusts the flow rate of air flowing through the fourth air passage 2d. The orifice 72 is for controlling and limiting the air flow rate, and can be omitted by using a small-diameter, long hose for the fourth air passage 2d.

[0022] The fifth air passage 2e connects the cylinder 51 of the intake control valve 50 (see Figures 2 and 3) to the third air passage 2c in a way that allows air to flow through it. One end of the fifth air passage 2e may be connected to the fourth air passage 2d instead of the cylinder 51 in a way that allows air to flow through it. An orifice 73 is provided in the fifth air passage 2e.

[0023] The orifice 73 adjusts the flow rate of air flowing through the fifth air passage 2e. The orifice 73 is for limiting the air flow rate and can be omitted by making the fifth air passage 2e a small-diameter, long hose.

[0024] <Intake control valve> The intake control valve 50 is a valve that adjusts the amount of air introduced from the outside to the air end 20, i.e., the intake volume, by opening and closing according to the operating state of the compressor 1.

[0025] <Intake control valve: Normally open type> Here, as an example of an intake control valve 50, a normally open type intake control valve will be described. As shown in Figures 2(a) and 2(b), the normally open type intake control valve 50A comprises a cylinder 51, an intake port 52, a valve seat 53, a piston 54 and a biasing part 55 housed in the cylinder 51, a shaft 56 connected to the piston 54, and a valve body 57 connected to the tip of the shaft 56.

[0026] As shown in Figure 2(a), the valve body 57 is biased in the opening direction by the biasing part 55, and under normal conditions, it opens away from the valve seat 53, opening the intake port 52. In this state, external air is introduced into the air end 20 through the intake port 52 and the third air passage 2c.

[0027] As shown in Figure 2(b), when the valve body 57 is in operation, it is biased in the closing direction against the biasing force of the biasing part 55 by the compressed air supplied to the cylinder 51, and seats on the valve seat 53 to close the valve and block the intake port 52. In this state, no external air is introduced into the air end 20.

[0028] <Intake control valve: Normally closed type> Next, as an example of an intake control valve 50, a normally closed intake control valve will be described. As shown in Figures 3(a) and 3(b), the normally closed intake control valve 50B comprises a cylinder 51, an intake port 52, a valve seat 53, a piston 54 and a biasing part 55 housed in the cylinder 51, a shaft 56 connected to the piston 54, and a valve body 57 connected to the tip of the shaft 56.

[0029] As shown in Figure 3(a), the valve body 57 is biased in the closing direction by the biasing part 55, and under normal conditions, it seats on the valve seat 53 and closes the valve, blocking the intake port 52. In this state, no external air is introduced into the air end 20.

[0030] As shown in Figure 3(b), when operating, the valve body 57 is biased in the opening direction against the biasing force of the biasing part 55 by the compressed air supplied to the cylinder 51, opening the valve and moving away from the valve seat 53, thereby opening the intake port 52. In this state, external air is introduced into the air end 20 through the intake port 52 and the third air passage 2c.

[0031] <Opening / closing adjustment section> The opening / closing adjustment unit 60 is for adjusting the opening degree of the intake control valve 50, and in this embodiment, it is a proportional control valve. Based on the opening / closing control signal from the compressor control unit 91 (described later), the opening / closing adjustment unit 60 takes an appropriate opening degree, thereby converting the flow rate (pressure) of compressed air supplied from the oil chamber 30 to the cylinder 51 of the intake control valve 50 to a desired flow rate (pressure). The opening / closing adjustment unit 60, like the intake control valve 50, may be normally open or normally closed.

[0032] <Various Sensors> The compressor 1 includes a rotational speed sensor 81, a control pressure sensor 82, and a discharge pressure sensor 83.

[0033] <Rotation speed sensor> The rotational speed sensor 81 detects the rotational speed as power generated by the main unit 10 and outputs the detection result to the compressor control unit 91, which will be described later.

[0034] <Control pressure sensor> The control pressure sensor 82 detects the pressure of the compressed air supplied to the intake control valve 50 via the fourth air passage 2d and outputs the detection result to the compressor control unit 91, which will be described later. The control pressure sensor 82 is located downstream of the opening / closing adjustment unit 60 and the orifice 72 (on the intake control valve 50 side) and detects the pressure of the compressed air adjusted by the opening / closing adjustment unit 60.

[0035] <Discharge pressure sensor> The discharge pressure sensor 83 detects the pressure of the compressed air stored in the oil chamber 30 and outputs the detection result to the compressor control unit 91, which will be described later.

[0036] <Various Control Units> The compressor 1 includes a compressor control unit 91 and a main unit control unit 92 as its control components.

[0037] <Compressor Control Unit> The compressor control unit 91 is a control unit composed of a CPU (Central Processing Unit), ROM (Read-Only Memory), RAM (Random Access Memory), input / output circuits, and the like.

[0038] The compressor control unit 91 uses the detection result of the discharge pressure sensor 83 to refer to a first lookup table pre-stored in the compressor control unit 91. The first lookup table stores the detection result of the discharge pressure sensor 83 and the value of the on / off control signal in association. Based on this reference result, the compressor control unit 91 generates an on / off control signal to set the detection result of the control pressure sensor 82 to a predetermined value, and outputs the generated on / off control signal to the on / off adjustment unit 60. Through this control, the compressor control unit 91 can convert the pressure of the compressed air in the oil chamber 30 to an appropriate level and supply air at the appropriate pressure to the cylinder 51 of the intake control valve 50. The on / off control signal output by the compressor control unit 91 to the on / off adjustment unit 60 is set so that the value at which the intake control valve 50 is fully closed is 0%, and the value at which the intake control valve 50 is fully open is 100%, regardless of whether the intake control valve 50 is normally closed or normally open.

[0039] The compressor control unit 91 uses the detection result of the discharge pressure sensor 83 to refer to a second lookup table pre-stored in the compressor control unit 91. The second lookup table stores the detection result of the discharge pressure sensor 83 and the value of the rotation control signal in association. Based on this reference result, the compressor control unit 91 generates a rotation speed control signal to set the detection result of the control pressure sensor 82 to a predetermined value, and outputs the generated rotation speed control signal to the main engine control unit 92. The rotation speed control signal output by the compressor control unit 91 to the main engine control unit 92 sets the no-load minimum rotation speed value, which is the value for rotating the main engine 10 at the lowest rotation speed under no-load conditions, to 0%, and the no-load maximum rotation speed value, which is the value for rotating the main engine 10 at the highest rotation speed under no-load conditions, to 100%. If the detection result of the rotation speed sensor 81 does not reach the predetermined rotation speed even after a predetermined time has elapsed, the compressor control unit 91 may correct the target rotation speed of the rotation speed control signal by adding or multiplying the rotation speed control signal by a predetermined correction value.

[0040] The compressor control unit 91 can independently or in conjunction with the control of the opening / closing adjustment unit 60 using the opening / closing control signal and the control of the main unit 10 using the rotational speed control signal.

[0041] <Main engine control section> The main engine control unit 92 is a control unit composed of a CPU, ROM, RAM, input / output circuits, etc. The main engine control unit 92 acquires the rotational speed control signal generated by the compressor control unit 91 and controls the main engine 10 based on the acquired rotational speed control signal. If the main engine 10 is an electronically controlled engine, an ECU (Electronic Control Unit) can be used as the main engine control unit 92. If the main engine 10 is a motor, an inverter can be used as the main engine control unit 92.

[0042] <Control method by compressor control unit> When the user starts the compressor 1 by operating an operating unit (not shown), completes a predetermined warm-up operation, and the service valve 40 is closed, the compressor control unit 91 controls the main engine 10 and the opening / closing adjustment unit 60 to store air compressed to a preset pressure in the oil chamber 30. Specifically, the compressor control unit 91 outputs a rotation control signal to the main engine control unit 92, which controls the main engine 10, so that the target rotation speed (rated rotation speed a (see Figure 4)) corresponding to the detection result of the discharge pressure sensor 83 matches the rotation speed of the main engine 10 detected by the rotation speed sensor 81. The target rotation speed is set so that the lower the internal pressure of the oil chamber 30 detected by the discharge pressure sensor 83, the higher the target rotation speed. At the same time, the compressor control unit 91 outputs an opening / closing control signal to the opening / closing adjustment unit 60 so that the detection result of the discharge pressure sensor 83 reaches the set pressure. These controls open the intake control valve 50, and the internal pressure of the oil chamber 80 increases due to pressurization by the air end 20. When the pressure in the oil chamber 30, detected by the discharge pressure sensor 83, reaches the set pressure, the rotational speed of the main engine 10 becomes the no-load operating speed, and the intake control valve 50 is controlled to the fully closed position (see Figure 2(b) or Figure 3(a)). In this no-load operating state (see Figure 4c), the user can make compressed air available by opening the service valve 40.

[0043] Furthermore, the output of the air end 20 at its rated rotational speed a on power line B is set to approximately 90% of the output of the main engine 10 at its rated rotational speed a on power line A1 (see Figure 4).

[0044] <Output reduction occurs> If the output of the main engine 10 decreases or the load on the air end 20 increases during rated operation, the rotational speed of the main engine 10 will not be able to maintain the rated rotational speed a, and will decrease to rotational speed b. Furthermore, the air pressure discharged from the service valve 40 will also no longer be able to maintain the rated pressure (see power line A2 of the main engine 10 during output reduction shown in Figure 4). If the air pressure required by the user's load decreases, the rotational speed of the main engine 10 can increase to rotational speed a. However, rotational speeds above rotational speed b force the main engine 10 to operate without sufficient output margin (e.g., 100% operation), accelerating the deterioration of the main engine 10.

[0045] <Method 1 for setting the maximum opening of the intake control valve> The compressor control unit 91, when the rotational speed detected by the rotational speed sensor 81 is less than the rated rotational speed a, sets the maximum value Wmax of the on / off control signal to a value obtained by subtracting X[%] (X>0, for example, 10[%]) from the initial value W[%] of the maximum value (for example, 100[%], 95[%] or more, etc.) for a first predetermined period T1 (for example, 60 seconds). The predetermined percentage V[%] is a value based on the aforementioned rotational speed control signal values, i.e., 100[%] as the theoretical maximum value of the rotational speed control signal (maximum rotational speed value under no load) and 0[%] as the minimum rotational speed value under no load. The maximum value Wmax, the initial value W (or Winit, described below)[%], and X[%] are based on a value where the open / close control signal value when the intake control valve 50 is fully open is set to 100[%], and the open / close control signal value when the intake control valve 50 is fully closed is set to 0[%].

[0046] In this case, the compressor control unit 91 replaces the maximum value Wmax of the on / off control signal from the initial value W as follows. Wmax=WX Next, the compressor control unit 91 generates an open / close control signal between 0 and Wmax[%] to control the open / close adjustment unit 60.

[0047] According to this setting method, if the power generated by the main engine 10 is insufficient for the power required by the air end 20 due to a minor malfunction, use of alternative fuel, etc., and the rotational speed of the main engine 10 falls below the rated rotational speed in order to maintain the rated pressure (when transitioning from power line A1 to power line A2 in Figure 4), the maximum opening of the intake control valve 50 can be reduced. When the maximum opening of the intake control valve 50 is reduced, the discharge volume of the air end 20, that is, the amount of air compressed by the air end 20, decreases, and the power of the air end 20 decreases. Because the power required by the air end 20 falls below the power generated by the main engine 10, the main engine 10 can return to the rated rotational speed while maintaining the rated pressure. In this state, the compressor 1 can continue to supply air compressed to the rated pressure while reducing the discharge volume, and can avoid operating conditions that place a burden on the main engine.

[0048] <Method for setting the maximum opening of the intake control valve, part 2> Following the above-mentioned settings, the compressor control unit 91, when the rotational speed detected by the rotational speed sensor 81 is less than the rated rotational speed a, sets the rotational speed control signal to a value obtained by subtracting Y[%] (Y>0, for example, 15[%], or the same value as X) from the current maximum value Wmax of the open / close control signal, if the rotational speed detected by the rotational speed sensor 81 is less than the rated rotational speed a, and the rotational speed control signal is maintained at a predetermined percentage V[%] or higher (for example, 100[%], 95[%] or higher) for a second predetermined period T2 (for example, 60 seconds, which may be a different value from the first predetermined period T1). Y[%] is a value based on a value where the value of the open / close control signal when the intake control valve 50 is fully open is 100[%] and the value of the open / close control signal when the intake control valve 50 is fully closed is 0[%].

[0049] In other words, the compressor control unit 91 repeatedly calculates and replaces the maximum value Wmax of the on / off control signal as follows. Wmax(next value) = Wmax(current value) - Y

[0050] According to this setting method, even if the power generated by the main engine 10 remains insufficient for the power required by the air end 20 after the first predetermined period T1 has elapsed, and the rotational speed control signal of the main engine 10 continues to exceed a predetermined percentage V[%] (often when both the internal pressure of the oil chamber 30 and the rotational speed of the main engine 10 decrease), the maximum opening of the intake control valve 50 can be repeatedly reduced. As a result, the power required by the air end 20 falls below the power generated by the main engine 10, allowing the main engine 10 to return to its rated rotational speed while maintaining its rated pressure.

[0051] <Method 3 for setting the maximum opening of the intake control valve> When starting compressor 1, the user selects either the normal fuel operation mode or the alternative fuel operation mode as the operating mode by operating an operating unit (not shown).

[0052] When the normal operation mode is selected, the compressor control unit 91 performs opening and closing control with the maximum value of the opening and closing control signal Wmax[%] set to W[%]. When the alternative fuel operation mode is selected, the compressor control unit 91 performs opening and closing control with the maximum value of the opening and closing control signal Wmax[%] set to WZ[%]. Z[%] is a value based on a value where the value of the opening and closing control signal when the intake control valve 50 is fully open is set to 100[%] and the value of the opening and closing control signal when the intake control valve 50 is fully closed is set to 0[%].

[0053] According to this setting method, if a decrease in the power of the main engine 10 is predictable due to an intentional factor other than a malfunction, the maximum opening of the intake control valve 50 can be restricted in advance. This allows the compressor 1 to pre-shift to an operating point where the power generated by the main engine 10 is sufficient for the power required at the air end 20.

[0054] <Example of operation> Next, we will explain an example of the operation of compressor 1 with reference to the flowcharts in Figures 5 and 6 (refer to Figures 1 to 3 as appropriate).

[0055] An operating unit (not shown) outputs the operating mode of the compressor 1 based on the user's operation of the operating unit (step S1). Here, the operating mode includes whether or not the fuel of the engine as the main unit 10 is normal fuel.

[0056] If the compressor control unit 91 indicates that the operating mode is normal fuel (Yes in step S1), it sets the initial value Winit of the maximum value of the on / off control signal to W[%] (step S2A).

[0057] On the other hand, if the compressor control unit 91 indicates that the operating mode is not normal fuel (i.e., alternative fuel) (No in step S1), it sets the initial value Winit, the maximum value of the on / off control signal, to WZ[%] (step S2B). For example, if W=100[%] and Z=10[%], Winit is set to 100-10=90[%].

[0058] After step S2A or step S2B is executed, the compressor control unit 91 sets the maximum value Wmax of the on / off control signal to the initial value Winit (step S3), and outputs a rotation speed control signal to the main engine control unit 92, thereby causing the main engine control unit 92 to operate the main engine 10 (step S4).

[0059] Next, the compressor control unit 91 determines whether the current rotational speed detected by the rotational speed sensor 81 is less than the rated rotational speed (step S5). If it is determined that the current rotational speed is equal to or greater than the rated rotational speed (No in step S5), this flow returns to step S5.

[0060] On the other hand, if it is determined that the current rotational speed is less than the rated rotational speed (Yes in step S5), the compressor control unit 91 determines whether the rotational speed control signal is greater than or equal to a predetermined percentage V[%] (for example, 100%) (step S6). If it is determined that the rotational speed control signal is less than V[%] (No in step S6), this flow returns to step S5.

[0061] On the other hand, if it is determined that the rotational speed control signal is V[%] or higher (Yes in step S6), the compressor control unit 91 measures the duration tc during which the rotational speed control signal is at 100% (step S7).

[0062] Next, the compressor control unit 91 determines whether the maximum value Wmax[%] of the on / off control signal is Winit[%] and whether the duration tc is greater than or equal to the first predetermined period T1 (step S8A). If the answer in step S8A is Yes, the compressor control unit 91 subtracts X[%] from the maximum value Wmax[%] of the on / off control signal, adds 1 to the alarm count, and sets the duration tc to zero (step S9A). This alarm count is the number of times the timing for either the first predetermined period T1 or the second predetermined period T2 of the duration tc has been repeated.

[0063] On the other hand, if the answer in step S8A is No, the compressor control unit 91 determines whether the maximum value Wmax[%] of the switching control signal is less than Winit[%] and whether the duration tc is greater than or equal to the second predetermined period T2 (step S8B). Here, the cases in step S8A where the answer is No include when it is determined that the maximum value Wmax[%] of the switching control signal is less than Winit[%] and when it is determined that the duration tc is less than the first predetermined period T1.

[0064] If the answer in step S8B is Yes, the compressor control unit 91 subtracts Y[%] (Y>0) from the maximum value of the switching control signal from Wmax[%], adds 1 to the alarm count, and sets the duration tc to zero (step S9B).

[0065] On the other hand, if the result in step S8B is No, this flow returns to step S5. The cases in step S8B where the result is No include when it is determined that the maximum value Wmax[%] of the switching control signal is Winit[%], and when it is determined that the duration tc is less than the second predetermined period T2.

[0066] After step S9A or step S9B is executed, the compressor control unit 91 determines whether the alarm count is greater than a predetermined value (for example, 4 times) (step S10A).

[0067] If the answer in step S10A is Yes, the compressor control unit 91 outputs a serious fault signal to a notification unit (not shown) and notifies the user of the serious fault via the notification unit (step S11A). The notification unit may be a display unit (such as a monitor) capable of notifying the serious fault signal as text, an image, etc., a light source capable of notifying the serious fault signal as light, or a speaker capable of notifying the serious fault signal as sound. The display unit used as the notification unit may be an external display capable of receiving and displaying the serious fault signal via communication. The compressor control unit 91 may also be configured to output a serious fault signal when the maximum value Wmax of the switching control signal falls below a second predetermined percentage (for example, 40%) which is smaller than a first predetermined percentage described later.

[0068] After step S11A is executed, the compressor control unit 91 stops the main unit 10 and controls the opening / closing adjustment unit 60 so that the intake control valve 50 is fully closed (step S12). After step S12 is executed, this flow ends.

[0069] Furthermore, if the answer in step S10A is No, the compressor control unit 91 determines whether or not a minor fault signal has been issued (step S10B).

[0070] If the answer in step S10B is Yes, the compressor control unit 91 outputs a minor fault signal to a notification unit (not shown) and notifies the user of the minor fault via the notification unit (step S11B). After step S11B is executed, this flow returns to step S5. The compressor control unit 91 may also be configured to output a minor fault signal when the maximum value Wmax of the on / off control signal falls below a first predetermined percentage (for example, 85%).

[0071] Furthermore, if the answer in step S10B is No, this flow returns to step S5. One example of a case where the answer in step S10B is No is when a minor fault signal has already been issued.

[0072] The compressor 1 according to an embodiment of the present invention comprises a main unit 10, an air end 20 that compresses air by the rotational force of the main unit 10, an intake adjustment unit that adjusts the amount of air supplied to the air end 20, an oil chamber 30 in which the air compressed by the air end 20 is stored, a pressure sensor (discharge pressure sensor 83) that detects the internal pressure of the oil chamber 30, a rotational speed sensor 81 that detects the rotational speed of the main unit 10, an open / close control signal for controlling the intake adjustment unit, and a control unit that generates a rotational speed control signal for controlling the main unit 10. The open / close control signal sets the value at which the intake adjustment unit is fully closed to 0% and the value at which the intake adjustment unit is fully open to 100%. The control unit controls the main unit 10 and the intake adjustment unit based on the internal pressure detected by the pressure sensor. Furthermore, when the rotational speed detected by the rotational speed sensor 81 is less than the target rotational speed, if the rotational speed control signal is maintained at V% or higher for a first predetermined period T1, the control unit sets the maximum value of the open / close control signal to a value obtained by subtracting X% from the initial value. Therefore, the compressor 1 can continue operating while preventing sudden stalls of the main unit 10 in the event of minor malfunctions, etc., by shifting to an operating point where the power generated by the main unit 10 is sufficient to meet the power requirements at the air end 20.

[0073] The control unit reduces the maximum value of the opening / closing control signal by X%, and then, if the rotation speed control signal remains at or above W% during the second predetermined period T2, it repeatedly sets the maximum value of the opening / closing control signal to a value that is Y% less than the current value. Therefore, the compressor 1 can continue operating while more effectively preventing sudden stalls of the main unit 10 in the event of minor malfunctions.

[0074] The control unit sets the maximum value of the on / off control signal to a value obtained by subtracting Z% from the initial value, according to the settings when the compressor 1 is started. Therefore, when using alternative fuels, etc., the compressor 1 can continue to operate without requiring any modifications that would require specialized knowledge, while preventing sudden stalls of the main engine 10.

[0075] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified as appropriate without departing from the spirit of the invention. For example, the compressor control unit 91 may be configured to measure the duration tc as a cumulative value without resetting it in the first predetermined period T1 and the second predetermined period T2. In this case, the compressor control unit 91 compares and determines the duration tc with the cumulative value of the first predetermined period T1 and the second predetermined period T2.

[0076] In other words, if the duration tc during which the rotational speed control signal value is continuously maintained at V[%] or higher is 0 or greater and less than T1, the maximum value Wmax of the opening / closing control signal is set to Wmax=W[%]. Also, if the duration tc is T1+kT2 or greater and less than T1+(k+1)T2, the maximum value Wmax of the opening / closing control signal is set to Wmax=W-(X+kY)[%] (where k is a non-negative integer).

[0077] The multiplier k of Y at a given duration tc is equal to the largest integer less than or equal to the value obtained by subtracting the first predetermined period T1 from the duration tc and dividing it by the second predetermined period T2. For example, if tc = T1 + 2.5T2, k is calculated as follows: k = floor((tc - T1) / T2) =floor(2.5T2 / T2) =2 Here, floor(x) is the floor function and represents the largest integer less than or equal to x.

[0078] Furthermore, the compressor control unit 91 may be configured to perform a determination in steps S9A and S9B based on the cumulative value of the duration tc or the maximum opening degree of the intake adjustment unit, instead of the alarm count. Also, the intake adjustment unit is not limited to the intake adjustment valve 50 and the opening / closing adjustment unit 60 described above, but may be a solenoid valve or the like whose opening degree can be linearly controlled by an opening / closing control signal from the compressor control unit 91. [Explanation of symbols]

[0079] 1 Compressor 2a First air flow path 2b Second air flow path 2c Third air flow path 2d Fourth air flow path 2e Fifth air flow path 10 Main engine 20 Air End 30 Oil Chamber 40 Service Valves 50 Intake control valve (intake control section) 60 Opening / closing adjustment section (intake adjustment section) 71 Check valve 72 Orifice 73 Orifice 81 Rotation speed sensor 82 Control pressure sensor 83 Discharge pressure sensor (pressure sensor) 91 Compressor Control Unit (Control Unit) 92 Main engine control section (control section)

Claims

1. Main engine and An air end that compresses air using the rotational force of the main engine, An intake adjustment unit that adjusts the amount of air supplied to the air end, An oil chamber in which the air compressed by the air end is stored, A pressure sensor for detecting the internal pressure of the oil chamber, A rotation speed sensor for detecting the rotation speed of the main engine, A control unit that generates an open / close control signal for controlling the intake adjustment unit and a rotational speed control signal for controlling the main engine, Equipped with, The opening / closing control signal sets the value at which the intake adjustment unit is fully closed to 0% and the value at which the intake adjustment unit is fully open to 100%. The control unit, Based on the internal pressure detected by the pressure sensor, the main engine and the intake adjustment unit are controlled. When the rotational speed detected by the rotational speed sensor is less than the target rotational speed, and the rotational speed control signal remains at V% or higher for a first predetermined period, the maximum value of the opening / closing control signal is set to a value obtained by subtracting X% from the initial value. A compressor characterized by the following features.

2. The control unit, after reducing the maximum value of the opening / closing control signal by X%, repeatedly sets the maximum value of the opening / closing control signal to a value obtained by reducing the current value by Y% if the rotation speed control signal remains at V% or higher for a second predetermined period. The compressor according to feature 1.

3. The control unit sets the maximum value of the on / off control signal to a value obtained by subtracting Z% from the initial value, according to the settings when the compressor is started. The compressor according to claim 1 or 2, characterized in that it is as described above.

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