JP2013254899A - Cooling device and fluid pressure unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device capable of estimating the deterioration of the heat transmission performance which occurs when a thickness of a heat transmission silicone provided between a semiconductor element and a heat radiation fin is reduced.SOLUTION: A silicone performance deterioration estimation part 62 estimates the deterioration of the heat transmission performance of a silicone when a temperature of a heat radiation fin, which is detected by a heat radiation fin temperature sensor, becomes lower than a first reference value determined according to a heat value of a power module.

Description

  The present invention relates to a cooling device that cools a heating element such as a power module of an inverter, and a fluid pressure unit including the cooling device.

  Conventionally, there is a cooling device disclosed in Japanese Patent Application Laid-Open No. 2004-200428 (Patent Document 1). This cooling device has a heat radiating fin thermally connected to the semiconductor element, and releases the heat generated from the semiconductor element to the outside through the heat radiating fin to cool the semiconductor element.

JP 2004-200428 A

  By the way, when the said conventional cooling device was used, the problem that the heat | fever of the said semiconductor element became difficult to be transmitted to the said radiation fin was discovered.

  This is because silicon is disposed between the semiconductor element and the radiating fin, and the thickness of the silicon is unclear in the surface direction over time although the reason is unknown.

  That is, the contact area of the silicon with the semiconductor element and the contact area of the silicon with the heat radiation fin are reduced, and the heat transfer performance from the semiconductor element to the heat radiation fin through the silicon is lowered. In short, the heat transfer performance of the silicon is reduced.

  Conventionally, this decrease in the heat transfer performance of silicon has not been recognized, so that the semiconductor element cannot sufficiently dissipate heat when the thickness of the silicon is reduced.

  Accordingly, an object of the present invention is to provide a cooling device and a liquid pressure unit capable of estimating a decrease in the heat transfer performance of silicon.

In order to solve the above problems, the cooling device of the present invention is:
A device for cooling a heating element,
Radiating fins thermally connected to the heating element;
Silicon disposed on a portion of the heat dissipating fin connected to the heating element;
A radiation fin temperature sensor for detecting the temperature of the radiation fin;
Silicon performance for estimating a decrease in heat transfer performance of the silicon when the temperature of the heat radiating fin detected by the heat radiating fin temperature sensor falls below a first reference value determined according to the amount of heat generated by the heating element. And a decrease estimation unit.

  According to the cooling device of the present invention, the silicon performance deterioration estimation unit, when the temperature of the radiation fin detected by the radiation fin temperature sensor is below a first reference value determined according to the amount of heat generated by the heating element. Estimate the decrease in heat transfer performance of silicon.

  Thus, the user can recognize a decrease in the silicon thickness that causes a decrease in the heat transfer performance of silicon, and can sufficiently dissipate heat from the heating element by exchanging or supplementing silicon.

  Moreover, in the cooling device of one embodiment, when the temperature of the radiating fin detected by the radiating fin temperature sensor exceeds a second reference value determined according to the amount of heat generated by the heating element, the radiating fin is disposed. A heat dissipating fin performance deterioration estimation unit for estimating a decrease in the cooling performance of the motor is provided.

  According to the cooling device of this embodiment, the radiating fin performance deterioration estimation unit obtains the second reference value in which the temperature of the radiating fin detected by the radiating fin temperature sensor is determined according to the amount of heat generated by the heating element. When it exceeds, the fall of the cooling performance of a radiation fin will be estimated.

  As a result, the user can recognize the adhesion of dust to the radiating fin and the obstruction of the air flow to the radiating fin, which cause the cooling performance of the radiating fin to be reduced. Can be sufficiently dissipated.

Moreover, in the cooling device of one embodiment,
An ambient temperature sensor for detecting the ambient temperature;
Based on the ambient temperature detected by the ambient temperature sensor and the load of the heating element, a radiation fin estimated temperature acquisition unit for obtaining a radiation fin estimated temperature that is a normal temperature of the radiation fin,
The silicon performance degradation estimation unit uses the value obtained by subtracting a set value from the heat radiation fin estimated temperature obtained by the heat radiation fin estimated temperature acquisition unit as the first reference value, and is detected by the heat radiation fin temperature sensor. Compared to the temperature of the radiating fin,
The heat radiating fin performance deterioration estimation unit is detected by the heat radiating fin temperature sensor using a value obtained by adding a set value to the heat radiating fin estimated temperature obtained by the heat radiating fin estimated temperature acquisition unit as the second reference value. It compares with the temperature of the said radiation fin.

  Here, the “heating element load” is a load such as a current applied to the heating element, and the heat generation amount of the heating element increases as the load increases.

  According to the cooling device of this embodiment, the heat radiating fin estimated temperature acquisition unit obtains the heat radiating fin estimated temperature, and the silicon performance lowering estimation unit reduces the heat transfer performance of silicon based on the heat radiating fin estimated temperature. The radiating fin performance deterioration estimation unit estimates a decrease in cooling performance of the radiating fin based on the radiating fin estimated temperature.

  As a result, it is possible to accurately estimate the silicon performance degradation and the heat radiation fin performance degradation.

In the fluid pressure unit of one embodiment,
A fluid pressure pump for supplying fluid in a fluid tank to a fluid pressure actuator;
A variable speed motor for driving the fluid pressure pump;
A radiator for cooling the fluid in the fluid tank;
Flow rate control for controlling the rotational speed of the variable speed motor to set the discharge flow rate of the fluid pressure pump to a set value, and control of the rotational speed of the variable speed motor to set the discharge pressure of the fluid pressure pump to a set value A rotational speed control means for switching pressure control;
Including the cooling device,
The rotation speed control means includes an inverter that controls the rotation speed of the variable speed motor by passing a current through the variable speed motor;
The cooling device cools the inverter as the heating element.

  According to the fluid pressure unit of this embodiment, since the cooling device is provided, the cooling device can sufficiently dissipate heat from the inverter.

  According to the cooling device of the present invention, the silicon performance deterioration estimation unit, when the temperature of the radiation fin detected by the radiation fin temperature sensor is below a first reference value determined according to the amount of heat generated by the heating element. Estimate the decrease in heat transfer performance of silicon. Thereby, the reduction | decrease of the silicon thickness which causes the fall of the heat transfer performance of silicon | silicone can be recognized, and heat dissipation of a heat generating body can fully be performed.

  According to the fluid pressure unit of this embodiment, since the cooling device is provided, the cooling device can sufficiently dissipate heat from the inverter.

It is a circuit diagram which shows the hydraulic unit of an example of the fluid pressure unit of this invention. It is a discharge pressure-discharge flow rate characteristic view of a hydraulic pump. It is a simplified diagram showing a cooling device of the present invention. It is a block diagram which shows the performance estimation part of a cooling device. It is a graph which shows the relationship between the radiation fin temperature and motor current at the time of continuing operation | movement at the time of pressure holding. It is a graph which shows the relationship between a radiation fin raise temperature and a motor current. It is a flow which shows operation | movement of a performance estimation part.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 is a circuit diagram showing a hydraulic unit according to an embodiment of the present invention. The hydraulic unit 1 is an example of a fluid pressure unit of the present invention, and is used for machine tools such as a lathe, a polishing machine, a surface finishing machine, a shaving machine, and a machining center.

  Although not shown, the machine tool has a plurality of hydraulic actuators for fixing a work and a tool, such as a tailstock clamp, a tool post clamp, and a chuck, and these hydraulic actuators are driven by the hydraulic unit 1. The

  The hydraulic unit 1 includes a hydraulic circuit 10 and a control unit 30 for controlling the hydraulic circuit 10.

  The hydraulic circuit 10 includes an oil tank 11, a hydraulic pump 13, a pump motor 14 that drives the hydraulic pump 13, a throttle passage 21, and a radiator 23.

  The hydraulic pump 13 is an example of a fluid pressure pump, and sucks hydraulic oil in the oil tank 11 which is an example of a fluid tank and discharges the hydraulic oil to a hydraulic actuator. The hydraulic pump 13 is, for example, a piston pump, and is a fixed displacement pump.

  The pump motor 14 is a variable speed motor that is connected to the hydraulic pump 13 and drives the hydraulic pump 13. A pulse generator 15 that outputs a pulse signal corresponding to the rotational speed of the pump motor 14 is connected to the pump motor 14.

  An oil filter 12 is provided on the suction side of the hydraulic pump 13. A relief valve 16 is provided in the discharge pipe 18 of the hydraulic pump 13 so that the discharge pressure of the hydraulic pump 13 does not exceed a predetermined pressure.

  The discharge pipe 18 of the hydraulic pump 13 is provided with a pressure sensor 17 that detects the discharge pressure of the hydraulic pump 13. The discharge pipe 18 of the hydraulic pump 13 is connected to a hydraulic actuator on the machine tool side via a direction switching valve (not shown).

  The throttle passage 21 is connected to the oil tank 11 and the discharge pipe 18 of the hydraulic pump 13. A variable throttle valve 22 is provided in the throttle passage 21. The throttle passage 21 is configured such that a part of the hydraulic oil discharged from the hydraulic pump 13 always returns to the oil tank 11 without flowing to the machine tool side. The return amount to the oil tank 11 is adjusted by the variable throttle valve 22.

  By providing the throttle passage 21, it is possible to reliably avoid operating the hydraulic pump 13 in the low rotation region. That is, since a part of the hydraulic oil discharged from the hydraulic pump 13 flows into the throttle passage 21, the discharge flow rate of the hydraulic pump 13 becomes larger than the flow rate required for the actuator of the machine tool. If it does so, the hydraulic pump 13 will be drive | operated in a comparatively high rotation area | region. As a result, it is possible to avoid the hydraulic pump 13 being operated at a low speed, and pressure control / flow rate control can be performed stably.

  The radiator 23 is provided on the downstream side of the variable throttle valve 22 in the throttle passage 21. The radiator 23 includes a radiator body 231, a radiator fan 232, and a fan motor 233.

  The radiator main body 231 is connected to the throttle passage 21. The radiator fan 232 cools the hydraulic oil that passes through the radiator body 231. The fan motor 233 drives the radiator fan 232.

  Thus, the radiator 23 cools the hydraulic oil in the oil tank 11 and suppresses the temperature rise of the hydraulic oil.

  The hydraulic pump 13 is provided with a drain passage 25. The drain passage 25 is connected between the variable throttle valve 22 and the radiator 23 in the throttle passage 21. In the drain passage 25, the hydraulic oil leaked in the hydraulic pump 13 flows into the throttle passage 21.

  The control unit 30 includes a PQ control unit 31, a speed control unit 32, an inverter 33, a speed detection unit 34, and a cooling device 50.

  The discharge pressure of the hydraulic pump 13 is input from the pressure sensor 17 to the PQ control unit 31. The PQ control unit 31 outputs a speed command based on the input discharge pressure and the discharge pressure-discharge flow rate characteristic (hereinafter referred to as PQ characteristic) shown in FIG.

  The speed detector 34 receives a pulse signal from the pulse generator 15 and measures the interval between the pulse signals to detect the rotational speed of the pump motor 14 as the current speed.

  The speed controller 32 receives a speed command from the PQ controller 31 and a current speed from the speed detector 34. Then, the speed control unit 32 performs a speed control calculation using the speed command and the current speed, and outputs a current command.

  The inverter 33 receives a current command from the speed control unit 32, and controls the rotational speed of the pump motor 14 by flowing a current to the pump motor 14 based on the current command.

  The PQ control unit 31, the speed control unit 32, and the inverter 33 constitute rotation speed control means. The rotational speed control means switches between flow control and pressure control of the hydraulic pump 13 based on the PQ characteristic shown in FIG.

  In the flow rate control, the rotation speed (rotational speed) of the pump motor 14 is controlled so that the discharge flow rate of the hydraulic pump 13 becomes the flow rate set value Qa. That is, when controlling the flow rate at point A in FIG. 2, for example, a hydraulic cylinder as a hydraulic actuator performs an expansion operation or a contraction operation at a constant speed, and the workpiece or tool moves to a predetermined position. At that time, the discharge pressure of the hydraulic pump 13 becomes a relatively low value.

  In the pressure control, the rotation speed (rotational speed) of the pump motor 14 is controlled so that the discharge pressure of the hydraulic pump 13 becomes a set value (dead head pressure) Pa. That is, at the time of pressure control at point B in FIG. 2, for example, the hydraulic cylinder does not expand and contract, and the workpiece and tool are clamped and held with a predetermined force. In this state, the discharge flow rate of the hydraulic pump 13 is almost zero and is in a dead head state.

  As shown in FIG. 3, the cooling device 50 is attached to the power module 331 of the inverter 33 and cools the power module 331. The power module 331 is an example of a heating element of the present invention.

  The cooling device 50 includes a radiating fin 51, silicon 52, a radiating fin temperature sensor 53, an ambient temperature sensor 54, a cooling fan 55, and a performance estimation unit 60.

  The heat radiating fins 51 are thermally connected to the power module 331. That is, the heat generated from the power module 331 is released to the outside through the radiation fins 51.

  The silicon 52 is a heat conductive adhesive and is disposed on a portion of the heat radiation fin 51 connected to the power module 331. The silicon 52 bonds the heat radiation fin 51 and the power module 331.

  The radiation fin temperature sensor 53 is attached to the radiation fin 51 and detects the temperature of the radiation fin 51. The ambient temperature sensor 54 is disposed on the substrate 332 of the inverter 33 so as to be separated from the radiation fins 51 and detects the temperature around the radiation fins 51.

  The cooling fan 55 sends air to the radiating fins 51 to release the heat of the radiating fins 51.

  As shown in FIGS. 3 and 4, the performance estimation unit 60 includes a radiation fin estimated temperature acquisition unit 61, a silicon performance degradation estimation unit 62, and a radiation fin performance degradation estimation unit 63.

  The heat radiation fin estimated temperature acquisition unit 61 obtains a heat radiation fin estimated temperature, which is a normal temperature of the heat radiation fin 51, based on the ambient temperature detected by the ambient temperature sensor 54 and the load of the power module 331. .

  Here, the “load of the power module 331” is a load of current applied to the power module 331, that is, this current is a current for driving the pump motor 14, and if this load increases, the power module The amount of heat generated by 331 increases.

  At this time, the heat radiating fin estimated temperature acquisition unit 61 estimates an abnormality based on previously obtained reference data. This reference data is obtained in advance by experiments.

  That is, the pressure holding state is continued, and the operating time, the ambient temperature, the motor current value proportional to the motor rotation speed, and the radiation fin temperature are measured with the actual machine. At that time, the motor current average value is measured while being changed stepwise from 1A to 10A, and a database is created as shown in FIG.

  FIG. 5 shows the relationship between the radiating fin temperature and the motor current (average) value when the pressure keeping operation is continued at each pressure while changing the pressure at the ambient temperature of 25 ° C.

  Subsequently, a database is created as shown in FIG. 6 using the elapsed time from the start of operation and the radiating fin rising temperature ΔT as parameters. In FIG. 6, let t be the elapsed time from the start of operation. The operation time t is a sufficiently long time with respect to the operation cycle in which the temperature rise of the radiating fin is stabilized.

  Then, the radiating fin estimated temperature acquisition unit 61 inputs the operating time t and the motor current to the graph of FIG. 6 to obtain the radiating fin rising temperature ΔT, and adds the ambient temperature to the radiating fin rising temperature ΔT. The estimated temperature of the radiating fin is obtained.

  The database may be programmed in the form of a memory or an approximate expression and executed by the microcomputer of the cooling device 50, or may be executed using a personal computer or the like outside the cooling device 50.

  The silicon performance degradation estimation unit 62 uses a first reference value in which the temperature of the radiation fin 51 detected by the radiation fin temperature sensor 53 is determined according to the amount of heat generated by the power module 331 (that is, the motor current value). Below this, a decrease in the heat transfer performance of silicon is estimated.

  More specifically, the silicon performance degradation estimating unit 62 uses the value obtained by subtracting a set value from the estimated heat radiation fin temperature obtained by the heat radiation fin estimated temperature obtaining unit 61 as the first reference value, and the heat radiation fin temperature sensor. Compared with the temperature of the radiation fin 51 detected by 53.

  The heat radiating fin performance deterioration estimation unit 63 has a second reference value in which the temperature of the heat radiating fin 51 detected by the heat radiating fin temperature sensor 53 is determined according to the amount of heat generated by the power module 331 (that is, the motor current value). Is exceeded, a decrease in the cooling performance of the radiating fins 51 is estimated.

  More specifically, the radiating fin performance degradation estimating unit 63 uses the value obtained by adding a set value to the radiating fin estimated temperature obtained by the radiating fin estimated temperature acquiring unit 61 as the second radiating fin temperature. The temperature is compared with the temperature of the radiating fin 51 detected by the sensor 53.

  The performance estimation unit 60 performs the operation of FIG. As shown in FIG. 7, the operating time t and the motor current I are input to the graph Ft of FIG. 6 to obtain the radiating fin rising temperature ΔT [° C.], and the ambient temperature T is added to the radiating fin rising temperature ΔT. Then, the estimated heat radiation fin temperature Tef [° C.] is obtained (step S1). The heat radiating fin estimated temperature acquisition unit 61 includes step S1.

  Then, it is determined whether or not the value obtained by subtracting the heat radiation fin estimated temperature Tef from the heat radiation fin temperature Tf [° C.] detected by the heat radiation fin temperature sensor 53 exceeds the temperature rise maximum value K1 [° C.] (step S2). .

  If the temperature rise maximum value K1 [° C.] is exceeded (step S2), it is estimated that the cooling performance of the radiating fin is lowered (step S5). The heat radiating fin performance deterioration estimation unit 63 includes step S2 and step S5.

  On the other hand, if the temperature rise maximum value K1 [° C.] is not exceeded (step S2), it is determined whether or not the value obtained by subtracting the heat radiation fin temperature Tf from the heat radiation fin estimated temperature Tef exceeds the temperature rise minimum value K2 [° C.]. (Step S3). If the temperature rise minimum value K2 [° C.] is exceeded, it is estimated that the heat transfer property of silicon is lowered (step S4). The silicon performance degradation estimation unit 62 is composed of step S3 and step S4.

  According to the cooling device 50 having the above-described configuration, the silicon performance deterioration estimation unit 62 estimates a decrease in the heat transfer performance of the silicon 52. As a result, the user can recognize the decrease in the thickness of the silicon 52 that causes the heat transfer performance of the silicon 52 to be reduced, and the power module 331 can sufficiently dissipate heat by replacing or supplementing the silicon 52. Can do.

  Further, the radiating fin performance deterioration estimation unit 63 estimates a decrease in cooling performance of the radiating fin 51. Thus, the user can recognize the adhesion of dust to the radiation fins 51 and the obstruction of the air flow to the radiation fins 51 that cause the cooling performance of the radiation fins 51 to be reduced, and clean the radiation fins 51. Thus, the power module 331 can sufficiently dissipate heat.

  Moreover, the said heat radiation fin estimated temperature acquisition part 61 calculates | requires heat radiation fin estimated temperature, and the said silicon performance fall estimation part 62 estimates the fall of the heat transfer performance of the silicon | silicone 52 based on this heat radiation fin estimated temperature, The above-mentioned The radiating fin performance decrease estimation unit 63 estimates a decrease in the cooling performance of the radiating fin 51 based on the estimated radiating fin temperature. Thereby, it is possible to accurately estimate the performance degradation of the silicon 52 and the performance degradation of the heat radiation fin 51.

  Moreover, according to the hydraulic unit 1 having the above-described configuration, since the cooling device 50 is provided, the cooling device 50 can sufficiently dissipate heat from the inverter 33.

  In addition, this invention is not limited to the above-mentioned embodiment.

  In the said embodiment, although the radiation fin performance fall estimation part 63 was provided, you may abbreviate | omit this.

  In the above embodiment, the cooling device 50 is applied to a hydraulic unit. However, the cooling device 50 may be applied to a device other than a machine tool or a fluid pressure unit using a fluid other than hydraulic oil.

  In the above embodiment, the cooling device 50 is applied to a hydraulic unit. However, the cooling device 50 may be applied to any device as long as it has a heating element that generates heat, such as a semiconductor element.

1 Hydraulic unit (fluid pressure unit)
10 Hydraulic circuit 11 Oil tank (fluid tank)
12 Oil filter 13 Hydraulic pump (fluid pressure pump)
14 Pump motor (variable speed motor)
16 Relief valve 17 Pressure sensor 23 Radiator 30 Control unit 31 PQ control unit (rotational speed control means)
32 Speed controller (rotational speed control means)
33 Inverter (rotational speed control means)
331 Power module (heating element)
DESCRIPTION OF SYMBOLS 50 Cooling device 51 Radiation fin 52 Silicon 53 Radiation fin temperature sensor 54 Ambient temperature sensor 60 Performance estimation part 61 Radiation fin estimated temperature acquisition part 62 Silicon performance fall estimation part 63 Radiation fin performance fall estimation part

Claims (4)

A device for cooling a heating element,
A radiation fin (51) thermally connected to the heating element;
Silicon (52) disposed on a portion of the heat dissipating fin (51) connected to the heating element;
A radiation fin temperature sensor (53) for detecting the temperature of the radiation fin (51);
When the temperature of the radiating fin (51) detected by the radiating fin temperature sensor (53) falls below a first reference value determined according to the amount of heat generated by the heating element, the heat of the silicon (52) A cooling device comprising: a silicon performance deterioration estimation unit (62) for estimating a decrease in transmission performance. The cooling device according to claim 1, wherein
When the temperature of the radiating fin (51) detected by the radiating fin temperature sensor (53) exceeds a second reference value determined according to the amount of heat generated by the heating element, the radiating fin (51) A cooling device comprising a radiating fin performance deterioration estimation unit (63) for estimating a decrease in cooling performance. The cooling device according to claim 2, wherein
An ambient temperature sensor (54) for detecting the ambient temperature;
Based on the ambient temperature detected by the ambient temperature sensor (54) and the load on the heating element, a radiation fin estimated temperature acquisition unit for obtaining a radiation fin estimated temperature that is a normal temperature of the radiation fin (51) ( 61)
The silicon performance degradation estimation unit (62) uses the value obtained by subtracting a set value from the heat radiation fin estimated temperature obtained by the heat radiation fin estimated temperature acquisition unit (61) as the first reference value, and the heat radiation fin temperature. Compared to the temperature of the radiating fin (51) detected by the sensor (53),
The heat radiating fin performance deterioration estimation unit (63) uses the value obtained by adding a set value to the heat radiating fin estimated temperature obtained by the heat radiating fin estimated temperature acquisition unit (61) as the second reference value. The cooling device characterized by comparing with the temperature of the radiation fin (51) detected by the temperature sensor (53). A fluid pressure pump (13) for supplying fluid in the fluid tank (11) to a fluid pressure actuator;
A variable speed motor (14) for driving the fluid pressure pump (13);
A radiator (23) for cooling the fluid in the fluid tank (11);
A flow rate control for controlling the rotational speed of the variable speed motor (14) to set the discharge flow rate of the fluid pressure pump (13) to a set value, and a rotational speed of the variable speed motor (14) for controlling the fluid pressure. A rotation speed control means (31, 32, 33) for switching pressure control for setting the discharge pressure of the pump (13) to a set value;
The cooling device (50) according to any one of claims 1 to 3,
The rotation speed control means (31, 32, 33) includes an inverter (33) that controls the rotation speed of the variable speed motor (14) by supplying a current to the variable speed motor (14).
The fluid pressure unit, wherein the cooling device (50) cools the inverter (33) as the heating element.

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