Traction motor bearing internal temperature inversion system and method based on external temperature measuring point

Abstract

The application provides a kind of traction motor bearing internal temperature inversion system and method based on external temperature measuring point, it is related to equipment state monitoring technical field.System includes temperature acquisition module, operating condition parameter acquisition module, temperature inversion model module and result output module;Temperature acquisition module acquires the temperature of multiple external temperature measuring points on the outer surface of motor, operating condition parameter acquisition module acquires motor operating condition parameters, temperature inversion model module fuses two types of data to calculate bearing internal target position inversion temperature, and result output module completes result output.The application establishes the mapping relationship between external measurable information and internal temperature by multi-source data fusion, combined with circumferential multi-measuring point layout, consistency check weighted fusion and prediction deviation adaptive correction, improves the accuracy, reliability and anti-interference ability of inversion temperature, realizes non-invasive temperature inversion, and provides easy engineering implementation technical support for traction motor bearing thermal state evaluation, fault early warning and life prediction.

Description

Technical Field

[0001] This invention relates to the field of equipment condition monitoring technology, and more specifically, to a system and method for inverting the internal temperature of a traction motor bearing based on an external temperature measurement point. Background Technology

[0002] As a critical component, the internal operating temperature of high-speed railway traction motor bearings is a crucial indicator reflecting their lubrication status, wear degree, and operational risks. Accurately obtaining the internal temperature of the bearing is essential for condition monitoring and safety assessment. Current technologies typically employ temperature sensors directly placed on the outer surface of the bearing ring or bearing housing to measure bearing temperature. However, the heat generated inside the bearing and conducted to the outer surface involves a complex heat transfer path and is affected by operating conditions, resulting in a significant difference between the temperature measured on the outer surface and the actual temperature of critical internal components, failing to accurately reflect the internal thermal state. Directly placing sensors inside the bearing requires invasive modifications to the bearing structure, which is not only difficult and costly but may also damage the original structure and stress state of the bearing, making it impractical for real-world engineering applications. Therefore, how to accurately deduce the temperature of critical internal components of the bearing based on externally available temperature information without intruding into the internal structure has become a pressing technical problem in the field of traction motor bearing condition monitoring. Summary of the Invention

[0003] The purpose of this invention is to provide a system and method for inverting the internal temperature of a traction motor bearing based on an external temperature measurement point. It addresses the shortcomings of existing technologies and solves the problems mentioned in the background.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A traction motor bearing internal temperature inversion system based on external temperature measurement points includes:

[0006] The temperature acquisition module is used to collect temperature data from multiple external temperature measuring points set on the outer surface of the traction motor.

[0007] The operating condition parameter acquisition module is used to collect the operating condition parameters of the traction motor.

[0008] The temperature inversion model module is connected to the temperature acquisition module and the operating condition parameter acquisition module. It is used to calculate the inversion temperature of the target position inside the bearing of the traction motor based on temperature data and operating condition parameters.

[0009] The results output module is connected to the temperature inversion model module and is used to output the inversion temperature.

[0010] Preferably, multiple external temperature measuring points are evenly distributed along the circumference of the bearing housing.

[0011] Furthermore, the temperature acquisition module includes an external temperature sensor, which is a platinum resistance thermometer.

[0012] Preferably, the temperature acquisition module further includes an installation structure, which includes a press-fit component and a seal. The press-fit component is used to press and fix the temperature acquisition module into the temperature measuring mounting hole of the traction motor, and the seal is disposed between the temperature acquisition module and the inner wall of the temperature measuring hole.

[0013] Furthermore, the operating condition parameter acquisition module is used to acquire at least one of the following: traction motor speed, bearing load, and ambient temperature.

[0014] Preferably, the operating condition parameter acquisition module further includes a data preprocessing unit, which is used to filter the acquired operating condition parameters, including Kalman filtering and moving average filtering.

[0015] Preferably, the temperature inversion model module includes a consistency verification unit, which is used to verify the temperature data of multiple external temperature measurement points and remove abnormal data. The consistency verification unit determines abnormal data based on the 3σ criterion and the temperature difference verification between adjacent measurement points.

[0016] Preferably, the temperature inversion model module further includes a weighted fusion unit, which is used to perform a weighted average of the temperature data of multiple external temperature measurement points verified by the consistency verification unit to obtain the equivalent external temperature;

[0017] In the weighted fusion unit, the weight of each measuring point temperature is determined based on the heat transfer path characteristics of the measuring point, the installation distance, and the experimental calibration results;

[0018] The temperature inversion model module is also configured to adaptively correct the inverted temperature based on the deviation between the predicted and actual measured values ​​at external temperature measurement points.

[0019] A method for inverting the internal temperature of a traction motor bearing based on an external temperature measurement point includes the following steps:

[0020] S1. Acquire temperature data from various external temperature measurement points at the same time, perform consistency verification and weighted fusion on the acquired temperature data, and obtain the equivalent external temperature;

[0021] S2. Collect the operating parameters of the traction motor;

[0022] S3. Based on the equivalent external temperature collected in step S1 and the operating condition parameters collected in step S2, the inversion temperature of the target position inside the bearing of the traction motor is calculated using the temperature inversion model.

[0023] S4. Adaptively correct the inverted temperature based on the deviation between the predicted value and the actual measured value of the external temperature measuring point;

[0024] S5. Output inversion temperature.

[0025] In step S1, the weighted fusion calculation determines the weights based on the heat transfer path characteristics of the measuring points, the installation distance, and the experimental calibration results, and obtains the equivalent external temperature through weighted averaging:

[0026]

[0027] Weight The value is determined by the heat transfer path contribution, installation distance, and calibration results, and is in the form of... ;

[0028] in:

[0029] for t The equivalent temperature at any given moment. for t Time of the first i Temperature values ​​at each measuring point The total number of samples, d i For the first i The equivalent heat transfer path distance from the measuring point to the target area of ​​the bearing. p The distance decay exponent; These are calibration coefficients; This is the normalization constant.

[0030] The present invention has at least the following advantages or beneficial effects:

[0031] This invention collects temperature data from the outer surface of the traction motor and combines it with its operating parameters to calculate the temperature at a target location inside the bearing using a temperature inversion model. Since the temperature at the external measuring point is a comprehensive reflection of the bearing's internal thermal state after heat transfer, and the operating parameters directly affect the bearing's heating and cooling processes, inputting both into the model for fusion processing allows for a more accurate establishment of the mapping relationship between externally measurable information and the actual internal temperature, thus achieving non-invasive inversion of the bearing's internal temperature. Compared to existing technologies that only measure temperature at a single external point, this invention significantly improves the accuracy and reliability of the inverted temperature by fusing data from multiple external measuring points and considering the influence of operating conditions. In particular, by setting multiple external temperature measuring points evenly distributed along the circumference of the bearing housing and combining consistency verification and weighted fusion processing, the thermal distribution characteristics along the bearing's circumference can be effectively covered, and abnormal data caused by local interference or sensor malfunctions can be eliminated, enhancing the system's resistance to external environmental disturbances and local anomalies. Simultaneously, by adaptively correcting the inverted temperature based on prediction bias, the model output can be continuously optimized, further improving the long-term accuracy and stability of the inversion results. This invention ultimately provides an accurate, reliable, and easily implemented technical foundation for thermal condition assessment, fault early warning, and life prediction of traction motor bearings. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic flowchart of the method for inverting the internal temperature of a traction motor bearing based on an external temperature measurement point, provided by the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] High-speed railway traction motor bearings operate under high-speed, heavy-load, and temperature-variable environments for extended periods, and their internal temperature directly affects lubrication performance and component lifespan. However, due to the enclosed structure of the bearings, directly measuring their internal temperature is extremely difficult. This invention provides a non-invasive solution that collects temperature data from measurable points on the outside of the motor, combines this data with operating conditions, and uses model inversion technology to calculate the temperature at a target location inside the bearing, thereby achieving accurate assessment and early warning of the bearing's thermal state.

[0036] This invention provides a traction motor bearing internal temperature inversion system based on external temperature measurement points. The system includes a temperature acquisition module, an operating condition parameter acquisition module, a temperature inversion model module, and a result output module.

[0037] The temperature acquisition module collects temperature data from multiple external temperature measuring points located on the outer surface of the traction motor. These external temperature measuring points are preferably located near the bearing mounting location to improve the sensitivity of temperature information to the internal thermal state of the bearing. The temperature acquisition module is press-fitted directly into the pre-drilled temperature measuring hole in the motor housing using an interference fit to ensure tight contact between the probe and the housing, reduce contact thermal resistance, and improve heat transfer efficiency. The temperature acquisition module body adopts a metal encapsulation or high-strength plastic encapsulation structure. The temperature probe of the acquisition module is designed as a cylindrical structure matching the temperature measuring hole, housing an external temperature sensor and signal processing unit. The encapsulation housing has pre-drilled mounting and positioning structures (stepped surface, threaded hole) to facilitate mating with the motor housing and fixed components. The connection points between the sensing element and the module body lead wires are treated with vulcanized sealant to form a root seal, preventing water and dust from seeping into the module and causing circuit failure. The external temperature sensor uses a PT100 platinum resistance thermometer, with a measurement range of -40℃ to +200℃ and an extreme temperature resistance of -50℃ to +250℃. The measurement accuracy is as follows: error ≤ ±(0.15℃ + 0.002|t|) in the -200℃ to 0℃ range and error ≤ ±(0.1℃ + 0.0017|t|) in the 0℃ to 200℃ range (t is the measured temperature value); response time ≤ 1s.

[0038] The temperature acquisition module also includes an installation structure, which comprises a press-fit component and a seal. The press-fit component is a metal pressure plate with an arc-shaped design that conforms to the shape of the module body, increasing the contact area and preventing excessive local stress that could damage the module. The press-fit component is mounted on the housing with screws, used to press and fix the temperature acquisition module into the temperature measurement mounting hole of the traction motor. The seal is located between the temperature probe of the acquisition module and the inner wall of the temperature measurement hole. The seals (O-rings, silicone sealing plugs) are made of wide-temperature-range materials (-40℃~+200℃), suitable for alternating high and low temperature conditions, and free from hardening, cracking, and aging issues.

[0039] The lead wire adopts a temperature- and oil-resistant double-shielded cable (PUR / CSM sheath, temperature resistance -40℃~+125℃), with a silver-plated copper wire core and an outer layer of tin-plated copper wire braided mesh + aluminum foil shielding, which takes into account wear resistance, corrosion resistance and electromagnetic interference resistance. The lead wire root is equipped with an integrated rubber protective sleeve (stress relief structure), which is fixed and sealed with a rubber pressure cap to prevent vibration breakage and pulling damage. The external connection adopts M16 / M20 specification rail transit special aviation plug, with the pin seat fixed to the motor housing, and with the sealing component and cable sealing joint, the protection level reaches IP67 / IP68. The aviation plug adopts an anti-loosening locking structure and an anti-misinsertion design, and the two ends of the shielding layer are reliably grounded to form a closed loop, which meets the EN 50121-3-2 electromagnetic compatibility standard.

[0040] The cabling section is protected by corrugated pipe and fixed at both ends with connectors to prevent scratches and squeezing; the cable is fixed with clamps / cable ties with rubber pads, with a spacing of ≤150mm, to buffer vibration and avoid damage to the sheath; the cabling avoids high-speed moving parts and high-voltage cables, and crosses perpendicularly when necessary to reduce interference and collision risks; the cable is reserved with 5%~10% expansion and contraction allowance to compensate for thermal expansion and contraction and vibration displacement, and to prevent pulling and breaking.

[0041] Multiple external temperature measuring points are evenly distributed along the circumference of the bearing housing. In this embodiment, there are 7 measuring points (for a single traction motor), including 3 on the drive end bearing housing, 3 on the non-drive end bearing housing, and 1 auxiliary measuring point on the stator housing. The 3 measuring points on the drive end bearing housing are evenly arranged along the circumference of the outer surface of the bearing housing, with an angle of 120° between adjacent measuring points. The 3 measuring points on the non-drive end bearing housing are also evenly arranged along the circumference, with an angle of 120° between adjacent measuring points, to cover the circumferential heat distribution of the bearing. The measuring points on the drive end and the non-drive end are located in different axial regions near the inner ring side and near the outer ring / end cover side of the bearing, respectively. The distance between the two axial regions is 50mm to 80mm, and the axial distance between the inner ring side region and the outer ring side region is ≥50mm, in order to avoid the influence of local heat dissipation blind spots and enhance the temperature gradient information.

[0042] The core data acquisition frequency is 10Hz~20Hz (normal operating conditions), and can be switched to 20Hz~50Hz (high-frequency acquisition mode) during the fault warning stage. The acquisition frequency is matched with the rate of change of the traction motor operating conditions. When the motor speed change rate is ≤50r / min·s, 10Hz acquisition is used. When the speed change rate is >50r / min·s or the load fluctuation amplitude is >10% of the rated load, it is automatically increased to 20Hz~50Hz to ensure the capture of transient temperature changes under dynamic operating conditions. The acquisition delay is ≤100ms (from temperature change to data upload completion).

[0043] The operating condition parameter acquisition module is used to collect the operating condition parameters of the traction motor. Specifically, it collects at least one of the following: traction motor speed, bearing load, and ambient temperature.

[0044] Traction motor speed: Acquired using a photoelectric encoder (incremental type, 1024 lines resolution), installed on the non-drive end of the motor shaft. It converts the detected shaft speed pulse signal into a speed value. The acquisition principle is pulse counting method (the number of pulses per unit time is converted into speed). The measurement range is 0~5000 r / min (suitable for high-speed train traction motors), the measurement accuracy is ±0.1%FS (full scale), and the resolution is 1 r / min.

[0045] Bearing load: The load is collected using a strain gauge load sensor (attached to the bearing housing support). The load value is converted by detecting the deformation of the bearing housing under force. The acquisition principle is amplification and conversion of strain gauge Wheatstone bridge signal; the measurement range is 0~200kN (single bearing), the measurement accuracy is ±1%FS, and the resolution is 0.1kN.

[0046] Ambient temperature: A waterproof NTC thermistor (accuracy ±0.5℃) is used for data acquisition, installed in a non-heat-dissipating area outside the motor (≥200mm from the motor housing). The acquisition principle is based on the thermistor's resistance changing with temperature. Measurement range: -40℃ to +80℃, measurement accuracy: ±0.5℃, resolution: 0.1℃.

[0047] The operating condition parameter acquisition module also includes a data preprocessing unit, which is used to filter the acquired operating condition parameters. The filtering process includes Kalman filtering and moving average filtering.

[0048] Kalman filtering: The state equation is X(k) = A·X(k-1) + B·u(k-1) + w(k-1), and the observation equation is Z(k) = H·X(k) + v(k), where the process noise w(k) variance Q = 0.01 and the observation noise v(k) variance R = 0.1. It is used to suppress random electromagnetic interference and sensor noise.

[0049] Moving average filtering: Take 5 to 10 consecutive sampling points and perform an arithmetic average. The window length is dynamically adjusted according to the acquisition frequency (10 points for 10Hz acquisition, 8 points for 20Hz acquisition) to smooth out sudden interference data caused by load and speed fluctuations, and avoid interference data affecting the temperature inversion correction effect.

[0050] The temperature inversion model module is communicatively connected to the temperature acquisition module and the operating condition parameter acquisition module. It is used to calculate the inversion temperature at a target location inside the traction motor bearing based on temperature data and operating condition parameters. The temperature inversion model is established based on the mapping relationship between external temperature and bearing internal temperature, which is obtained through numerical simulation. Using Abaqus simulation software, a three-dimensional heat transfer model of the traction motor and bearing is constructed. Parameters such as bearing frictional power consumption and ambient temperature are input, the convective heat transfer coefficient is set, the temperature distribution curve under given operating conditions is obtained, and a dataset of the temperature mapping relationship between external measuring points and the internal target location is output. The simulation model parameters are corrected using line experimental data to ensure that the mapping relationship error is ≤3℃.

[0051] The temperature inversion model module includes a consistency verification unit, which verifies the temperature data from multiple external temperature measurement points and removes outliers. The consistency verification unit determines outliers based on the 3σ criterion and the temperature difference between adjacent measurement points. The specific steps are as follows:

[0052] Step 1: Obtain temperature data T1, T2, ..., T at each measuring point at the same time. n (n=3~6, which is the number of measurement points);

[0053] Step 2: Calculate the mean temperature at each measuring point, μ = ΣT i / n (i=1~n), standard deviation σ=√[Σ(T i -μ)² / (n-1)];

[0054] Step 3: 3σ criterion verification: If the temperature T at a certain measuring point... i Satisfy | T i If -μ|>3σ, then mark it as a suspected outlier;

[0055] Step 4: Verification of temperature difference between adjacent measuring points: Calculate the temperature difference ΔT1 between the suspected anomaly point and two adjacent measuring points = |T i -T i-1 |、ΔT2=|T i -T i+1 (The difference between the first and last measurement points is taken when they are adjacent). If ΔT1 > 5℃ and ΔT2 > 5℃ (the threshold is based on experimental calibration), then it is judged as an outlier and removed.

[0056] Step 5: If the number of valid measuring points after removal is ≤2, then start the backup measuring point data (if available), or use historical data from the same period to interpolate and supplement the data to ensure data validity.

[0057] Furthermore, the temperature inversion model module also includes a weighted fusion unit, used to perform a weighted average of temperature data from multiple external temperature measurement points verified by the consistency check unit, to obtain the equivalent external temperature. In the weighted fusion unit, the weight of each measurement point's temperature is determined based on the heat transfer path characteristics of the measurement point, the installation distance, and experimental calibration results. The equivalent external temperature is obtained through weighted averaging.

[0058]

[0059] Weight The value is determined by the heat transfer path contribution, installation distance, and calibration results, and is in the form of... ;

[0060] in: for t The equivalent temperature at any given moment. for t Time of the first i Temperature values ​​at each measuring point The total number of samples, d i For the first i The equivalent heat transfer path distance from the measuring point to the target area of ​​the bearing. p The distance decay exponent; These are calibration coefficients; Let ∑ be a normalization constant. ω i =1.

[0061] Under controllable operating conditions, a reliable internal reference temperature curve is obtained on the disassembly platform via infrared / indirect temperature measurement, and this curve is used as the "reference value". Based on the correspondence between the internal reference temperature and external measuring points, the least squares method is employed for optimization. This minimizes the error in predicting the internal temperature.

[0062] The temperature inversion model module is also configured to adaptively correct the inverted temperature based on the deviation between the predicted and actual measured values ​​at external temperature measurement points.

[0063] The results output module is communicatively connected to the temperature inversion model module and is used to output the inverted temperature. The results output module can output the inverted temperature in various forms, such as digital values, curves, and alarm signals, through a display screen, data bus, or wireless communication interface, for use by the monitoring system or maintenance personnel.

[0064] Please refer to Figure 1 As shown, embodiments of the present invention also provide a method for inverting the internal temperature of a traction motor bearing based on an external temperature measurement point. This method includes the following steps:

[0065] S1. Acquire temperature data from various external temperature measurement points at the same time, perform consistency verification and weighted fusion on the acquired temperature data, and obtain the equivalent external temperature;

[0066] S2. Collect the operating parameters of the traction motor;

[0067] S3. Based on the equivalent external temperature collected in step S1 and the operating condition parameters collected in step S2, the inversion temperature of the target position inside the bearing of the traction motor is calculated using the temperature inversion model.

[0068] S4. Adaptively correct the inverted temperature based on the deviation between the predicted value and the actual measured value of the external temperature measuring point;

[0069] S5. Output inversion temperature.

[0070] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A traction motor bearing internal temperature inversion system based on external temperature measurement points, characterized in that, include: The temperature acquisition module is used to collect temperature data from multiple external temperature measuring points set on the outer surface of the traction motor. The operating condition parameter acquisition module is used to collect the operating condition parameters of the traction motor. The temperature inversion model module is connected to the temperature acquisition module and the operating condition parameter acquisition module. It is used to calculate the inversion temperature of the target position inside the bearing of the traction motor based on temperature data and operating condition parameters. The results output module is connected to the temperature inversion model module and is used to output the inversion temperature. The temperature inversion model module includes a consistency verification unit, which is used to verify the temperature data of multiple external temperature measurement points and remove abnormal data. The consistency verification unit determines abnormal data based on the 3σ criterion and the temperature difference verification between adjacent measurement points. The temperature inversion model module also includes a weighted fusion unit, which is used to perform a weighted average of the temperature data of multiple external temperature measurement points that have passed the consistency verification unit to obtain the equivalent external temperature. In the weighted fusion unit, the weight of each measuring point temperature is determined based on the heat transfer path characteristics of the measuring point, the installation distance, and the experimental calibration results. The equivalent external temperature is obtained by weighted averaging. Weight The value is determined by the heat transfer path contribution, installation distance, and calibration results, and is in the form of... ; in: for t The equivalent temperature at any given moment. for t Time of the first i Temperature values ​​at each measuring point The total number of samples, d i For the first i The equivalent heat transfer path distance from the measuring point to the target area of ​​the bearing. p The distance decay exponent; These are calibration coefficients; Let ∑ be a normalization constant. ω i =1; The temperature inversion model module is also configured to adaptively correct the inverted temperature based on the deviation between the predicted and actual measured values ​​at external temperature measurement points.

2. The traction motor bearing internal temperature inversion system based on external temperature measurement points according to claim 1, characterized in that, Multiple external temperature measuring points are evenly distributed along the circumference of the bearing housing.

3. The traction motor bearing internal temperature inversion system based on external temperature measurement points according to claim 1, characterized in that, The temperature acquisition module includes an external temperature sensor, which is a platinum resistance thermometer.

4. The traction motor bearing internal temperature inversion system based on external temperature measurement points according to claim 1, characterized in that, The temperature acquisition module also includes an installation structure, which includes a press-fit component and a seal. The press-fit component is used to press and fix the temperature acquisition module into the temperature measuring hole of the traction motor, and the seal is placed between the temperature acquisition module and the inner wall of the temperature measuring hole.

5. The traction motor bearing internal temperature inversion system based on external temperature measurement points according to claim 1, characterized in that, The operating condition parameter acquisition module is used to collect at least one of the following: traction motor speed, bearing load, and ambient temperature.

6. The traction motor bearing internal temperature inversion system based on external temperature measurement points according to claim 5, characterized in that, The operating condition parameter acquisition module also includes a data preprocessing unit, which is used to filter the acquired operating condition parameters. The filtering process includes Kalman filtering and moving average filtering.

7. A method for inverting the internal temperature of a traction motor bearing based on an external temperature measurement point, characterized in that, Includes the following steps: S1. Acquire temperature data from various external temperature measurement points at the same time, perform consistency verification and weighted fusion on the acquired temperature data, and obtain the equivalent external temperature; S2. Collect the operating parameters of the traction motor; S3. Based on the equivalent external temperature collected in step S1 and the operating condition parameters collected in step S2, the inversion temperature of the target position inside the bearing of the traction motor is calculated using the temperature inversion model. S4. Adaptively correct the inverted temperature based on the deviation between the predicted value and the actual measured value of the external temperature measuring point; S5. Output inversion temperature.

8. The method for inverting the internal temperature of a traction motor bearing based on an external temperature measurement point according to claim 7, characterized in that, In step S1, the weighted fusion calculation determines the weights based on the heat transfer path characteristics of the measuring points, the installation distance, and the experimental calibration results, and obtains the equivalent external temperature through weighted averaging: Weight The value is determined by the heat transfer path contribution, installation distance, and calibration results, and is in the form of... ; in: for t The equivalent temperature at any given moment. for t Time of the first i Temperature values ​​at each measuring point The total number of samples, d i For the first i The equivalent heat transfer path distance from the measuring point to the target area of ​​the bearing. p The distance decay exponent; These are calibration coefficients; This is the normalization constant.

Images